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978,497 commits
| Author | SHA1 | Message | Date | |
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Axel Rasmussen
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f852d39c08 |
FROMGIT: userfaultfd/selftests: create alias mappings in the shmem test
Previously, we just allocated two shm areas: area_src and area_dst. With this commit, change this so we also allocate area_src_alias, and area_dst_alias. area_*_alias and area_* (respectively) point to the same underlying physical pages, but are different VMAs. In a future commit in this series, we'll leverage this setup to exercise minor fault handling support for shmem, just like we do in the hugetlb_shared test. Link: https://lkml.kernel.org/r/20210503180737.2487560-9-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 9c9db903230e25c3b5547a719a883f9ba2970502 https: //git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420975/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: Ic603af85181acc60ecf4c8767c86bf8e2bb5c72c |
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Axel Rasmussen
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3aaf80e85f |
FROMGIT: userfaultfd/selftests: use memfd_create for shmem test type
This is a preparatory commit. In the future, we want to be able to setup alias mappings for area_src and area_dst in the shmem test, like we do in the hugetlb_shared test. With a VMA obtained via mmap(MAP_ANONYMOUS | MAP_SHARED), it isn't clear how to do this. So, mmap() with an fd, so we can create alias mappings. Use memfd_create instead of actually passing in a tmpfs path like hugetlb does, since it's more convenient / simpler to run, and works just as well. Future commits will: 1. Setup the alias mappings. 2. Extend our tests to actually take advantage of this, to test new userfaultfd behavior being introduced in this series. Also, a small fix in the area we're changing: when the hugetlb setup fails in main(), pass in the right argv[] so we actually print out the hugetlb file path. Link: https://lkml.kernel.org/r/20210503180737.2487560-8-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 1861e1c4ef590b7f3f8318da5f681efeb2686449 https: //git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420976/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: Id8fc463cef73e8e99190f0d748e4d92ada8541a4 |
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Axel Rasmussen
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f98960cd4b |
BACKPORT: FROMGIT: userfaultfd/shmem: modify shmem_mfill_atomic_pte to use install_pte()
In a previous commit, we added the mfill_atomic_install_pte() helper. This helper does the job of setting up PTEs for an existing page, to map it into a given VMA. It deals with both the anon and shmem cases, as well as the shared and private cases. In other words, shmem_mfill_atomic_pte() duplicates a case it already handles. So, expose it, and let shmem_mfill_atomic_pte() use it directly, to reduce code duplication. This requires that we refactor shmem_mfill_atomic_pte() a bit: Instead of doing accounting (shmem_recalc_inode() et al) part-way through the PTE setup, do it afterward. This frees up mfill_atomic_install_pte() from having to care about this accounting, and means we don't need to e.g. shmem_uncharge() in the error path. A side effect is this switches shmem_mfill_atomic_pte() to use lru_cache_add_inactive_or_unevictable() instead of just lru_cache_add(). This wrapper does some extra accounting in an exceptional case, if appropriate, so it's actually the more correct thing to use. Link: https://lkml.kernel.org/r/20210503180737.2487560-7-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 42660ee254d889478c4d12929875f4d0ab067ca4 https: //git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420973/ Conflicts: 1. mm/shmem.c 2. mm/userfaultfd.c (1. Incorporated mem_cgroup_try_charge() into the patch 2. Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I130c9f7cdfe0404dbd7bed48f19eddec65ea1c48 |
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Axel Rasmussen
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5679fd2c2b |
BACKPORT: FROMGIT: userfaultfd/shmem: advertise shmem minor fault support
Now that the feature is fully implemented (the faulting path hooks exist so userspace is notified, and the ioctl to resolve such faults is available), advertise this as a supported feature. Link: https://lkml.kernel.org/r/20210503180737.2487560-6-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 37aa962fe33a562fd0ac21b68938023e12041fc3 https: //git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420971/ Conflicts: Documentation/admin-guide/mm/userfaultfd.rst (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I5fbab3783ff8671c0a5aa4826aead2d63f5cbbf3 |
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Axel Rasmussen
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ef31d0b42c |
BACKPORT: FROMGIT: userfaultfd/shmem: support UFFDIO_CONTINUE for shmem
With this change, userspace can resolve a minor fault within a shmem-backed area with a UFFDIO_CONTINUE ioctl. The semantics for this match those for hugetlbfs - we look up the existing page in the page cache, and install a PTE for it. This commit introduces a new helper: mfill_atomic_install_pte. Why handle UFFDIO_CONTINUE for shmem in mm/userfaultfd.c, instead of in shmem.c? The existing userfault implementation only relies on shmem.c for VM_SHARED VMAs. However, minor fault handling / CONTINUE work just fine for !VM_SHARED VMAs as well. We'd prefer to handle CONTINUE for shmem in one place, regardless of shared/private (to reduce code duplication). Why add a new mfill_atomic_install_pte helper? A problem we have with continue is that shmem_mfill_atomic_pte() and mcopy_atomic_pte() are *close* to what we want, but not exactly. We do want to setup the PTEs in a CONTINUE operation, but we don't want to e.g. allocate a new page, charge it (e.g. to the shmem inode), manipulate various flags, etc. Also we have the problem stated above: shmem_mfill_atomic_pte() and mcopy_atomic_pte() both handle one-half of the problem (shared / private) continue cares about. So, introduce mcontinue_atomic_pte(), to handle all of the shmem continue cases. Introduce the helper so it doesn't duplicate code with mcopy_atomic_pte(). In a future commit, shmem_mfill_atomic_pte() will also be modified to use this new helper. However, since this is a bigger refactor, it seems most clear to do it as a separate change. Link: https://lkml.kernel.org/r/20210503180737.2487560-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit c9a4579a9f5320ff062f973476473242b551bacd https: //git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420972/ Conflicts: mm/userfaultfd.c (1. Removed all 'wp_copy' usage as write-protect uffd feature doesn't exist in this kernel. 2. Due to lack of mem_cgroup_charge() in this kernel, worked with mem_cgroup_try_charge() instead in mcopy_atomic_pte() 3. Replaced lru_cache_add_inactive_or_unevictable() with lru_cache_add_active_or_unevictable()) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I46eb835849e7798a9d23cf53959bd93655b926d4 |
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Axel Rasmussen
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ec166f77f9 |
BACKPORT: FROMGIT: userfaultfd/shmem: support minor fault registration for shmem
This patch allows shmem-backed VMAs to be registered for minor faults. Minor faults are appropriately relayed to userspace in the fault path, for VMAs with the relevant flag. This commit doesn't hook up the UFFDIO_CONTINUE ioctl for shmem-backed minor faults, though, so userspace doesn't yet have a way to resolve such faults. Because of this, we also don't yet advertise this as a supported feature. That will be done in a separate commit when the feature is fully implemented. Link: https://lkml.kernel.org/r/20210503180737.2487560-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Acked-by: Peter Xu <peterx@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 6867a29320b7d178feb9786856e5ea2cf40f6d33 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420970/ Conflicts: mm/shmem.c (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: Ib8e3fe202feab7404742814f4250a0981065368c |
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Axel Rasmussen
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c374e699af |
BACKPORT: FROMGIT: userfaultfd/shmem: combine shmem_{mcopy_atomic,mfill_zeropage}_pte
Patch series "userfaultfd: add minor fault handling for shmem", v6. Overview ======== See the series which added minor faults for hugetlbfs [3] for a detailed overview of minor fault handling in general. This series adds the same support for shmem-backed areas. This series is structured as follows: - Commits 1 and 2 are cleanups. - Commits 3 and 4 implement the new feature (minor fault handling for shmem). - Commit 5 advertises that the feature is now available since at this point it's fully implemented. - Commit 6 is a final cleanup, modifying an existing code path to re-use a new helper we've introduced. - Commits 7, 8, 9, 10 update the userfaultfd selftest to exercise the feature. Use Case ======== In some cases it is useful to have VM memory backed by tmpfs instead of hugetlbfs. So, this feature will be used to support the same VM live migration use case described in my original series. Additionally, Android folks (Lokesh Gidra <lokeshgidra@google.com>) hope to optimize the Android Runtime garbage collector using this feature: "The plan is to use userfaultfd for concurrently compacting the heap. With this feature, the heap can be shared-mapped at another location where the GC-thread(s) could continue the compaction operation without the need to invoke userfault ioctl(UFFDIO_COPY) each time. OTOH, if and when Java threads get faults on the heap, UFFDIO_CONTINUE can be used to resume execution. Furthermore, this feature enables updating references in the 'non-moving' portion of the heap efficiently. Without this feature, uneccessary page copying (ioctl(UFFDIO_COPY)) would be required." [1] https://lore.kernel.org/patchwork/cover/1388144/ [2] https://lore.kernel.org/patchwork/patch/1408161/ [3] https://lore.kernel.org/linux-fsdevel/20210301222728.176417-1-axelrasmussen@google.com/T/#t This patch (of 9): Previously, we did a dance where we had one calling path in userfaultfd.c (mfill_atomic_pte), but then we split it into two in shmem_fs.h (shmem_{mcopy_atomic,mfill_zeropage}_pte), and then rejoined into a single shared function in shmem.c (shmem_mfill_atomic_pte). This is all a bit overly complex. Just call the single combined shmem function directly, allowing us to clean up various branches, boilerplate, etc. While we're touching this function, two other small cleanup changes: - offset is equivalent to pgoff, so we can get rid of offset entirely. - Split two VM_BUG_ON cases into two statements. This means the line number reported when the BUG is hit specifies exactly which condition was true. Link: https://lkml.kernel.org/r/20210503180737.2487560-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210503180737.2487560-3-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit f7e89f242f0dfcdd62e7aeecebdc2620e4792954 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420969/ Conflicts: 1. include/linux/shmem_fs.h 2. mm/shmem.c 3. mm/userfaultfd.c (All resolved by manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I8b443809643339b407d0bc06bf96146ecfc5a9fa |
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Peter Xu
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af9759f100 |
BACKPORT: FROMGIT: userfaultfd/selftests: unify error handling
Introduce err()/_err() and replace all the different ways to fail the program, mostly "fprintf" and "perror" with tons of exit() calls. Always stop the test program at any failure. Link: https://lkml.kernel.org/r/20210412232753.1012412-6-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit fcd7d008016c9bc9bf134debfd077d59bba119d8 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1412454/ Conflicts: tools/testing/selftests/vm/userfaultfd.c (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: Ic39dd286c3b1938752c3dc8c060a15b3d5db6564 |
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Peter Xu
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87f0b565c1 |
BACKPORT: FROMGIT: userfaultfd/selftests: only dump counts if mode enabled
WP and MINOR modes are conditionally enabled on specific memory types. This patch avoids dumping tons of zeros for those cases when the modes are not supported at all. Link: https://lkml.kernel.org/r/20210412232753.1012412-5-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 5edabbbe74eee6c1c59dafbbfb5528e391be447c https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1412453/ Conflicts: tools/testing/selftests/vm/userfaultfd.c (1. Manual rebase 2. Removed 'wp_total' related change in uffd_stats_report() as write-protect test doesn't exist.) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I445f883f3402104ea39d50ea60726b16394f6e50 |
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Axel Rasmussen
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ce0a7ce64d |
BACKPORT: userfaultfd/selftests: add test exercising minor fault handling
Fix a dormant bug in userfaultfd_events_test(), where we did `return faulting_process(0)` instead of `exit(faulting_process(0))`. This caused the forked process to keep running, trying to execute any further test cases after the events test in parallel with the "real" process. Add a simple test case which exercises minor faults. In short, it does the following: 1. "Sets up" an area (area_dst) and a second shared mapping to the same underlying pages (area_dst_alias). 2. Register one of these areas with userfaultfd, in minor fault mode. 3. Start a second thread to handle any minor faults. 4. Populate the underlying pages with the non-UFFD-registered side of the mapping. Basically, memset() each page with some arbitrary contents. 5. Then, using the UFFD-registered mapping, read all of the page contents, asserting that the contents match expectations (we expect the minor fault handling thread can modify the page contents before resolving the fault). The minor fault handling thread, upon receiving an event, flips all the bits (~) in that page, just to prove that it can modify it in some arbitrary way. Then it issues a UFFDIO_CONTINUE ioctl, to setup the mapping and resolve the fault. The reading thread should wake up and see this modification. Currently the minor fault test is only enabled in hugetlb_shared mode, as this is the only configuration the kernel feature supports. Link: https://lkml.kernel.org/r/20210301222728.176417-7-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit f0fa94330919be8ec5620382b50f1c72844c9224) Conflicts: tools/testing/selftests/vm/userfaultfd.c (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I85a490f0c4d0a1f462ae01231c3853d6ffc23d2b |
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Lokesh Gidra
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238aff8de5 |
BACKPORT: userfaultfd: selftests: add write-protect test
Add uffd tests for write protection.
Instead of introducing new tests for it, let's simply squashing uffd-wp
tests into existing uffd-missing test cases. Changes are:
(1) Bouncing tests
We do the write-protection in two ways during the bouncing test:
- By using UFFDIO_COPY_MODE_WP when resolving MISSING pages: then
we'll make sure for each bounce process every single page will be
at least fault twice: once for MISSING, once for WP.
- By direct call UFFDIO_WRITEPROTECT on existing faulted memories:
To further torture the explicit page protection procedures of
uffd-wp, we split each bounce procedure into two halves (in the
background thread): the first half will be MISSING+WP for each
page as explained above. After the first half, we write protect
the faulted region in the background thread to make sure at least
half of the pages will be write protected again which is the first
half to test the new UFFDIO_WRITEPROTECT call. Then we continue
with the 2nd half, which will contain both MISSING and WP faulting
tests for the 2nd half and WP-only faults from the 1st half.
(2) Event/Signal test
Mostly previous tests but will do MISSING+WP for each page. For
sigbus-mode test we'll need to provide standalone path to handle the
write protection faults.
For all tests, do statistics as well for uffd-wp pages.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-20-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 9b12488a7711b9aa2d0915f6949a8ad2069eb072)
Conflicts: tools/testing/selftests/vm/userfaultfd.c
(Removed write-protect test related changes)
Note: This patch introduces a write-protect test. In addition it also
introduces uffd_stats_report(), which prints the stats in uniform a
manner. We only require uffd_stats_report() as subsequent patches depend
on it. Write-protect test is omitted as this kernel doesn't have
userfaultfd's write-protect feature.
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Bug: 187930641
Change-Id: Iad7012e086016e4a67a283c4997d8f7be92eea74
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Peter Xu
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b148186e40 |
BACKPORT: userfaultfd: selftests: refactor statistics
Introduce uffd_stats structure for statistics of the self test, at the same time refactor the code to always pass in the uffd_stats for either read() or poll() typed fault handling threads instead of using two different ways to return the statistic results. No functional change. With the new structure, it's very easy to introduce new statistics. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Brian Geffon <bgeffon@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@fb.com> Link: http://lkml.kernel.org/r/20200220163112.11409-19-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit 5c8aed6c1b95c3c6de68bd2814611d5d54da5057) Conflicts: tools/testing/selftests/vm/userfaultfd.c (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I93597413653e9d55954e7912db56794e4ae446be |
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Lokesh Gidra
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9ade127571 |
Revert "BACKPORT: FROMGIT: userfaultfd/selftests: add test exercising minor fault handling"
This reverts commit 2b2f7d6a04d65c2ebd53f9e5d3de6b55635d57b6 so that it can be re-applied once dependcies are brought in. Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: Ib24c94e1d8ec6c46004d35f58e48d9d35eeb8312 |
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Lokesh Gidra
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20c5c31e6e |
Revert "BACKPORT: FROMGIT: userfaultfd: support minor fault handling for shmem"
This reverts commit 0309b3f479b967acb644f99d214e2b25297a20b1 as an updated version of the patch-set will be merged later. Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I765fe86a2dc0305482a0590c14143dee27840b8a |
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Lokesh Gidra
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59a9ac69f8 |
Revert "FROMGIT: userfaultfd/selftests: use memfd_create for shmem test type"
This reverts commit f8bed3c813cb21c9c576d42068994e0199773f96 as an updated version of the patch-set will be merged later. Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I808f6c58429c83f03eae2ad2cbe65a232b2505c8 |
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Lokesh Gidra
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5d844e34c5 |
Revert "FROMGIT: userfaultfd/selftests: create alias mappings in the shmem test"
This reverts commit 08dec4889aede52e2f09ae2333c8a292aa12d359 as an updated version of the patch-set will be merged later. Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I13e7cac79661ef46882cc69ab60327fafd212093 |
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Lokesh Gidra
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56ccf7d575 |
Revert "BACKPORT: FROMGIT: userfaultfd/selftests: reinitialize test context in each test"
This reverts commit 2ed6377e515707a52d123b735d861a7b8305eceb as an updated version of the patch-set will be merged later. Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: I239e3f80e27d7e86dc9911cc3dd5640fc2d9bf94 |
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Lokesh Gidra
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542ffaa634 |
Revert "BACKPORT: FROMGIT: userfaultfd/selftests: exercise minor fault handling shmem support"
This reverts commit 44f2dcd54e168d03c32ef4730596783bff3180f7. as an updated version of the patch-set will be merged later. Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug 187930641 Change-Id: Iec5f001d559609b4b3a2239a2b92cd46778437ca |
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Lokesh Gidra
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41c5a99009 |
Revert "FROMLIST: userfaultfd/shmem: fix minor fault page leak"
This reverts commit 33a50fd21ddb04629ba4a262f3cdcdc2f43ee578 as an updated version of the patch-set will be merged later. Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 187930641 Change-Id: Ie6fe2a611d4cbb3bd103c62a90b84e6ba4e89af1 |
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Shaohua Li
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d28487ec26 |
BACKPORT: userfaultfd: wp: add helper for writeprotect check
Patch series "userfaultfd: write protection support", v6.
Overview
========
The uffd-wp work was initialized by Shaohua Li [1], and later continued by
Andrea [2]. This series is based upon Andrea's latest userfaultfd tree,
and it is a continuous works from both Shaohua and Andrea. Many of the
follow up ideas come from Andrea too.
Besides the old MISSING register mode of userfaultfd, the new uffd-wp
support provides another alternative register mode called
UFFDIO_REGISTER_MODE_WP that can be used to listen to not only missing
page faults but also write protection page faults, or even they can be
registered together. At the same time, the new feature also provides a
new userfaultfd ioctl called UFFDIO_WRITEPROTECT which allows the
userspace to write protect a range or memory or fixup write permission of
faulted pages.
Please refer to the document patch "userfaultfd: wp:
UFFDIO_REGISTER_MODE_WP documentation update" for more information on the
new interface and what it can do.
The major workflow of an uffd-wp program should be:
1. Register a memory region with WP mode using UFFDIO_REGISTER_MODE_WP
2. Write protect part of the whole registered region using
UFFDIO_WRITEPROTECT, passing in UFFDIO_WRITEPROTECT_MODE_WP to
show that we want to write protect the range.
3. Start a working thread that modifies the protected pages,
meanwhile listening to UFFD messages.
4. When a write is detected upon the protected range, page fault
happens, a UFFD message will be generated and reported to the
page fault handling thread
5. The page fault handler thread resolves the page fault using the
new UFFDIO_WRITEPROTECT ioctl, but this time passing in
!UFFDIO_WRITEPROTECT_MODE_WP instead showing that we want to
recover the write permission. Before this operation, the fault
handler thread can do anything it wants, e.g., dumps the page to
a persistent storage.
6. The worker thread will continue running with the correctly
applied write permission from step 5.
Currently there are already two projects that are based on this new
userfaultfd feature.
QEMU Live Snapshot: The project provides a way to allow the QEMU
hypervisor to take snapshot of VMs without
stopping the VM [3].
LLNL umap library: The project provides a mmap-like interface and
"allow to have an application specific buffer of
pages cached from a large file, i.e. out-of-core
execution using memory map" [4][5].
Before posting the patchset, this series was smoke tested against QEMU
live snapshot and the LLNL umap library (by doing parallel quicksort using
128 sorting threads + 80 uffd servicing threads). My sincere thanks to
Marty Mcfadden and Denis Plotnikov for the help along the way.
TODO
====
- hugetlbfs/shmem support
- performance
- more architectures
- cooperate with mprotect()-allowed processes (???)
- ...
References
==========
[1] https://lwn.net/Articles/666187/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git/log/?h=userfault
[3] https://github.com/denis-plotnikov/qemu/commits/background-snapshot-kvm
[4] https://github.com/LLNL/umap
[5] https://llnl-umap.readthedocs.io/en/develop/
[6] https://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git/commit/?h=userfault&id=b245ecf6cf59156966f3da6e6b674f6695a5ffa5
[7] https://lkml.org/lkml/2018/11/21/370
[8] https://lkml.org/lkml/2018/12/30/64
This patch (of 19):
Add helper for writeprotect check. Will use it later.
Bug: 254441685
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Link: http://lkml.kernel.org/r/20200220163112.11409-2-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 1df319e0b4dee11436fe2ab1a0d536d3fad7cfef)
[Lee: Dependency for Fixes: commit 6ce64428d6202 ("mm/userfaultfd: fix memory corruption due to writeprotect"))
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I0c09235bb2e3ac9abd7aa5d5ba1cdba19d2afbb7
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Dmitry Safonov
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50873dd8ff |
UPSTREAM: mm/mremap: don't account pages in vma_to_resize()
All this vm_unacct_memory(charged) dance seems to complicate the life without a good reason. Furthermore, it seems not always done right on error-pathes in mremap_to(). And worse than that: this `charged' difference is sometimes double-accounted for growing MREMAP_DONTUNMAP mremap()s in move_vma(): if (security_vm_enough_memory_mm(mm, new_len >> PAGE_SHIFT)) Let's not do this. Account memory in mremap() fast-path for growing VMAs or in move_vma() for actually moving things. The same simpler way as it's done by vm_stat_account(), but with a difference to call security_vm_enough_memory_mm() before copying/adjusting VMA. Originally noticed by Chen Wandun: https://lkml.kernel.org/r/20210717101942.120607-1-chenwandun@huawei.com Link: https://lkml.kernel.org/r/20210721131320.522061-1-dima@arista.com Fixes: e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()") Signed-off-by: Dmitry Safonov <dima@arista.com> Acked-by: Brian Geffon <bgeffon@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen Wandun <chenwandun@huawei.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yongjun <weiyongjun1@huawei.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit fdbef61491359947753c13581098878e8d038286) Signed-off-by: Lee Jones <lee.jones@linaro.org> Change-Id: Id0833f3e84c4a6119e2ec069afff5122cb0c6b35 |
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Brian Geffon
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2af548dd44 |
BACKPORT: FROMLIST: Revert "mremap: don't allow MREMAP_DONTUNMAP on special_mappings and aio"
This reverts commit cd544fd1dc9293c6702fab6effa63dac1cc67e99. As discussed in [1] this commit was a no-op because the mapping type was checked in vma_to_resize before move_vma is ever called. This meant that vm_ops->mremap() would never be called on such mappings. Furthermore, we've since expanded support of MREMAP_DONTUNMAP to non-anonymous mappings, and these special mappings are still protected by the existing check of !VM_DONTEXPAND and !VM_PFNMAP which will result in a -EINVAL. 1. https://lkml.org/lkml/2020/12/28/2340 Signed-off-by: Brian Geffon <bgeffon@google.com> Acked-by: Hugh Dickins <hughd@google.com> Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Link: https://lore.kernel.org/patchwork/patch/1401226/ Conflicts: include/linux/mm.h (Resolved minor conflict with manual rebase) Bug: 160737021 Bug: 169683130 Change-Id: I97d29e6a54cee07ba69d6bb880778ee1fea8ff7c |
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Brian Geffon
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7629defaa9 |
FROMLIST: mm: Extend MREMAP_DONTUNMAP to non-anonymous mappings
Currently MREMAP_DONTUNMAP only accepts private anonymous mappings. This restriction was placed initially for simplicity and not because there exists a technical reason to do so. This change will widen the support to include any mappings which are not VM_DONTEXPAND or VM_PFNMAP. The primary use case is to support MREMAP_DONTUNMAP on mappings which may have been created from a memfd. This change will result in mremap(MREMAP_DONTUNMAP) returning -EINVAL if VM_DONTEXPAND or VM_PFNMAP mappings are specified. Lokesh Gidra who works on the Android JVM, provided an explanation of how such a feature will improve Android JVM garbage collection: "Android is developing a new garbage collector (GC), based on userfaultfd. The garbage collector will use userfaultfd (uffd) on the java heap during compaction. On accessing any uncompacted page, the application threads will find it missing, at which point the thread will create the compacted page and then use UFFDIO_COPY ioctl to get it mapped and then resume execution. Before starting this compaction, in a stop-the-world pause the heap will be mremap(MREMAP_DONTUNMAP) so that the java heap is ready to receive UFFD_EVENT_PAGEFAULT events after resuming execution. To speedup mremap operations, pagetable movement was optimized by moving PUD entries instead of PTE entries [1]. It was necessary as mremap of even modest sized memory ranges also took several milliseconds, and stopping the application for that long isn't acceptable in response-time sensitive cases. With UFFDIO_CONTINUE feature [2], it will be even more efficient to implement this GC, particularly the 'non-moveable' portions of the heap. It will also help in reducing the need to copy (UFFDIO_COPY) the pages. However, for this to work, the java heap has to be on a 'shared' vma. Currently MREMAP_DONTUNMAP only supports private anonymous mappings, this patch will enable using UFFDIO_CONTINUE for the new userfaultfd-based heap compaction." [1] https://lore.kernel.org/linux-mm/20201215030730.NC3CU98e4%25akpm@linux-foundation.org/ [2] https://lore.kernel.org/linux-mm/20210302000133.272579-1-axelrasmussen@google.com/ Signed-off-by: Brian Geffon <bgeffon@google.com> Acked-by: Hugh Dickins <hughd@google.com> Tested-by: Lokesh Gidra <lokeshgidra@google.com> Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Link: https://lore.kernel.org/patchwork/patch/1401224/ Bug: 160737021 Bug: 169683130 Change-Id: Ic4f023dff404d7b0e35adbe92c7a12536aa0f70d |
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Dmitry Safonov
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13575f869d |
UPSTREAM: mremap: don't allow MREMAP_DONTUNMAP on special_mappings and aio
As kernel expect to see only one of such mappings, any further operations on the VMA-copy may be unexpected by the kernel. Maybe it's being on the safe side, but there doesn't seem to be any expected use-case for this, so restrict it now. Link: https://lkml.kernel.org/r/20201013013416.390574-4-dima@arista.com Fixes: commit e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()") Signed-off-by: Dmitry Safonov <dima@arista.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit cd544fd1dc9293c6702fab6effa63dac1cc67e99) Bug: 176847609 Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Change-Id: I9fc569e41bd7fc07c2a168c96d83eda0396c2305 |
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Dmitry Safonov
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958bc1f599 |
BACKPORT: mm/mremap: for MREMAP_DONTUNMAP check security_vm_enough_memory_mm()
Currently memory is accounted post-mremap() with MREMAP_DONTUNMAP, which may break overcommit policy. So, check if there's enough memory before doing actual VMA copy. Don't unset VM_ACCOUNT on MREMAP_DONTUNMAP. By semantics, such mremap() is actually a memory allocation. That also simplifies the error-path a little. Also, as it's memory allocation on success don't reset hiwater_vm value. Link: https://lkml.kernel.org/r/20201013013416.390574-3-dima@arista.com Fixes: commit e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()") Signed-off-by: Dmitry Safonov <dima@arista.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit ad8ee77ea9db1f74fe79c285e3546375efa75608) [Kalesh Singh: Resolve conflicts in mm/mremap.c] Bug: 176847609 Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Change-Id: If8e8bf5a18d16ed6b40af22a685951698e6f444c |
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Arnaldo Carvalho de Melo
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9274b888a1 |
UPSTREAM: tools headers UAPI: Sync linux/mman.h with the kernel
To get the changes in:
e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Add that to 'perf trace's mremap 'flags' decoder.
This silences this perf build warning:
Warning: Kernel ABI header at 'tools/include/uapi/linux/mman.h' differs from latest version at 'include/uapi/linux/mman.h'
diff -u tools/include/uapi/linux/mman.h include/uapi/linux/mman.h
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
(cherry picked from commit f60b3878f47311a61fe2d4c5ef77c52e31554c52)
Bug: 176847609
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Change-Id: Iab7117411cf9c4c32356da2b3de598a0df299a7c
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Brian Geffon
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33293c4df9 |
UPSTREAM: userfaultfd: fix remap event with MREMAP_DONTUNMAP
A user is not required to set a new address when using MREMAP_DONTUNMAP
as it can be used without MREMAP_FIXED. When doing so the remap event
will use new_addr which may not have been set and we didn't propagate it
back other then in the return value of remap_to.
Because ret is always the new address it's probably more correct to use
it rather than new_addr on the remap_event_complete call, and it
resolves this bug.
Fixes: e346b3813067d4b ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Michael S . Tsirkin" <mst@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Sonny Rao <sonnyrao@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Link: http://lkml.kernel.org/r/20200506172158.218366-1-bgeffon@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit d1564926066115fb47ca06b2b9d23ed506ca9608)
Bug: 176847609
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Change-Id: I7a20139ee14a2c9124b74310d7c0324c11009087
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Brian Geffon
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f1934d352a |
UPSTREAM: mm: Fix MREMAP_DONTUNMAP accounting on VMA merge
When remapping a mapping where a portion of a VMA is remapped into another portion of the VMA it can cause the VMA to become split. During the copy_vma operation the VMA can actually be remerged if it's an anonymous VMA whose pages have not yet been faulted. This isn't normally a problem because at the end of the remap the original portion is unmapped causing it to become split again. However, MREMAP_DONTUNMAP leaves that original portion in place which means that the VMA which was split and then remerged is not actually split at the end of the mremap. This patch fixes a bug where we don't detect that the VMAs got remerged and we end up putting back VM_ACCOUNT on the next mapping which is completely unreleated. When that next mapping is unmapped it results in incorrectly unaccounting for the memory which was never accounted, and eventually we will underflow on the memory comittment. There is also another issue which is similar, we're currently accouting for the number of pages in the new_vma but that's wrong. We need to account for the length of the remap operation as that's all that is being added. If there was a mapping already at that location its comittment would have been adjusted as part of the munmap at the start of the mremap. A really simple repro can be seen in: https://gist.github.com/bgaff/e101ce99da7d9a8c60acc641d07f312c Fixes: e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Brian Geffon <bgeffon@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit dadbd85f2afc8ccd1dd1f0131781c740c91edd96) Bug: 176847609 Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Change-Id: I823b63d110825c306dab6929fca9408f8bf79ff0 |
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Brian Geffon
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a3967e5ebe |
UPSTREAM: mm/mremap: add MREMAP_DONTUNMAP to mremap()
When remapping an anonymous, private mapping, if MREMAP_DONTUNMAP is set, the source mapping will not be removed. The remap operation will be performed as it would have been normally by moving over the page tables to the new mapping. The old vma will have any locked flags cleared, have no pagetables, and any userfaultfds that were watching that range will continue watching it. For a mapping that is shared or not anonymous, MREMAP_DONTUNMAP will cause the mremap() call to fail. Because MREMAP_DONTUNMAP always results in moving a VMA you MUST use the MREMAP_MAYMOVE flag, it's not possible to resize a VMA while also moving with MREMAP_DONTUNMAP so old_len must always be equal to the new_len otherwise it will return -EINVAL. We hope to use this in Chrome OS where with userfaultfd we could write an anonymous mapping to disk without having to STOP the process or worry about VMA permission changes. This feature also has a use case in Android, Lokesh Gidra has said that "As part of using userfaultfd for GC, We'll have to move the physical pages of the java heap to a separate location. For this purpose mremap will be used. Without the MREMAP_DONTUNMAP flag, when I mremap the java heap, its virtual mapping will be removed as well. Therefore, we'll require performing mmap immediately after. This is not only time consuming but also opens a time window where a native thread may call mmap and reserve the java heap's address range for its own usage. This flag solves the problem." [bgeffon@google.com: v6] Link: http://lkml.kernel.org/r/20200218173221.237674-1-bgeffon@google.com [bgeffon@google.com: v7] Link: http://lkml.kernel.org/r/20200221174248.244748-1-bgeffon@google.com Signed-off-by: Brian Geffon <bgeffon@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Lokesh Gidra <lokeshgidra@google.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Michael S . Tsirkin" <mst@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Will Deacon <will@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Jesse Barnes <jsbarnes@google.com> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Florian Weimer <fweimer@redhat.com> Link: http://lkml.kernel.org/r/20200207201856.46070-1-bgeffon@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit e346b3813067d4b17383f975f197a9aa28a3b077) Bug: 176847609 Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Change-Id: I8474cd9f032de02fa1764c49c63d368ac15346da |
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Orson Zhai
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91e49e5534 |
ANDROID: userfaultfd: Fix untag pointer in userfaultfd_continue()
Fixes e71e2ace5721 ("userfaultfd: do not untag user pointers").
Above patch is ported from upstream into LTS branch then merged into
android12-5.4. The original patch was going to fix all untag user
pointers.
The change to userfaultfd_continue() was cut off when being merged into
LTS because the routine does not exist in LTS.
But specially the routine has been cherry-picked into android12-5.4 with
commit b69f713e60d0 ("BACKPORT: FROMGIT: userfaultfd: add
UFFDIO_CONTINUE ioctl") by Lokesh Gidra <lokeshgidra@google.com> long
ago.
So add back the missing part of fixing here.
Fixes: e71e2ace5721 ("userfaultfd: do not untag user pointers")
Change-Id: I32da80c2e9517356daadf566a433e056f6bef08c
Signed-off-by: Orson Zhai <orson.zhai@unisoc.com>
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Axel Rasmussen
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3c4f4023a8 |
FROMLIST: userfaultfd/shmem: fix minor fault page leak
This fix is analogous to Peter Xu's fix for hugetlb [0]. If we don't
put_page() after getting the page out of the page cache, we leak the
reference.
The fix can be verified by checking /proc/meminfo and running the
userfaultfd selftest in shmem mode. Without the fix, we see MemFree /
MemAvailable steadily decreasing with each run of the test. With the
fix, memory is correctly freed after the test program exits.
Fixes: 00da60b9d0a0 ("userfaultfd: support minor fault handling for shmem")
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/patchwork/patch/1400686/
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Bug: 160737021
Bug: 169683130
Change-Id: I599f1434e24fce6e31d0d73c7f9c4714e9875b63
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Peter Xu
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baf24c949a |
BACKPORT: FROMLIST: userfaultfd/hugetlbfs: Fix minor fault page leak
When uffd-minor enabled, we need to put the page cache before handling the
userfault in hugetlb_no_page(), otherwise the page refcount got leaked.
This can be reproduced by running userfaultfd selftest with hugetlb_shared
mode, then cat /proc/meminfo.
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: f2bf15fb0969 ("userfaultfd: add minor fault registration mode")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Link: https://lore.kernel.org/patchwork/patch/1400632/
Conflicts: mm/hugetlb.c
(manual rebase)
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Bug: 160737021
Bug: 169683130
Change-Id: Iac0ebd6738af8b6212c5a6303e4ee2f482bb5841
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Peter Xu
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30cd89e371 |
BACKPORT: FROMGIT: userfaultfd/selftests: drop VERIFY check in locking_thread
It tries to check against all zeros and looped for quite a few times. However after that we'll verify the same page with count_verify, while count_verify can never be zero. So it means if it's a zero page we'll detect it anyways with below code. There's yet another place we conditionally check the fault flag - just do it unconditionally. Link: https://lkml.kernel.org/r/20210310004511.51996-4-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 9c42d387952986b4159ce304a14771a0534469b3 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1392478/ Conflicts: tools/testing/selftests/vm/userfaultfd.c (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: Iee4e4fa10db0b2a01cb4804087275d2714e477b4 |
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Peter Xu
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88407480bb |
FROMGIT: userfaultfd/selftests: remove the time() check on delayed uffd
There seems to have no guarantee that time() will return the same for the two calls even if there's no delay, e.g. when a fault is accidentally crossing the changing of a second. Meanwhile, this message is also not helping that much since delay could happen with a lot of reasons, e.g., schedule latency of resolving thread. It may not mean an issue with uffd. Neither do I see this error triggered either in the past runs. Even if it triggers, it'll be drown in all the rest of test logs. Remove it. Link: https://lkml.kernel.org/r/20210310004511.51996-3-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 9c08bd6a7410e916a8d38e932d913bb240219745 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1392477/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I09b7b75425115653ee6082e7f1846984fba197fe |
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Peter Xu
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c21e5dd2d6 |
FROMGIT: userfaultfd/selftests: use user mode only
Patch series "userfaultfd/selftests: A few cleanups". I wanted to cleanup userfaultfd.c fault handling for a long time. If it's not cleaned, when the new code grows the file it'll also grow the size that needs to be cleaned... This is my attempt to cleanup the userfaultfd selftest on fault handling, to use an err() macro instead of either fprintf() or perror() then another exit() call. The huge cleanup is done in the last patch. The first 4 patches are some other standalone cleanups for the same file, so I put them together. This patch (of 5): Userfaultfd selftest does not need to handle kernel initiated fault. Set user mode so it can be run even if unprivileged_userfaultfd=0 (which is the default). Link: https://lkml.kernel.org/r/20210310004511.51996-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit eaf221e6a1916d2471309800e4534bdc0698af33 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1392475/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: Ie3f0708b3c1a25ea66e4e0795e4ea54ca938c7a1 |
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Axel Rasmussen
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3325f0ceaf |
BACKPORT: FROMGIT: userfaultfd/selftests: exercise minor fault handling shmem support
Enable test_uffdio_minor for test_type == TEST_SHMEM, and modify the test slightly to pass in / check for the right feature flags. Link: https://lkml.kernel.org/r/20210302000133.272579-6-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 01d5af3a0bc027d51d729cefe3105c7054182df7 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388148/ Conflicts: tools/testing/selftests/vm/userfaultfd.c (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I545c6b7058f59fe5bc21d2dd37202209253f1a92 |
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Axel Rasmussen
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9302deed1a |
BACKPORT: FROMGIT: userfaultfd/selftests: reinitialize test context in each test
Currently, the context (fds, mmap-ed areas, etc.) are global. Each test mutates this state in some way, in some cases really "clobbering it" (e.g., the events test mremap-ing area_dst over the top of area_src, or the minor faults tests overwriting the count_verify values in the test areas). We run the tests in a particular order, each test is careful to make the right assumptions about its starting state, etc. But, this is fragile. It's better for a test's success or failure to not depend on what some other prior test case did to the global state. To that end, clear and reinitialize the test context at the start of each test case, so whatever prior test cases did doesn't affect future tests. This is particularly relevant to this series because the events test's mremap of area_dst screws up assumptions the minor fault test was relying on. This wasn't a problem for hugetlb, as we don't mremap in that case. Link: https://lkml.kernel.org/r/20210302000133.272579-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 0108aac75e6d6852e8bba20d5b94e29bf8dc9335 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388145/ Conflicts: tools/testing/selftests/vm/userfaultfd.c (Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: Icf57513cad6f6580114bc5452bfadc5e528434ed |
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Axel Rasmussen
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7e738f2d9a |
FROMGIT: userfaultfd/selftests: create alias mappings in the shmem test
Previously, we just allocated two shm areas: area_src and area_dst. With this commit, change this so we also allocate area_src_alias, and area_dst_alias. area_*_alias and area_* (respectively) point to the same underlying physical pages, but are different VMAs. In a future commit in this series, we'll leverage this setup to exercise minor fault handling support for shmem, just like we do in the hugetlb_shared test. Link: https://lkml.kernel.org/r/20210302000133.272579-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 8bc5e62208bcb9427ea6eed94ff1b152598da6f8 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388149/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I1605dba2d5f0e35bfd57bd9110bb54e950faab19 |
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Axel Rasmussen
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195eef95ec |
FROMGIT: userfaultfd/selftests: use memfd_create for shmem test type
This is a preparatory commit. In the future, we want to be able to setup alias mappings for area_src and area_dst in the shmem test, like we do in the hugetlb_shared test. With a VMA obtained via mmap(MAP_ANONYMOUS | MAP_SHARED), it isn't clear how to do this. So, mmap() with an fd, so we can create alias mappings. Use memfd_create instead of actually passing in a tmpfs path like hugetlb does, since it's more convenient / simpler to run, and works just as well. Future commits will: 1. Setup the alias mappings. 2. Extend our tests to actually take advantage of this, to test new userfaultfd behavior being introduced in this series. Also, a small fix in the area we're changing: when the hugetlb setup fails in main(), pass in the right argv[] so we actually print out the hugetlb file path. Link: https://lkml.kernel.org/r/20210302000133.272579-3-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit de45daecde2d4793e9021b102e168a4cb656dd03 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388147/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I63ac39245d4090e275238efa75bcdbd40fcc7879 |
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Axel Rasmussen
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1999a272c6 |
BACKPORT: FROMGIT: userfaultfd: support minor fault handling for shmem
Patch series "userfaultfd: support minor fault handling for shmem", v2. Overview ======== See my original series [1] for a detailed overview of minor fault handling in general. The feature in this series works exactly like the hugetblfs version (from userspace's perspective). I'm sending this as a separate series because: - The original minor fault handling series has a full set of R-Bs, and seems close to being merged. So, it seems reasonable to start looking at this next step, which extends the basic functionality. - shmem is different enough that this series may require some additional work before it's ready, and I don't want to delay the original series unnecessarily by bundling them together. Use Case ======== In some cases it is useful to have VM memory backed by tmpfs instead of hugetlbfs. So, this feature will be used to support the same VM live migration use case described in my original series. Additionally, Android folks (Lokesh Gidra <lokeshgidra@google.com>) hope to optimize the Android Runtime garbage collector using this feature: "The plan is to use userfaultfd for concurrently compacting the heap. With this feature, the heap can be shared-mapped at another location where the GC-thread(s) could continue the compaction operation without the need to invoke userfault ioctl(UFFDIO_COPY) each time. OTOH, if and when Java threads get faults on the heap, UFFDIO_CONTINUE can be used to resume execution. Furthermore, this feature enables updating references in the 'non-moving' portion of the heap efficiently. Without this feature, uneccessary page copying (ioctl(UFFDIO_COPY)) would be required." [1] https://lore.kernel.org/linux-fsdevel/20210301222728.176417-1-axelrasmussen@google.com/T/#t This patch (of 5): Modify the userfaultfd register API to allow registering shmem VMAs in minor mode. Modify the shmem mcopy implementation to support UFFDIO_CONTINUE in order to resolve such faults. Combine the shmem mcopy handler functions into a single shmem_mcopy_atomic_pte, which takes a mode parameter. This matches how the hugetlbfs implementation is structured, and lets us remove a good chunk of boilerplate. Link: https://lkml.kernel.org/r/20210302000133.272579-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210302000133.272579-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Wang Qing <wangqing@vivo.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 4cc6e15679966aa49afc5b114c3c83ba0ac39b05 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388146/ Conflicts: include/linux/shmem_fs.h mm/shmem.c mm/userfaultfd.c (1. write-protect related conflicts, rebased manually 2. Enclose shmem_mcopy_atomic_pte() with CONFIG_USERFAULTFD to avoid compile errors when USERFAULTFD is not enabled.) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: Idcd822b2a124a089121b9ad8c65061f6979126ec |
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Axel Rasmussen
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05004f0991 |
BACKPORT: FROMGIT: userfaultfd/selftests: add test exercising minor fault handling
Fix a dormant bug in userfaultfd_events_test(), where we did `return faulting_process(0)` instead of `exit(faulting_process(0))`. This caused the forked process to keep running, trying to execute any further test cases after the events test in parallel with the "real" process. Add a simple test case which exercises minor faults. In short, it does the following: 1. "Sets up" an area (area_dst) and a second shared mapping to the same underlying pages (area_dst_alias). 2. Register one of these areas with userfaultfd, in minor fault mode. 3. Start a second thread to handle any minor faults. 4. Populate the underlying pages with the non-UFFD-registered side of the mapping. Basically, memset() each page with some arbitrary contents. 5. Then, using the UFFD-registered mapping, read all of the page contents, asserting that the contents match expectations (we expect the minor fault handling thread can modify the page contents before resolving the fault). The minor fault handling thread, upon receiving an event, flips all the bits (~) in that page, just to prove that it can modify it in some arbitrary way. Then it issues a UFFDIO_CONTINUE ioctl, to setup the mapping and resolve the fault. The reading thread should wake up and see this modification. Currently the minor fault test is only enabled in hugetlb_shared mode, as this is the only configuration the kernel feature supports. Link: https://lkml.kernel.org/r/20210301222728.176417-7-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 823e78ae969c4ae9500cac5a84ee5b923634be4d https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388135/ Conflicts: tools/testing/selftests/vm/userfaultfd.c (Removed write-protect related test and removed uffd_stats usage) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I93a845d45436d835a4fd5de0dfd8a2c54fa15550 |
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Axel Rasmussen
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e896f54b5e |
BACKPORT: FROMGIT: userfaultfd: update documentation to describe minor fault handling
Reword / reorganize things a little bit into "lists", so new features / modes / ioctls can sort of just be appended. Describe how UFFDIO_REGISTER_MODE_MINOR and UFFDIO_CONTINUE can be used to intercept and resolve minor faults. Make it clear that COPY and ZEROPAGE are used for MISSING faults, whereas CONTINUE is used for MINOR faults. Link: https://lkml.kernel.org/r/20210301222728.176417-6-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit d08ba026886f0161e2bdd3dbd75c4da0fc62a284 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388137/ Conflicts: Documentation/admin-guide/mm/userfaultfd.rst (Manual rebase by removing text related to write-protect feature) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: Ib59504247d38034e4c86f692dd63f2b3706fe554 |
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Axel Rasmussen
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5d62f07fff |
BACKPORT: FROMGIT: userfaultfd: add UFFDIO_CONTINUE ioctl
This ioctl is how userspace ought to resolve "minor" userfaults. The
idea is, userspace is notified that a minor fault has occurred. It might
change the contents of the page using its second non-UFFD mapping, or
not. Then, it calls UFFDIO_CONTINUE to tell the kernel "I have ensured
the page contents are correct, carry on setting up the mapping".
Note that it doesn't make much sense to use UFFDIO_{COPY,ZEROPAGE} for
MINOR registered VMAs. ZEROPAGE maps the VMA to the zero page; but in
the minor fault case, we already have some pre-existing underlying page.
Likewise, UFFDIO_COPY isn't useful if we have a second non-UFFD mapping.
We'd just use memcpy() or similar instead.
It turns out hugetlb_mcopy_atomic_pte() already does very close to what
we want, if an existing page is provided via `struct page **pagep`. We
already special-case the behavior a bit for the UFFDIO_ZEROPAGE case, so
just extend that design: add an enum for the three modes of operation,
and make the small adjustments needed for the MCOPY_ATOMIC_CONTINUE
case. (Basically, look up the existing page, and avoid adding the
existing page to the page cache or calling set_page_huge_active() on
it.)
Link: https://lkml.kernel.org/r/20210301222728.176417-5-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Adam Ruprecht <ruprecht@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Cannon Matthews <cannonmatthews@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michal Koutn" <mkoutny@suse.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shawn Anastasio <shawn@anastas.io>
Cc: Steven Price <steven.price@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
(cherry picked from commit 14ea86439abaf3423cd9b6712ed5ce8451d2d181
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm)
Link: https://lore.kernel.org/patchwork/patch/1388136/
Conflicts: fs/userfaultfd.c
include/linux/hugetlb.h
include/linux/userfaultfd_k.h
include/uapi/linux/userfaultfd.h
mm/hugetlb.c
mm/userfaultfd.c
(1. 8f251a3d5ce3bdea73bd045ed35db64f32e0d0d9 is not cherry-picked yet so
switched SetHPageMigratable() to set_active_huge_page() in
mm/hugetlb.c,
2. Other files conflicts due to lack of write-protect userfaultfd
support. Manually rebased accordingly
3. Included linux/mm.h in linux/userfaultfd_k.h for definitions of
VM_UFFD_*)
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Bug: 160737021
Bug: 169683130
Change-Id: I45b62959dcb1d343154cb831113a26e47e77c8af
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Axel Rasmussen
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0bea3b8d35 |
BACKPORT: FROMGIT: userfaultfd: hugetlbfs: only compile UFFD helpers if config enabled
For background, mm/userfaultfd.c provides a general mcopy_atomic implementation. But some types of memory (i.e., hugetlb and shmem) need a slightly different implementation, so they provide their own helpers for this. In other words, userfaultfd is the only caller of these functions. This patch achieves two things: 1. Don't spend time compiling code which will end up never being referenced anyway (a small build time optimization). 2. In patches later in this series, we extend the signature of these helpers with UFFD-specific state (a mode enumeration). Once this happens, we *have to* either not compile the helpers, or unconditionally define the UFFD-only state (which seems messier to me). This includes the declarations in the headers, as otherwise they'd yield warnings about implicitly defining the type of those arguments. Link: https://lkml.kernel.org/r/20210301222728.176417-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 0e6e243e1d9a252c047c4cb1b032cfb31caf87ea https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388133/ Conflicts: include/linux/hugetlb.h (Manual rebase, required as 1f9dccb25b8fb48778149a002bb25d4ac2899633 isn't CP'ed) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I765cff74cde5fb4ce8141fb95e41848890ced961 |
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Axel Rasmussen
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84c481c854 |
FROMGIT: userfaultfd: disable huge PMD sharing for MINOR registered VMAs
As the comment says: for the MINOR fault use case, although the page might be present and populated in the other (non-UFFD-registered) half of the mapping, it may be out of date, and we explicitly want userspace to get a minor fault so it can check and potentially update the page's contents. Huge PMD sharing would prevent these faults from occurring for suitably aligned areas, so disable it upon UFFD registration. Link: https://lkml.kernel.org/r/20210301222728.176417-3-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 19fbec4445b6a690253c1785dfd376ede2cdb9d9 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388134/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I257024f980f43cf8b06b5421ee3278115d1b1540 |
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Axel Rasmussen
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59e978522d |
BACKPORT: FROMGIT: userfaultfd: add minor fault registration mode
Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 82a150ec394f6b944e26786b907fc0deab5b2064 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1388132/ Conflicts: arch/x86/Kconfig fs/userfaultfd.c include/linux/userfaultfd_k.h include/uapi/linux/userfaultfd.h init/Kconfig mm/hugetlb.c (Lack of userfaultfd write-protect support in 5.4 lead to all conflicts. Resolved by carefully rebasing such that write-protect related code doesn't get added) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I43b37272d531341439ceaa03213d0e2415e04688 |
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Peter Xu
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5f1b26c2cd |
BACKPORT: FROMGIT: hugetlb/userfaultfd: unshare all pmds for hugetlbfs when register wp
Huge pmd sharing for hugetlbfs is racy with userfaultfd-wp because userfaultfd-wp is always based on pgtable entries, so they cannot be shared. Walk the hugetlb range and unshare all such mappings if there is, right before UFFDIO_REGISTER will succeed and return to userspace. This will pair with want_pmd_share() in hugetlb code so that huge pmd sharing is completely disabled for userfaultfd-wp registered range. Link: https://lkml.kernel.org/r/20210218231206.15524-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 267bda5c9993856b86f91a998df632b29cf517e2 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1382208/ Conflicts: mm/hugetlb.c (CONFIG_CMA not CP'ed in this kernel. Manual rebase) Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I99d541ce45aaf924fa912f00dafa4caefe307755 |
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Peter Xu
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abc495fa9d |
FROMGIT: mm/hugetlb: move flush_hugetlb_tlb_range() into hugetlb.h
Prepare for it to be called outside of mm/hugetlb.c. Link: https://lkml.kernel.org/r/20210218231204.15474-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Adam Ruprecht <ruprecht@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Cannon Matthews <cannonmatthews@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: David Rientjes <rientjes@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michal Koutn" <mkoutny@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shawn Anastasio <shawn@anastas.io> Cc: Steven Price <steven.price@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 04297c667b3972097535638e3dab5a66f11ca1df https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1382206/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: I9bf21fe479548d44a8b611ed832b2f1af7667f4c |
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Peter Xu
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245a106b01 |
FROMGIT: mm/hugetlb: fix build with !ARCH_WANT_HUGE_PMD_SHARE
want_pmd_share() is undefined with !ARCH_WANT_HUGE_PMD_SHARE since it's put by accident into a "#ifdef ARCH_WANT_HUGE_PMD_SHARE" block. Moving it out won't work either since vma_shareable() is only defined within the block. Define it for !ARCH_WANT_HUGE_PMD_SHARE instead. Link: https://lkml.kernel.org/r/20210310185359.88297-1-peterx@redhat.com Fixes: 5b109cc1cdcc ("hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled") Signed-off-by: Peter Xu <peterx@redhat.com> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> (cherry picked from commit 5038f9dd8bbde13ff16435011bb3b0981acc5c1c https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1393174/ Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Bug: 160737021 Bug: 169683130 Change-Id: Id716afd43bff303f7eda2c4f70f18d9ea727c698 |
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Peter Xu
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a7279b3385 |
BACKPORT: FROMGIT: hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled
Huge pmd sharing could bring problem to userfaultfd. The thing is that
userfaultfd is running its logic based on the special bits on page table
entries, however the huge pmd sharing could potentially share page table
entries for different address ranges. That could cause issues on either:
- When sharing huge pmd page tables for an uffd write protected range, the
newly mapped huge pmd range will also be write protected unexpectedly, or,
- When we try to write protect a range of huge pmd shared range, we'll first
do huge_pmd_unshare() in hugetlb_change_protection(), however that also
means the UFFDIO_WRITEPROTECT could be silently skipped for the shared
region, which could lead to data loss.
Since at it, a few other things are done altogether:
- Move want_pmd_share() from mm/hugetlb.c into linux/hugetlb.h, because
that's definitely something that arch code would like to use too
- ARM64 currently directly check against CONFIG_ARCH_WANT_HUGE_PMD_SHARE when
trying to share huge pmd. Switch to the want_pmd_share() helper.
Since at it, move vma_shareable() from huge_pmd_share() into want_pmd_share().
Link: https://lkml.kernel.org/r/20210218231202.15426-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Adam Ruprecht <ruprecht@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Cannon Matthews <cannonmatthews@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michal Koutn" <mkoutny@suse.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shawn Anastasio <shawn@anastas.io>
Cc: Steven Price <steven.price@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
(cherry picked from commit ab6a0d00a63f92f1f0d220274fa989eb75c09f2b
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm)
Link: https://lore.kernel.org/patchwork/patch/1382207/
Conflicts:
include/linux/hugetlb.h
mm/hugetlb.c
(Manual rebase)
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Bug: 160737021
Bug: 169683130
Change-Id: Ie2dff7ab31600cae78914e3278be61516844394e
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