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https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git
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| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
David Hildenbrand
|
09e6bb5321 |
x86/mm/pat: fix VM_PAT handling in COW mappings
commit 04c35ab3bdae7fefbd7c7a7355f29fa03a035221 upstream.
PAT handling won't do the right thing in COW mappings: the first PTE (or,
in fact, all PTEs) can be replaced during write faults to point at anon
folios. Reliably recovering the correct PFN and cachemode using
follow_phys() from PTEs will not work in COW mappings.
Using follow_phys(), we might just get the address+protection of the anon
folio (which is very wrong), or fail on swap/nonswap entries, failing
follow_phys() and triggering a WARN_ON_ONCE() in untrack_pfn() and
track_pfn_copy(), not properly calling free_pfn_range().
In free_pfn_range(), we either wouldn't call memtype_free() or would call
it with the wrong range, possibly leaking memory.
To fix that, let's update follow_phys() to refuse returning anon folios,
and fallback to using the stored PFN inside vma->vm_pgoff for COW mappings
if we run into that.
We will now properly handle untrack_pfn() with COW mappings, where we
don't need the cachemode. We'll have to fail fork()->track_pfn_copy() if
the first page was replaced by an anon folio, though: we'd have to store
the cachemode in the VMA to make this work, likely growing the VMA size.
For now, lets keep it simple and let track_pfn_copy() just fail in that
case: it would have failed in the past with swap/nonswap entries already,
and it would have done the wrong thing with anon folios.
Simple reproducer to trigger the WARN_ON_ONCE() in untrack_pfn():
<--- C reproducer --->
#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>
#include <liburing.h>
int main(void)
{
struct io_uring_params p = {};
int ring_fd;
size_t size;
char *map;
ring_fd = io_uring_setup(1, &p);
if (ring_fd < 0) {
perror("io_uring_setup");
return 1;
}
size = p.sq_off.array + p.sq_entries * sizeof(unsigned);
/* Map the submission queue ring MAP_PRIVATE */
map = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
ring_fd, IORING_OFF_SQ_RING);
if (map == MAP_FAILED) {
perror("mmap");
return 1;
}
/* We have at least one page. Let's COW it. */
*map = 0;
pause();
return 0;
}
<--- C reproducer --->
On a system with 16 GiB RAM and swap configured:
# ./iouring &
# memhog 16G
# killall iouring
[ 301.552930] ------------[ cut here ]------------
[ 301.553285] WARNING: CPU: 7 PID: 1402 at arch/x86/mm/pat/memtype.c:1060 untrack_pfn+0xf4/0x100
[ 301.553989] Modules linked in: binfmt_misc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_g
[ 301.558232] CPU: 7 PID: 1402 Comm: iouring Not tainted 6.7.5-100.fc38.x86_64 #1
[ 301.558772] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebu4
[ 301.559569] RIP: 0010:untrack_pfn+0xf4/0x100
[ 301.559893] Code: 75 c4 eb cf 48 8b 43 10 8b a8 e8 00 00 00 3b 6b 28 74 b8 48 8b 7b 30 e8 ea 1a f7 000
[ 301.561189] RSP: 0018:ffffba2c0377fab8 EFLAGS: 00010282
[ 301.561590] RAX: 00000000ffffffea RBX: ffff9208c8ce9cc0 RCX: 000000010455e047
[ 301.562105] RDX: 07fffffff0eb1e0a RSI: 0000000000000000 RDI: ffff9208c391d200
[ 301.562628] RBP: 0000000000000000 R08: ffffba2c0377fab8 R09: 0000000000000000
[ 301.563145] R10: ffff9208d2292d50 R11: 0000000000000002 R12: 00007fea890e0000
[ 301.563669] R13: 0000000000000000 R14: ffffba2c0377fc08 R15: 0000000000000000
[ 301.564186] FS: 0000000000000000(0000) GS:ffff920c2fbc0000(0000) knlGS:0000000000000000
[ 301.564773] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 301.565197] CR2: 00007fea88ee8a20 CR3: 00000001033a8000 CR4: 0000000000750ef0
[ 301.565725] PKRU: 55555554
[ 301.565944] Call Trace:
[ 301.566148] <TASK>
[ 301.566325] ? untrack_pfn+0xf4/0x100
[ 301.566618] ? __warn+0x81/0x130
[ 301.566876] ? untrack_pfn+0xf4/0x100
[ 301.567163] ? report_bug+0x171/0x1a0
[ 301.567466] ? handle_bug+0x3c/0x80
[ 301.567743] ? exc_invalid_op+0x17/0x70
[ 301.568038] ? asm_exc_invalid_op+0x1a/0x20
[ 301.568363] ? untrack_pfn+0xf4/0x100
[ 301.568660] ? untrack_pfn+0x65/0x100
[ 301.568947] unmap_single_vma+0xa6/0xe0
[ 301.569247] unmap_vmas+0xb5/0x190
[ 301.569532] exit_mmap+0xec/0x340
[ 301.569801] __mmput+0x3e/0x130
[ 301.570051] do_exit+0x305/0xaf0
...
Link: https://lkml.kernel.org/r/20240403212131.929421-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Wupeng Ma <mawupeng1@huawei.com>
Closes: https://lkml.kernel.org/r/20240227122814.3781907-1-mawupeng1@huawei.com
Fixes:
|
||
Vlastimil Babka
|
ab81b3d2f3 |
mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations
commit 803de9000f334b771afacb6ff3e78622916668b0 upstream.
Sven reports an infinite loop in __alloc_pages_slowpath() for costly order
__GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination
can happen in a suspend/resume context where a GFP_KERNEL allocation can
have __GFP_IO masked out via gfp_allowed_mask.
Quoting Sven:
1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER)
with __GFP_RETRY_MAYFAIL set.
2. page alloc's __alloc_pages_slowpath tries to get a page from the
freelist. This fails because there is nothing free of that costly
order.
3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim,
which bails out because a zone is ready to be compacted; it pretends
to have made a single page of progress.
4. page alloc tries to compact, but this always bails out early because
__GFP_IO is not set (it's not passed by the snd allocator, and even
if it were, we are suspending so the __GFP_IO flag would be cleared
anyway).
5. page alloc believes reclaim progress was made (because of the
pretense in item 3) and so it checks whether it should retry
compaction. The compaction retry logic thinks it should try again,
because:
a) reclaim is needed because of the early bail-out in item 4
b) a zonelist is suitable for compaction
6. goto 2. indefinite stall.
(end quote)
The immediate root cause is confusing the COMPACT_SKIPPED returned from
__alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be
indicating a lack of order-0 pages, and in step 5 evaluating that in
should_compact_retry() as a reason to retry, before incrementing and
limiting the number of retries. There are however other places that
wrongly assume that compaction can happen while we lack __GFP_IO.
To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO
evaluation and switch the open-coded test in try_to_compact_pages() to use
it.
Also use the new helper in:
- compaction_ready(), which will make reclaim not bail out in step 3, so
there's at least one attempt to actually reclaim, even if chances are
small for a costly order
- in_reclaim_compaction() which will make should_continue_reclaim()
return false and we don't over-reclaim unnecessarily
- in __alloc_pages_slowpath() to set a local variable can_compact,
which is then used to avoid retrying reclaim/compaction for costly
allocations (step 5) if we can't compact and also to skip the early
compaction attempt that we do in some cases
Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz
Fixes:
|
||
Zi Yan
|
747d4ee747 |
mm/migrate: set swap entry values of THP tail pages properly.
The tail pages in a THP can have swap entry information stored in their
private field. When migrating to a new page, all tail pages of the new
page need to update ->private to avoid future data corruption.
This fix is stable-only, since after commit 07e09c483cbe ("mm/huge_memory:
work on folio->swap instead of page->private when splitting folio"),
subpages of a swapcached THP no longer requires the maintenance.
Adding THPs to the swapcache was introduced in commit
|
||
Liu Shixin
|
7f75e937ec |
mm/memory-failure: fix an incorrect use of tail pages
When backport commit c79c5a0a00a9 to 5.4-stable, there is a mistake change.
The head page instead of tail page should be passed to try_to_unmap(),
otherwise unmap will failed as follows.
Memory failure: 0x121c10: failed to unmap page (mapcount=1)
Memory failure: 0x121c10: recovery action for unmapping failed page: Ignored
Fixes:
|
||
Qiang Zhang
|
f2cee08a69 |
memtest: use {READ,WRITE}_ONCE in memory scanning
[ Upstream commit 82634d7e24271698e50a3ec811e5f50de790a65f ]
memtest failed to find bad memory when compiled with clang. So use
{WRITE,READ}_ONCE to access memory to avoid compiler over optimization.
Link: https://lkml.kernel.org/r/20240312080422.691222-1-qiang4.zhang@intel.com
Signed-off-by: Qiang Zhang <qiang4.zhang@intel.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
||
Lokesh Gidra
|
429aaf144b |
userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb
commit 67695f18d55924b2013534ef3bdc363bc9e14605 upstream.
In mfill_atomic_hugetlb(), mmap_changing isn't being checked
again if we drop mmap_lock and reacquire it. When the lock is not held,
mmap_changing could have been incremented. This is also inconsistent
with the behavior in mfill_atomic().
Link: https://lkml.kernel.org/r/20240117223729.1444522-1-lokeshgidra@google.com
Fixes:
|
||
GONG, Ruiqi
|
febd743200 |
memcg: add refcnt for pcpu stock to avoid UAF problem in drain_all_stock()
commit 1a3e1f40962c445b997151a542314f3c6097f8c3 upstream.
NOTE: This is a partial backport since we only need the refcnt between
memcg and stock to fix the problem stated below, and in this way
multiple versions use the same code and align with each other.
There was a kernel panic happened on an in-house environment running
3.10, and the same problem was reproduced on 4.19:
general protection fault: 0000 [#1] SMP PTI
CPU: 1 PID: 2085 Comm: bash Kdump: loaded Tainted: G L 4.19.90+ #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
RIP: 0010 drain_all_stock+0xad/0x140
Code: 00 00 4d 85 ff 74 2c 45 85 c9 74 27 4d 39 fc 74 42 41 80 bc 24 28 04 00 00 00 74 17 49 8b 04 24 49 8b 17 48 8b 88 90 02 00 00 <48> 39 8a 90 02 00 00 74 02 eb 86 48 63 88 3c 01 00 00 39 8a 3c 01
RSP: 0018:ffffa7efc5813d70 EFLAGS: 00010202
RAX: ffff8cb185548800 RBX: ffff8cb89f420160 RCX: ffff8cb1867b6000
RDX: babababababababa RSI: 0000000000000001 RDI: 0000000000231876
RBP: 0000000000000000 R08: 0000000000000415 R09: 0000000000000002
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8cb186f89040
R13: 0000000000020160 R14: 0000000000000001 R15: ffff8cb186b27040
FS: 00007f4a308d3740(0000) GS:ffff8cb89f440000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe4d634a68 CR3: 000000010b022000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
mem_cgroup_force_empty_write+0x31/0xb0
cgroup_file_write+0x60/0x140
? __check_object_size+0x136/0x147
kernfs_fop_write+0x10e/0x190
__vfs_write+0x37/0x1b0
? selinux_file_permission+0xe8/0x130
? security_file_permission+0x2e/0xb0
vfs_write+0xb6/0x1a0
ksys_write+0x57/0xd0
do_syscall_64+0x63/0x250
? async_page_fault+0x8/0x30
entry_SYSCALL_64_after_hwframe+0x5c/0xc1
Modules linked in: ...
It is found that in case of stock->nr_pages == 0, the memcg on
stock->cached could be freed due to its refcnt decreased to 0, which
made stock->cached become a dangling pointer. It could cause a UAF
problem in drain_all_stock() in the following concurrent scenario. Note
that drain_all_stock() doesn't disable irq but only preemption.
CPU1 CPU2
==============================================================================
stock->cached = memcgA (freed)
drain_all_stock(memcgB)
rcu_read_lock()
memcg = CPU1's stock->cached (memcgA)
(interrupted)
refill_stock(memcgC)
drain_stock(memcgA)
stock->cached = memcgC
stock->nr_pages += xxx (> 0)
stock->nr_pages > 0
mem_cgroup_is_descendant(memcgA, memcgB) [UAF]
rcu_read_unlock()
This problem is, unintentionally, fixed at 5.9, where commit
1a3e1f40962c ("mm: memcontrol: decouple reference counting from page
accounting") adds memcg refcnt for stock. Therefore affected LTS
versions include 4.19 and 5.4.
For 4.19, memcg's css offline process doesn't call drain_all_stock(). so
it's easier for the released memcg to be left on the stock. For 5.4,
although mem_cgroup_css_offline() does call drain_all_stock(), but the
flushing could be skipped when stock->nr_pages happens to be 0, and
besides the async draining could be delayed and take place after the UAF
problem has happened.
Fix this problem by adding (and decreasing) memcg's refcnt when memcg is
put onto (and removed from) stock, just like how commit 1a3e1f40962c
("mm: memcontrol: decouple reference counting from page accounting")
does. After all, "being on the stock" is a kind of reference with
regards to memcg. As such, it's guaranteed that a css on stock would not
be freed.
It's good to mention that refill_stock() is executed in an irq-disabled
context, so the drain_stock() patched with css_put() would not actually
free memcgA until the end of refill_stock(), since css_put() is an RCU
free and it's still in grace period. For CPU2, the access to CPU1's
stock->cached is protected by rcu_read_lock(), so in this case it gets
either NULL from stock->cached or a memcgA that is still good.
Cc: stable@vger.kernel.org # 4.19 5.4
Fixes:
|
||
Zach O'Keefe
|
1f12e4b328 |
mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again
commit 9319b647902cbd5cc884ac08a8a6d54ce111fc78 upstream.
(struct dirty_throttle_control *)->thresh is an unsigned long, but is
passed as the u32 divisor argument to div_u64(). On architectures where
unsigned long is 64 bytes, the argument will be implicitly truncated.
Use div64_u64() instead of div_u64() so that the value used in the "is
this a safe division" check is the same as the divisor.
Also, remove redundant cast of the numerator to u64, as that should happen
implicitly.
This would be difficult to exploit in memcg domain, given the ratio-based
arithmetic domain_drity_limits() uses, but is much easier in global
writeback domain with a BDI_CAP_STRICTLIMIT-backing device, using e.g.
vm.dirty_bytes=(1<<32)*PAGE_SIZE so that dtc->thresh == (1<<32)
Link: https://lkml.kernel.org/r/20240118181954.1415197-1-zokeefe@google.com
Fixes:
|
||
Jiajun Xie
|
77359c4973 |
mm: fix unmap_mapping_range high bits shift bug
commit 9eab0421fa94a3dde0d1f7e36ab3294fc306c99d upstream.
The bug happens when highest bit of holebegin is 1, suppose holebegin is
0x8000000111111000, after shift, hba would be 0xfff8000000111111, then
vma_interval_tree_foreach would look it up fail or leads to the wrong
result.
error call seq e.g.:
- mmap(..., offset=0x8000000111111000)
|- syscall(mmap, ... unsigned long, off):
|- ksys_mmap_pgoff( ... , off >> PAGE_SHIFT);
here pgoff is correctly shifted to 0x8000000111111,
but pass 0x8000000111111000 as holebegin to unmap
would then cause terrible result, as shown below:
- unmap_mapping_range(..., loff_t const holebegin)
|- pgoff_t hba = holebegin >> PAGE_SHIFT;
/* hba = 0xfff8000000111111 unexpectedly */
The issue happens in Heterogeneous computing, where the device(e.g.
gpu) and host share the same virtual address space.
A simple workflow pattern which hit the issue is:
/* host */
1. userspace first mmap a file backed VA range with specified offset.
e.g. (offset=0x800..., mmap return: va_a)
2. write some data to the corresponding sys page
e.g. (va_a = 0xAABB)
/* device */
3. gpu workload touches VA, triggers gpu fault and notify the host.
/* host */
4. reviced gpu fault notification, then it will:
4.1 unmap host pages and also takes care of cpu tlb
(use unmap_mapping_range with offset=0x800...)
4.2 migrate sys page to device
4.3 setup device page table and resolve device fault.
/* device */
5. gpu workload continued, it accessed va_a and got 0xAABB.
6. gpu workload continued, it wrote 0xBBCC to va_a.
/* host */
7. userspace access va_a, as expected, it will:
7.1 trigger cpu vm fault.
7.2 driver handling fault to migrate gpu local page to host.
8. userspace then could correctly get 0xBBCC from va_a
9. done
But in step 4.1, if we hit the bug this patch mentioned, then userspace
would never trigger cpu fault, and still get the old value: 0xAABB.
Making holebegin unsigned first fixes the bug.
Link: https://lkml.kernel.org/r/20231220052839.26970-1-jiajun.xie.sh@gmail.com
Signed-off-by: Jiajun Xie <jiajun.xie.sh@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
Matthew Wilcox (Oracle)
|
85015a96bc |
mm/memory-failure: check the mapcount of the precise page
[ Upstream commit c79c5a0a00a9457718056b588f312baadf44e471 ]
A process may map only some of the pages in a folio, and might be missed
if it maps the poisoned page but not the head page. Or it might be
unnecessarily hit if it maps the head page, but not the poisoned page.
Link: https://lkml.kernel.org/r/20231218135837.3310403-3-willy@infradead.org
Fixes:
|
||
|
Zi Yan
|
ad6941b192 |
mm/cma: use nth_page() in place of direct struct page manipulation
commit 2e7cfe5cd5b6b0b98abf57a3074885979e187c1c upstream.
Patch series "Use nth_page() in place of direct struct page manipulation",
v3.
On SPARSEMEM without VMEMMAP, struct page is not guaranteed to be
contiguous, since each memory section's memmap might be allocated
independently. hugetlb pages can go beyond a memory section size, thus
direct struct page manipulation on hugetlb pages/subpages might give wrong
struct page. Kernel provides nth_page() to do the manipulation properly.
Use that whenever code can see hugetlb pages.
This patch (of 5):
When dealing with hugetlb pages, manipulating struct page pointers
directly can get to wrong struct page, since struct page is not guaranteed
to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle
it properly.
Without the fix, page_kasan_tag_reset() could reset wrong page tags,
causing a wrong kasan result. No related bug is reported. The fix
comes from code inspection.
Link: https://lkml.kernel.org/r/20230913201248.452081-1-zi.yan@sent.com
Link: https://lkml.kernel.org/r/20230913201248.452081-2-zi.yan@sent.com
Fixes:
|
||
Reuben Hawkins
|
3718a48ef4 |
vfs: fix readahead(2) on block devices
[ Upstream commit 7116c0af4b8414b2f19fdb366eea213cbd9d91c2 ]
Readahead was factored to call generic_fadvise. That refactor added an
S_ISREG restriction which broke readahead on block devices.
In addition to S_ISREG, this change checks S_ISBLK to fix block device
readahead. There is no change in behavior with any file type besides block
devices in this change.
Fixes:
|
||
Christian Brauner
|
5d3975e36c |
tmpfs: verify {g,u}id mount options correctly
[ Upstream commit 0200679fc7953177941e41c2a4241d0b6c2c5de8 ]
A while ago we received the following report:
"The other outstanding issue I noticed comes from the fact that
fsconfig syscalls may occur in a different userns than that which
called fsopen. That means that resolving the uid/gid via
current_user_ns() can save a kuid that isn't mapped in the associated
namespace when the filesystem is finally mounted. This means that it
is possible for an unprivileged user to create files owned by any
group in a tmpfs mount (since we can set the SUID bit on the tmpfs
directory), or a tmpfs that is owned by any user, including the root
group/user."
The contract for {g,u}id mount options and {g,u}id values in general set
from userspace has always been that they are translated according to the
caller's idmapping. In so far, tmpfs has been doing the correct thing.
But since tmpfs is mountable in unprivileged contexts it is also
necessary to verify that the resulting {k,g}uid is representable in the
namespace of the superblock to avoid such bugs as above.
The new mount api's cross-namespace delegation abilities are already
widely used. After having talked to a bunch of userspace this is the
most faithful solution with minimal regression risks. I know of one
users - systemd - that makes use of the new mount api in this way and
they don't set unresolable {g,u}ids. So the regression risk is minimal.
Link: https://lore.kernel.org/lkml/CALxfFW4BXhEwxR0Q5LSkg-8Vb4r2MONKCcUCVioehXQKr35eHg@mail.gmail.com
Fixes:
|
||
Linus Torvalds
|
c404e1e197 |
mm: allow a controlled amount of unfairness in the page lock
commit 5ef64cc8987a9211d3f3667331ba3411a94ddc79 upstream.
Commit 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic") made
the page locking entirely fair, in that if a waiter came in while the
lock was held, the lock would be transferred to the lockers strictly in
order.
That was intended to finally get rid of the long-reported watchdog
failures that involved the page lock under extreme load, where a process
could end up waiting essentially forever, as other page lockers stole
the lock from under it.
It also improved some benchmarks, but it ended up causing huge
performance regressions on others, simply because fair lock behavior
doesn't end up giving out the lock as aggressively, causing better
worst-case latency, but potentially much worse average latencies and
throughput.
Instead of reverting that change entirely, this introduces a controlled
amount of unfairness, with a sysctl knob to tune it if somebody needs
to. But the default value should hopefully be good for any normal load,
allowing a few rounds of lock stealing, but enforcing the strict
ordering before the lock has been stolen too many times.
There is also a hint from Matthieu Baerts that the fair page coloring
may end up exposing an ABBA deadlock that is hidden by the usual
optimistic lock stealing, and while the unfairness doesn't fix the
fundamental issue (and I'm still looking at that), it avoids it in
practice.
The amount of unfairness can be modified by writing a new value to the
'sysctl_page_lock_unfairness' variable (default value of 5, exposed
through /proc/sys/vm/page_lock_unfairness), but that is hopefully
something we'd use mainly for debugging rather than being necessary for
any deep system tuning.
This whole issue has exposed just how critical the page lock can be, and
how contended it gets under certain locks. And the main contention
doesn't really seem to be anything related to IO (which was the origin
of this lock), but for things like just verifying that the page file
mapping is stable while faulting in the page into a page table.
Link: https://lore.kernel.org/linux-fsdevel/ed8442fd-6f54-dd84-cd4a-941e8b7ee603@MichaelLarabel.com/
Link: https://www.phoronix.com/scan.php?page=article&item=linux-50-59&num=1
Link: https://lore.kernel.org/linux-fsdevel/c560a38d-8313-51fb-b1ec-e904bd8836bc@tessares.net/
Reported-and-tested-by: Michael Larabel <Michael@michaellarabel.com>
Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@oracle.com>
Tested-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
|
Linus Torvalds
|
72ab3d39b4 |
mm: make wait_on_page_writeback() wait for multiple pending writebacks
commit c2407cf7d22d0c0d94cf20342b3b8f06f1d904e7 upstream.
Ever since commit 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common()
logic") we've had some very occasional reports of BUG_ON(PageWriteback)
in write_cache_pages(), which we thought we already fixed in commit
073861ed77b6 ("mm: fix VM_BUG_ON(PageTail) and BUG_ON(PageWriteback)").
But syzbot just reported another one, even with that commit in place.
And it turns out that there's a simpler way to trigger the BUG_ON() than
the one Hugh found with page re-use. It all boils down to the fact that
the page writeback is ostensibly serialized by the page lock, but that
isn't actually really true.
Yes, the people _setting_ writeback all do so under the page lock, but
the actual clearing of the bit - and waking up any waiters - happens
without any page lock.
This gives us this fairly simple race condition:
CPU1 = end previous writeback
CPU2 = start new writeback under page lock
CPU3 = write_cache_pages()
CPU1 CPU2 CPU3
---- ---- ----
end_page_writeback()
test_clear_page_writeback(page)
... delayed...
lock_page();
set_page_writeback()
unlock_page()
lock_page()
wait_on_page_writeback();
wake_up_page(page, PG_writeback);
.. wakes up CPU3 ..
BUG_ON(PageWriteback(page));
where the BUG_ON() happens because we woke up the PG_writeback bit
becasue of the _previous_ writeback, but a new one had already been
started because the clearing of the bit wasn't actually atomic wrt the
actual wakeup or serialized by the page lock.
The reason this didn't use to happen was that the old logic in waiting
on a page bit would just loop if it ever saw the bit set again.
The nice proper fix would probably be to get rid of the whole "wait for
writeback to clear, and then set it" logic in the writeback path, and
replace it with an atomic "wait-to-set" (ie the same as we have for page
locking: we set the page lock bit with a single "lock_page()", not with
"wait for lock bit to clear and then set it").
However, out current model for writeback is that the waiting for the
writeback bit is done by the generic VFS code (ie write_cache_pages()),
but the actual setting of the writeback bit is done much later by the
filesystem ".writepages()" function.
IOW, to make the writeback bit have that same kind of "wait-to-set"
behavior as we have for page locking, we'd have to change our roughly
~50 different writeback functions. Painful.
Instead, just make "wait_on_page_writeback()" loop on the very unlikely
situation that the PG_writeback bit is still set, basically re-instating
the old behavior. This is very non-optimal in case of contention, but
since we only ever set the bit under the page lock, that situation is
controlled.
Reported-by: syzbot+2fc0712f8f8b8b8fa0ef@syzkaller.appspotmail.com
Fixes: 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic")
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
Hugh Dickins
|
9ea42ba3e6 |
mm: fix VM_BUG_ON(PageTail) and BUG_ON(PageWriteback)
commit 073861ed77b6b957c3c8d54a11dc503f7d986ceb upstream. Twice now, when exercising ext4 looped on shmem huge pages, I have crashed on the PF_ONLY_HEAD check inside PageWaiters(): ext4_finish_bio() calling end_page_writeback() calling wake_up_page() on tail of a shmem huge page, no longer an ext4 page at all. The problem is that PageWriteback is not accompanied by a page reference (as the NOTE at the end of test_clear_page_writeback() acknowledges): as soon as TestClearPageWriteback has been done, that page could be removed from page cache, freed, and reused for something else by the time that wake_up_page() is reached. https://lore.kernel.org/linux-mm/20200827122019.GC14765@casper.infradead.org/ Matthew Wilcox suggested avoiding or weakening the PageWaiters() tail check; but I'm paranoid about even looking at an unreferenced struct page, lest its memory might itself have already been reused or hotremoved (and wake_up_page_bit() may modify that memory with its ClearPageWaiters()). Then on crashing a second time, realized there's a stronger reason against that approach. If my testing just occasionally crashes on that check, when the page is reused for part of a compound page, wouldn't it be much more common for the page to get reused as an order-0 page before reaching wake_up_page()? And on rare occasions, might that reused page already be marked PageWriteback by its new user, and already be waited upon? What would that look like? It would look like BUG_ON(PageWriteback) after wait_on_page_writeback() in write_cache_pages() (though I have never seen that crash myself). Matthew Wilcox explaining this to himself: "page is allocated, added to page cache, dirtied, writeback starts, --- thread A --- filesystem calls end_page_writeback() test_clear_page_writeback() --- context switch to thread B --- truncate_inode_pages_range() finds the page, it doesn't have writeback set, we delete it from the page cache. Page gets reallocated, dirtied, writeback starts again. Then we call write_cache_pages(), see PageWriteback() set, call wait_on_page_writeback() --- context switch back to thread A --- wake_up_page(page, PG_writeback); ... thread B is woken, but because the wakeup was for the old use of the page, PageWriteback is still set. Devious" And prior to 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic") this would have been much less likely: before that, wake_page_function()'s non-exclusive case would stop walking and not wake if it found Writeback already set again; whereas now the non-exclusive case proceeds to wake. I have not thought of a fix that does not add a little overhead: the simplest fix is for end_page_writeback() to get_page() before calling test_clear_page_writeback(), then put_page() after wake_up_page(). Was there a chance of missed wakeups before, since a page freed before reaching wake_up_page() would have PageWaiters cleared? I think not, because each waiter does hold a reference on the page. This bug comes when the old use of the page, the one we do TestClearPageWriteback on, had *no* waiters, so no additional page reference beyond the page cache (and whoever racily freed it). The reuse of the page has a waiter holding a reference, and its own PageWriteback set; but the belated wake_up_page() has woken the reuse to hit that BUG_ON(PageWriteback). Reported-by: syzbot+3622cea378100f45d59f@syzkaller.appspotmail.com Reported-by: Qian Cai <cai@lca.pw> Fixes: 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: stable@vger.kernel.org # v5.8+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|
Linus Torvalds
|
e77e5481d5 |
list: add "list_del_init_careful()" to go with "list_empty_careful()"
[ Upstream commit c6fe44d96fc1536af5b11cd859686453d1b7bfd1 ]
That gives us ordering guarantees around the pair.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stable-dep-of: 2192bba03d80 ("epoll: ep_autoremove_wake_function should use list_del_init_careful")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
||
|
Linus Torvalds
|
c32ab1c195 |
mm: rewrite wait_on_page_bit_common() logic
[ Upstream commit 2a9127fcf2296674d58024f83981f40b128fffea ] It turns out that wait_on_page_bit_common() had several problems, ranging from just unfair behavioe due to re-queueing at the end of the wait queue when re-trying, and an outright bug that could result in missed wakeups (but probably never happened in practice). This rewrites the whole logic to avoid both issues, by simply moving the logic to check (and possibly take) the bit lock into the wakeup path instead. That makes everything much more straightforward, and means that we never need to re-queue the wait entry: if we get woken up, we'll be notified through WQ_FLAG_WOKEN, and the wait queue entry will have been removed, and everything will have been done for us. Link: https://lore.kernel.org/lkml/CAHk-=wjJA2Z3kUFb-5s=6+n0qbTs8ELqKFt9B3pH85a8fGD73w@mail.gmail.com/ Link: https://lore.kernel.org/lkml/alpine.LSU.2.11.2007221359450.1017@eggly.anvils/ Reported-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Stable-dep-of: 2192bba03d80 ("epoll: ep_autoremove_wake_function should use list_del_init_careful") Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
Kees Cook
|
0638dcc7e7 |
treewide: Remove uninitialized_var() usage
commit 3f649ab728cda8038259d8f14492fe400fbab911 upstream. Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
Tetsuo Handa
|
93ca0d7b88 |
mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock
commit 1007843a91909a4995ee78a538f62d8665705b66 upstream.
syzbot is reporting circular locking dependency which involves
zonelist_update_seq seqlock [1], for this lock is checked by memory
allocation requests which do not need to be retried.
One deadlock scenario is kmalloc(GFP_ATOMIC) from an interrupt handler.
CPU0
----
__build_all_zonelists() {
write_seqlock(&zonelist_update_seq); // makes zonelist_update_seq.seqcount odd
// e.g. timer interrupt handler runs at this moment
some_timer_func() {
kmalloc(GFP_ATOMIC) {
__alloc_pages_slowpath() {
read_seqbegin(&zonelist_update_seq) {
// spins forever because zonelist_update_seq.seqcount is odd
}
}
}
}
// e.g. timer interrupt handler finishes
write_sequnlock(&zonelist_update_seq); // makes zonelist_update_seq.seqcount even
}
This deadlock scenario can be easily eliminated by not calling
read_seqbegin(&zonelist_update_seq) from !__GFP_DIRECT_RECLAIM allocation
requests, for retry is applicable to only __GFP_DIRECT_RECLAIM allocation
requests. But Michal Hocko does not know whether we should go with this
approach.
Another deadlock scenario which syzbot is reporting is a race between
kmalloc(GFP_ATOMIC) from tty_insert_flip_string_and_push_buffer() with
port->lock held and printk() from __build_all_zonelists() with
zonelist_update_seq held.
CPU0 CPU1
---- ----
pty_write() {
tty_insert_flip_string_and_push_buffer() {
__build_all_zonelists() {
write_seqlock(&zonelist_update_seq);
build_zonelists() {
printk() {
vprintk() {
vprintk_default() {
vprintk_emit() {
console_unlock() {
console_flush_all() {
console_emit_next_record() {
con->write() = serial8250_console_write() {
spin_lock_irqsave(&port->lock, flags);
tty_insert_flip_string() {
tty_insert_flip_string_fixed_flag() {
__tty_buffer_request_room() {
tty_buffer_alloc() {
kmalloc(GFP_ATOMIC | __GFP_NOWARN) {
__alloc_pages_slowpath() {
zonelist_iter_begin() {
read_seqbegin(&zonelist_update_seq); // spins forever because zonelist_update_seq.seqcount is odd
spin_lock_irqsave(&port->lock, flags); // spins forever because port->lock is held
}
}
}
}
}
}
}
}
spin_unlock_irqrestore(&port->lock, flags);
// message is printed to console
spin_unlock_irqrestore(&port->lock, flags);
}
}
}
}
}
}
}
}
}
write_sequnlock(&zonelist_update_seq);
}
}
}
This deadlock scenario can be eliminated by
preventing interrupt context from calling kmalloc(GFP_ATOMIC)
and
preventing printk() from calling console_flush_all()
while zonelist_update_seq.seqcount is odd.
Since Petr Mladek thinks that __build_all_zonelists() can become a
candidate for deferring printk() [2], let's address this problem by
disabling local interrupts in order to avoid kmalloc(GFP_ATOMIC)
and
disabling synchronous printk() in order to avoid console_flush_all()
.
As a side effect of minimizing duration of zonelist_update_seq.seqcount
being odd by disabling synchronous printk(), latency at
read_seqbegin(&zonelist_update_seq) for both !__GFP_DIRECT_RECLAIM and
__GFP_DIRECT_RECLAIM allocation requests will be reduced. Although, from
lockdep perspective, not calling read_seqbegin(&zonelist_update_seq) (i.e.
do not record unnecessary locking dependency) from interrupt context is
still preferable, even if we don't allow calling kmalloc(GFP_ATOMIC)
inside
write_seqlock(&zonelist_update_seq)/write_sequnlock(&zonelist_update_seq)
section...
Link: https://lkml.kernel.org/r/8796b95c-3da3-5885-fddd-6ef55f30e4d3@I-love.SAKURA.ne.jp
Fixes: 3d36424b3b58 ("mm/page_alloc: fix race condition between build_all_zonelists and page allocation")
Link: https://lkml.kernel.org/r/ZCrs+1cDqPWTDFNM@alley [2]
Reported-by: syzbot <syzbot+223c7461c58c58a4cb10@syzkaller.appspotmail.com>
Link: https://syzkaller.appspot.com/bug?extid=223c7461c58c58a4cb10 [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Petr Mladek <pmladek@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Patrick Daly <quic_pdaly@quicinc.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
Rongwei Wang
|
e7bba7ddb4 |
mm/swap: fix swap_info_struct race between swapoff and get_swap_pages()
commit 6fe7d6b992113719e96744d974212df3fcddc76c upstream.
The si->lock must be held when deleting the si from the available list.
Otherwise, another thread can re-add the si to the available list, which
can lead to memory corruption. The only place we have found where this
happens is in the swapoff path. This case can be described as below:
core 0 core 1
swapoff
del_from_avail_list(si) waiting
try lock si->lock acquire swap_avail_lock
and re-add si into
swap_avail_head
acquire si->lock but missing si already being added again, and continuing
to clear SWP_WRITEOK, etc.
It can be easily found that a massive warning messages can be triggered
inside get_swap_pages() by some special cases, for example, we call
madvise(MADV_PAGEOUT) on blocks of touched memory concurrently, meanwhile,
run much swapon-swapoff operations (e.g. stress-ng-swap).
However, in the worst case, panic can be caused by the above scene. In
swapoff(), the memory used by si could be kept in swap_info[] after
turning off a swap. This means memory corruption will not be caused
immediately until allocated and reset for a new swap in the swapon path.
A panic message caused: (with CONFIG_PLIST_DEBUG enabled)
------------[ cut here ]------------
top: 00000000e58a3003, n: 0000000013e75cda, p: 000000008cd4451a
prev: 0000000035b1e58a, n: 000000008cd4451a, p: 000000002150ee8d
next: 000000008cd4451a, n: 000000008cd4451a, p: 000000008cd4451a
WARNING: CPU: 21 PID: 1843 at lib/plist.c:60 plist_check_prev_next_node+0x50/0x70
Modules linked in: rfkill(E) crct10dif_ce(E)...
CPU: 21 PID: 1843 Comm: stress-ng Kdump: ... 5.10.134+
Hardware name: Alibaba Cloud ECS, BIOS 0.0.0 02/06/2015
pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)
pc : plist_check_prev_next_node+0x50/0x70
lr : plist_check_prev_next_node+0x50/0x70
sp : ffff0018009d3c30
x29: ffff0018009d3c40 x28: ffff800011b32a98
x27: 0000000000000000 x26: ffff001803908000
x25: ffff8000128ea088 x24: ffff800011b32a48
x23: 0000000000000028 x22: ffff001800875c00
x21: ffff800010f9e520 x20: ffff001800875c00
x19: ffff001800fdc6e0 x18: 0000000000000030
x17: 0000000000000000 x16: 0000000000000000
x15: 0736076307640766 x14: 0730073007380731
x13: 0736076307640766 x12: 0730073007380731
x11: 000000000004058d x10: 0000000085a85b76
x9 : ffff8000101436e4 x8 : ffff800011c8ce08
x7 : 0000000000000000 x6 : 0000000000000001
x5 : ffff0017df9ed338 x4 : 0000000000000001
x3 : ffff8017ce62a000 x2 : ffff0017df9ed340
x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
plist_check_prev_next_node+0x50/0x70
plist_check_head+0x80/0xf0
plist_add+0x28/0x140
add_to_avail_list+0x9c/0xf0
_enable_swap_info+0x78/0xb4
__do_sys_swapon+0x918/0xa10
__arm64_sys_swapon+0x20/0x30
el0_svc_common+0x8c/0x220
do_el0_svc+0x2c/0x90
el0_svc+0x1c/0x30
el0_sync_handler+0xa8/0xb0
el0_sync+0x148/0x180
irq event stamp: 2082270
Now, si->lock locked before calling 'del_from_avail_list()' to make sure
other thread see the si had been deleted and SWP_WRITEOK cleared together,
will not reinsert again.
This problem exists in versions after stable 5.10.y.
Link: https://lkml.kernel.org/r/20230404154716.23058-1-rongwei.wang@linux.alibaba.com
Fixes:
|
||
Yin Fengwei
|
b53d209d71 |
mm/thp: check and bail out if page in deferred queue already
commit 81e506bec9be1eceaf5a2c654e28ba5176ef48d8 upstream. Kernel build regression with LLVM was reported here: https://lore.kernel.org/all/Y1GCYXGtEVZbcv%2F5@dev-arch.thelio-3990X/ with commit f35b5d7d676e ("mm: align larger anonymous mappings on THP boundaries"). And the commit f35b5d7d676e was reverted. It turned out the regression is related with madvise(MADV_DONTNEED) was used by ld.lld. But with none PMD_SIZE aligned parameter len. trace-bpfcc captured: 531607 531732 ld.lld do_madvise.part.0 start: 0x7feca9000000, len: 0x7fb000, behavior: 0x4 531607 531793 ld.lld do_madvise.part.0 start: 0x7fec86a00000, len: 0x7fb000, behavior: 0x4 If the underneath physical page is THP, the madvise(MADV_DONTNEED) can trigger split_queue_lock contention raised significantly. perf showed following data: 14.85% 0.00% ld.lld [kernel.kallsyms] [k] entry_SYSCALL_64_after_hwframe 11.52% entry_SYSCALL_64_after_hwframe do_syscall_64 __x64_sys_madvise do_madvise.part.0 zap_page_range unmap_single_vma unmap_page_range page_remove_rmap deferred_split_huge_page __lock_text_start native_queued_spin_lock_slowpath If THP can't be removed from rmap as whole THP, partial THP will be removed from rmap by removing sub-pages from rmap. Even the THP head page is added to deferred queue already, the split_queue_lock will be acquired and check whether the THP head page is in the queue already. Thus, the contention of split_queue_lock is raised. Before acquire split_queue_lock, check and bail out early if the THP head page is in the queue already. The checking without holding split_queue_lock could race with deferred_split_scan, but it doesn't impact the correctness here. Test result of building kernel with ld.lld: commit 7b5a0b664ebe (parent commit of f35b5d7d676e): time -f "\t%E real,\t%U user,\t%S sys" make LD=ld.lld -skj96 allmodconfig all 6:07.99 real, 26367.77 user, 5063.35 sys commit f35b5d7d676e: time -f "\t%E real,\t%U user,\t%S sys" make LD=ld.lld -skj96 allmodconfig all 7:22.15 real, 26235.03 user, 12504.55 sys commit f35b5d7d676e with the fixing patch: time -f "\t%E real,\t%U user,\t%S sys" make LD=ld.lld -skj96 allmodconfig all 6:08.49 real, 26520.15 user, 5047.91 sys Link: https://lkml.kernel.org/r/20221223135207.2275317-1-fengwei.yin@intel.com Signed-off-by: Yin Fengwei <fengwei.yin@intel.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Feng Tang <feng.tang@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com> Cc: Yang Shi <shy828301@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
Johannes Weiner
|
24900f3596 |
mm: memcontrol: deprecate charge moving
commit da34a8484d162585e22ed8c1e4114aa2f60e3567 upstream. Charge moving mode in cgroup1 allows memory to follow tasks as they migrate between cgroups. This is, and always has been, a questionable thing to do - for several reasons. First, it's expensive. Pages need to be identified, locked and isolated from various MM operations, and reassigned, one by one. Second, it's unreliable. Once pages are charged to a cgroup, there isn't always a clear owner task anymore. Cache isn't moved at all, for example. Mapped memory is moved - but if trylocking or isolating a page fails, it's arbitrarily left behind. Frequent moving between domains may leave a task's memory scattered all over the place. Third, it isn't really needed. Launcher tasks can kick off workload tasks directly in their target cgroup. Using dedicated per-workload groups allows fine-grained policy adjustments - no need to move tasks and their physical pages between control domains. The feature was never forward-ported to cgroup2, and it hasn't been missed. Despite it being a niche usecase, the maintenance overhead of supporting it is enormous. Because pages are moved while they are live and subject to various MM operations, the synchronization rules are complicated. There are lock_page_memcg() in MM and FS code, which non-cgroup people don't understand. In some cases we've been able to shift code and cgroup API calls around such that we can rely on native locking as much as possible. But that's fragile, and sometimes we need to hold MM locks for longer than we otherwise would (pte lock e.g.). Mark the feature deprecated. Hopefully we can remove it soon. And backport into -stable kernels so that people who develop against earlier kernels are warned about this deprecation as early as possible. [akpm@linux-foundation.org: fix memory.rst underlining] Link: https://lkml.kernel.org/r/Y5COd+qXwk/S+n8N@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeelb@google.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
Aaron Thompson
|
6b08c9fc72 |
Revert "mm: Always release pages to the buddy allocator in memblock_free_late()."
commit 647037adcad00f2bab8828d3d41cd0553d41f3bd upstream.
This reverts commit 115d9d77bb0f9152c60b6e8646369fa7f6167593.
The pages being freed by memblock_free_late() have already been
initialized, but if they are in the deferred init range,
__free_one_page() might access nearby uninitialized pages when trying to
coalesce buddies. This can, for example, trigger this BUG:
BUG: unable to handle page fault for address: ffffe964c02580c8
RIP: 0010:__list_del_entry_valid+0x3f/0x70
<TASK>
__free_one_page+0x139/0x410
__free_pages_ok+0x21d/0x450
memblock_free_late+0x8c/0xb9
efi_free_boot_services+0x16b/0x25c
efi_enter_virtual_mode+0x403/0x446
start_kernel+0x678/0x714
secondary_startup_64_no_verify+0xd2/0xdb
</TASK>
A proper fix will be more involved so revert this change for the time
being.
Fixes: 115d9d77bb0f ("mm: Always release pages to the buddy allocator in memblock_free_late().")
Signed-off-by: Aaron Thompson <dev@aaront.org>
Link: https://lore.kernel.org/r/20230207082151.1303-1-dev@aaront.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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Mike Kravetz
|
a94695e0f9 |
migrate: hugetlb: check for hugetlb shared PMD in node migration
commit 73bdf65ea74857d7fb2ec3067a3cec0e261b1462 upstream.
migrate_pages/mempolicy semantics state that CAP_SYS_NICE is required to
move pages shared with another process to a different node. page_mapcount
> 1 is being used to determine if a hugetlb page is shared. However, a
hugetlb page will have a mapcount of 1 if mapped by multiple processes via
a shared PMD. As a result, hugetlb pages shared by multiple processes and
mapped with a shared PMD can be moved by a process without CAP_SYS_NICE.
To fix, check for a shared PMD if mapcount is 1. If a shared PMD is found
consider the page shared.
Link: https://lkml.kernel.org/r/20230126222721.222195-3-mike.kravetz@oracle.com
Fixes:
|
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Andrea Righi
|
5af2f74f90 |
mm: swap: properly update readahead statistics in unuse_pte_range()
commit ebc5951eea499314f6fbbde20e295f1345c67330 upstream.
In unuse_pte_range() we blindly swap-in pages without checking if the
swap entry is already present in the swap cache.
By doing this, the hit/miss ratio used by the swap readahead heuristic
is not properly updated and this leads to non-optimal performance during
swapoff.
Tracing the distribution of the readahead size returned by the swap
readahead heuristic during swapoff shows that a small readahead size is
used most of the time as if we had only misses (this happens both with
cluster and vma readahead), for example:
r::swapin_nr_pages(unsigned long offset):unsigned long:$retval
COUNT EVENT
36948 $retval = 8
44151 $retval = 4
49290 $retval = 1
527771 $retval = 2
Checking if the swap entry is present in the swap cache, instead, allows
to properly update the readahead statistics and the heuristic behaves in a
better way during swapoff, selecting a bigger readahead size:
r::swapin_nr_pages(unsigned long offset):unsigned long:$retval
COUNT EVENT
1618 $retval = 1
4960 $retval = 2
41315 $retval = 4
103521 $retval = 8
In terms of swapoff performance the result is the following:
Testing environment
===================
- Host:
CPU: 1.8GHz Intel Core i7-8565U (quad-core, 8MB cache)
HDD: PC401 NVMe SK hynix 512GB
MEM: 16GB
- Guest (kvm):
8GB of RAM
virtio block driver
16GB swap file on ext4 (/swapfile)
Test case
=========
- allocate 85% of memory
- `systemctl hibernate` to force all the pages to be swapped-out to the
swap file
- resume the system
- measure the time that swapoff takes to complete:
# /usr/bin/time swapoff /swapfile
Result (swapoff time)
======
5.6 vanilla 5.6 w/ this patch
----------- -----------------
cluster-readahead 22.09s 12.19s
vma-readahead 18.20s 15.33s
Conclusion
==========
The specific use case this patch is addressing is to improve swapoff
performance in cloud environments when a VM has been hibernated, resumed
and all the memory needs to be forced back to RAM by disabling swap.
This change allows to better exploits the advantages of the readahead
heuristic during swapoff and this improvement allows to to speed up the
resume process of such VMs.
[andrea.righi@canonical.com: update changelog]
Link: http://lkml.kernel.org/r/20200418084705.GA147642@xps-13
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Anchal Agarwal <anchalag@amazon.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Vineeth Remanan Pillai <vpillai@digitalocean.com>
Cc: Kelley Nielsen <kelleynnn@gmail.com>
Link: http://lkml.kernel.org/r/20200416180132.GB3352@xps-13
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luiz Capitulino <luizcap@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
Longlong Xia
|
d49c85a191 |
mm/swapfile: add cond_resched() in get_swap_pages()
commit 7717fc1a12f88701573f9ed897cc4f6699c661e3 upstream. The softlockup still occurs in get_swap_pages() under memory pressure. 64 CPU cores, 64GB memory, and 28 zram devices, the disksize of each zram device is 50MB with same priority as si. Use the stress-ng tool to increase memory pressure, causing the system to oom frequently. The plist_for_each_entry_safe() loops in get_swap_pages() could reach tens of thousands of times to find available space (extreme case: cond_resched() is not called in scan_swap_map_slots()). Let's add cond_resched() into get_swap_pages() when failed to find available space to avoid softlockup. Link: https://lkml.kernel.org/r/20230128094757.1060525-1-xialonglong1@huawei.com Signed-off-by: Longlong Xia <xialonglong1@huawei.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Chen Wandun <chenwandun@huawei.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Nanyong Sun <sunnanyong@huawei.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|
Kees Cook
|
51538bdde3 |
panic: Consolidate open-coded panic_on_warn checks
commit 79cc1ba7badf9e7a12af99695a557e9ce27ee967 upstream. Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll their own warnings, and each check "panic_on_warn". Consolidate this into a single function so that future instrumentation can be added in a single location. Cc: Marco Elver <elver@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Segall <bsegall@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Valentin Schneider <vschneid@redhat.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: David Gow <davidgow@google.com> Cc: tangmeng <tangmeng@uniontech.com> Cc: Jann Horn <jannh@google.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Petr Mladek <pmladek@suse.com> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com> Cc: Tiezhu Yang <yangtiezhu@loongson.cn> Cc: kasan-dev@googlegroups.com Cc: linux-mm@kvack.org Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Link: https://lore.kernel.org/r/20221117234328.594699-4-keescook@chromium.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
David Gow
|
2f87e25512 |
mm: kasan: do not panic if both panic_on_warn and kasan_multishot set
commit be4f1ae978ffe98cc95ec49ceb95386fb4474974 upstream. KASAN errors will currently trigger a panic when panic_on_warn is set. This renders kasan_multishot useless, as further KASAN errors won't be reported if the kernel has already paniced. By making kasan_multishot disable this behaviour for KASAN errors, we can still have the benefits of panic_on_warn for non-KASAN warnings, yet be able to use kasan_multishot. This is particularly important when running KASAN tests, which need to trigger multiple KASAN errors: previously these would panic the system if panic_on_warn was set, now they can run (and will panic the system should non-KASAN warnings show up). Signed-off-by: David Gow <davidgow@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Brendan Higgins <brendanhiggins@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Patricia Alfonso <trishalfonso@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Shuah Khan <shuah@kernel.org> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lkml.kernel.org/r/20200915035828.570483-6-davidgow@google.com Link: https://lkml.kernel.org/r/20200910070331.3358048-6-davidgow@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
|
Hugh Dickins
|
29487eed37 |
mm/khugepaged: fix collapse_pte_mapped_thp() to allow anon_vma
commit ab0c3f1251b4670978fde0bd54161795a139b060 upstream. uprobe_write_opcode() uses collapse_pte_mapped_thp() to restore huge pmd, when removing a breakpoint from hugepage text: vma->anon_vma is always set in that case, so undo the prohibition. And MADV_COLLAPSE ought to be able to collapse some page tables in a vma which happens to have anon_vma set from CoWing elsewhere. Is anon_vma lock required? Almost not: if any page other than expected subpage of the non-anon huge page is found in the page table, collapse is aborted without making any change. However, it is possible that an anon page was CoWed from this extent in another mm or vma, in which case a concurrent lookup might look here: so keep it away while clearing pmd (but perhaps we shall go back to using pmd_lock() there in future). Note that collapse_pte_mapped_thp() is exceptional in freeing a page table without having cleared its ptes: I'm uneasy about that, and had thought pte_clear()ing appropriate; but exclusive i_mmap lock does fix the problem, and we would have to move the mmu_notification if clearing those ptes. What this fixes is not a dangerous instability. But I suggest Cc stable because uprobes "healing" has regressed in that way, so this should follow 8d3c106e19e8 into those stable releases where it was backported (and may want adjustment there - I'll supply backports as needed). Link: https://lkml.kernel.org/r/b740c9fb-edba-92ba-59fb-7a5592e5dfc@google.com Fixes: 8d3c106e19e8 ("mm/khugepaged: take the right locks for page table retraction") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Zach O'Keefe <zokeefe@google.com> Cc: Song Liu <songliubraving@fb.com> Cc: <stable@vger.kernel.org> [5.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|
Aaron Thompson
|
ecd47ffc99 |
mm: Always release pages to the buddy allocator in memblock_free_late().
commit 115d9d77bb0f9152c60b6e8646369fa7f6167593 upstream.
If CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, memblock_free_pages()
only releases pages to the buddy allocator if they are not in the
deferred range. This is correct for free pages (as defined by
for_each_free_mem_pfn_range_in_zone()) because free pages in the
deferred range will be initialized and released as part of the deferred
init process. memblock_free_pages() is called by memblock_free_late(),
which is used to free reserved ranges after memblock_free_all() has
run. All pages in reserved ranges have been initialized at that point,
and accordingly, those pages are not touched by the deferred init
process. This means that currently, if the pages that
memblock_free_late() intends to release are in the deferred range, they
will never be released to the buddy allocator. They will forever be
reserved.
In addition, memblock_free_pages() calls kmsan_memblock_free_pages(),
which is also correct for free pages but is not correct for reserved
pages. KMSAN metadata for reserved pages is initialized by
kmsan_init_shadow(), which runs shortly before memblock_free_all().
For both of these reasons, memblock_free_pages() should only be called
for free pages, and memblock_free_late() should call __free_pages_core()
directly instead.
One case where this issue can occur in the wild is EFI boot on
x86_64. The x86 EFI code reserves all EFI boot services memory ranges
via memblock_reserve() and frees them later via memblock_free_late()
(efi_reserve_boot_services() and efi_free_boot_services(),
respectively). If any of those ranges happens to fall within the
deferred init range, the pages will not be released and that memory will
be unavailable.
For example, on an Amazon EC2 t3.micro VM (1 GB) booting via EFI:
v6.2-rc2:
# grep -E 'Node|spanned|present|managed' /proc/zoneinfo
Node 0, zone DMA
spanned 4095
present 3999
managed 3840
Node 0, zone DMA32
spanned 246652
present 245868
managed 178867
v6.2-rc2 + patch:
# grep -E 'Node|spanned|present|managed' /proc/zoneinfo
Node 0, zone DMA
spanned 4095
present 3999
managed 3840
Node 0, zone DMA32
spanned 246652
present 245868
managed 222816 # +43,949 pages
Fixes:
|
||
NARIBAYASHI Akira
|
f02d2e2b9b |
mm, compaction: fix fast_isolate_around() to stay within boundaries
commit be21b32afe470c5ae98e27e49201158a47032942 upstream.
Depending on the memory configuration, isolate_freepages_block() may scan
pages out of the target range and causes panic.
Panic can occur on systems with multiple zones in a single pageblock.
The reason it is rare is that it only happens in special
configurations. Depending on how many similar systems there are, it
may be a good idea to fix this problem for older kernels as well.
The problem is that pfn as argument of fast_isolate_around() could be out
of the target range. Therefore we should consider the case where pfn <
start_pfn, and also the case where end_pfn < pfn.
This problem should have been addressd by the commit 6e2b7044c199 ("mm,
compaction: make fast_isolate_freepages() stay within zone") but there was
an oversight.
Case1: pfn < start_pfn
<at memory compaction for node Y>
| node X's zone | node Y's zone
+-----------------+------------------------------...
pageblock ^ ^ ^
+-----------+-----------+-----------+-----------+...
^ ^ ^
^ ^ end_pfn
^ start_pfn = cc->zone->zone_start_pfn
pfn
<---------> scanned range by "Scan After"
Case2: end_pfn < pfn
<at memory compaction for node X>
| node X's zone | node Y's zone
+-----------------+------------------------------...
pageblock ^ ^ ^
+-----------+-----------+-----------+-----------+...
^ ^ ^
^ ^ pfn
^ end_pfn
start_pfn
<---------> scanned range by "Scan Before"
It seems that there is no good reason to skip nr_isolated pages just after
given pfn. So let perform simple scan from start to end instead of
dividing the scan into "Before" and "After".
Link: https://lkml.kernel.org/r/20221026112438.236336-1-a.naribayashi@fujitsu.com
Fixes: 6e2b7044c199 ("mm, compaction: make fast_isolate_freepages() stay within zone").
Signed-off-by: NARIBAYASHI Akira <a.naribayashi@fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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Baolin Wang
|
176ba4c19d |
mm/hugetlb: fix races when looking up a CONT-PTE/PMD size hugetlb page
commit fac35ba763ed07ba93154c95ffc0c4a55023707f upstream. On some architectures (like ARM64), it can support CONT-PTE/PMD size hugetlb, which means it can support not only PMD/PUD size hugetlb (2M and 1G), but also CONT-PTE/PMD size(64K and 32M) if a 4K page size specified. So when looking up a CONT-PTE size hugetlb page by follow_page(), it will use pte_offset_map_lock() to get the pte entry lock for the CONT-PTE size hugetlb in follow_page_pte(). However this pte entry lock is incorrect for the CONT-PTE size hugetlb, since we should use huge_pte_lock() to get the correct lock, which is mm->page_table_lock. That means the pte entry of the CONT-PTE size hugetlb under current pte lock is unstable in follow_page_pte(), we can continue to migrate or poison the pte entry of the CONT-PTE size hugetlb, which can cause some potential race issues, even though they are under the 'pte lock'. For example, suppose thread A is trying to look up a CONT-PTE size hugetlb page by move_pages() syscall under the lock, however antoher thread B can migrate the CONT-PTE hugetlb page at the same time, which will cause thread A to get an incorrect page, if thread A also wants to do page migration, then data inconsistency error occurs. Moreover we have the same issue for CONT-PMD size hugetlb in follow_huge_pmd(). To fix above issues, rename the follow_huge_pmd() as follow_huge_pmd_pte() to handle PMD and PTE level size hugetlb, which uses huge_pte_lock() to get the correct pte entry lock to make the pte entry stable. Mike said: Support for CONT_PMD/_PTE was added with |
||
John Starks
|
04edfa3dc0 |
mm/gup: fix gup_pud_range() for dax
commit fcd0ccd836ffad73d98a66f6fea7b16f735ea920 upstream. For dax pud, pud_huge() returns true on x86. So the function works as long as hugetlb is configured. However, dax doesn't depend on hugetlb. Commit |
||
Tejun Heo
|
35963b3182 |
memcg: fix possible use-after-free in memcg_write_event_control()
commit 4a7ba45b1a435e7097ca0f79a847d0949d0eb088 upstream. memcg_write_event_control() accesses the dentry->d_name of the specified control fd to route the write call. As a cgroup interface file can't be renamed, it's safe to access d_name as long as the specified file is a regular cgroup file. Also, as these cgroup interface files can't be removed before the directory, it's safe to access the parent too. Prior to |
||
Jann Horn
|
5ffc2a7553 |
mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths
commit f268f6cf875f3220afc77bdd0bf1bb136eb54db9 upstream. Any codepath that zaps page table entries must invoke MMU notifiers to ensure that secondary MMUs (like KVM) don't keep accessing pages which aren't mapped anymore. Secondary MMUs don't hold their own references to pages that are mirrored over, so failing to notify them can lead to page use-after-free. I'm marking this as addressing an issue introduced in commit |
||
|
Jann Horn
|
48b00ceb54 |
mm/khugepaged: fix GUP-fast interaction by sending IPI
commit 2ba99c5e08812494bc57f319fb562f527d9bacd8 upstream.
Since commit 70cbc3cc78a99 ("mm: gup: fix the fast GUP race against THP
collapse"), the lockless_pages_from_mm() fastpath rechecks the pmd_t to
ensure that the page table was not removed by khugepaged in between.
However, lockless_pages_from_mm() still requires that the page table is
not concurrently freed. Fix it by sending IPIs (if the architecture uses
semi-RCU-style page table freeing) before freeing/reusing page tables.
Link: https://lkml.kernel.org/r/20221129154730.2274278-2-jannh@google.com
Link: https://lkml.kernel.org/r/20221128180252.1684965-2-jannh@google.com
Link: https://lkml.kernel.org/r/20221125213714.4115729-2-jannh@google.com
Fixes:
|
||
|
Jann Horn
|
324abbd8b9 |
mm/khugepaged: take the right locks for page table retraction
commit 8d3c106e19e8d251da31ff4cc7462e4565d65084 upstream.
pagetable walks on address ranges mapped by VMAs can be done under the
mmap lock, the lock of an anon_vma attached to the VMA, or the lock of the
VMA's address_space. Only one of these needs to be held, and it does not
need to be held in exclusive mode.
Under those circumstances, the rules for concurrent access to page table
entries are:
- Terminal page table entries (entries that don't point to another page
table) can be arbitrarily changed under the page table lock, with the
exception that they always need to be consistent for
hardware page table walks and lockless_pages_from_mm().
This includes that they can be changed into non-terminal entries.
- Non-terminal page table entries (which point to another page table)
can not be modified; readers are allowed to READ_ONCE() an entry, verify
that it is non-terminal, and then assume that its value will stay as-is.
Retracting a page table involves modifying a non-terminal entry, so
page-table-level locks are insufficient to protect against concurrent page
table traversal; it requires taking all the higher-level locks under which
it is possible to start a page walk in the relevant range in exclusive
mode.
The collapse_huge_page() path for anonymous THP already follows this rule,
but the shmem/file THP path was getting it wrong, making it possible for
concurrent rmap-based operations to cause corruption.
Link: https://lkml.kernel.org/r/20221129154730.2274278-1-jannh@google.com
Link: https://lkml.kernel.org/r/20221128180252.1684965-1-jannh@google.com
Link: https://lkml.kernel.org/r/20221125213714.4115729-1-jannh@google.com
Fixes:
|
||
|
Linus Torvalds
|
210f96fb7e |
v4l2: don't fall back to follow_pfn() if pin_user_pages_fast() fails
commit 6647e76ab623b2b3fb2efe03a86e9c9046c52c33 upstream.
The V4L2_MEMORY_USERPTR interface is long deprecated and shouldn't be
used (and is discouraged for any modern v4l drivers). And Seth Jenkins
points out that the fallback to VM_PFNMAP/VM_IO is fundamentally racy
and dangerous.
Note that it's not even a case that should trigger, since any normal
user pointer logic ends up just using the pin_user_pages_fast() call
that does the proper page reference counting. That's not the problem
case, only if you try to use special device mappings do you have any
issues.
Normally I'd just remove this during the merge window, but since Seth
pointed out the problem cases, we really want to know as soon as
possible if there are actually any users of this odd special case of a
legacy interface. Neither Hans nor Mauro seem to think that such
mis-uses of the old legacy interface should exist. As Mauro says:
"See, V4L2 has actually 4 streaming APIs:
- Kernel-allocated mmap (usually referred simply as just mmap);
- USERPTR mmap;
- read();
- dmabuf;
The USERPTR is one of the oldest way to use it, coming from V4L
version 1 times, and by far the least used one"
And Hans chimed in on the USERPTR interface:
"To be honest, I wouldn't mind if it goes away completely, but that's a
bit of a pipe dream right now"
but while removing this legacy interface entirely may be a pipe dream we
can at least try to remove the unlikely (and actively broken) case of
using special device mappings for USERPTR accesses.
This replaces it with a WARN_ONCE() that we can remove once we've
hopefully confirmed that no actual users exist.
NOTE! Longer term, this means that a 'struct frame_vector' only ever
contains proper page pointers, and all the games we have with converting
them to pages can go away (grep for 'frame_vector_to_pages()' and the
uses of 'vec->is_pfns'). But this is just the first step, to verify
that this code really is all dead, and do so as quickly as possible.
Reported-by: Seth Jenkins <sethjenkins@google.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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Alexander Potapenko
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ed8b990e89 |
mm: fs: initialize fsdata passed to write_begin/write_end interface
commit 1468c6f4558b1bcd92aa0400f2920f9dc7588402 upstream. Functions implementing the a_ops->write_end() interface accept the `void *fsdata` parameter that is supposed to be initialized by the corresponding a_ops->write_begin() (which accepts `void **fsdata`). However not all a_ops->write_begin() implementations initialize `fsdata` unconditionally, so it may get passed uninitialized to a_ops->write_end(), resulting in undefined behavior. Fix this by initializing fsdata with NULL before the call to write_begin(), rather than doing so in all possible a_ops implementations. This patch covers only the following cases found by running x86 KMSAN under syzkaller: - generic_perform_write() - cont_expand_zero() and generic_cont_expand_simple() - page_symlink() Other cases of passing uninitialized fsdata may persist in the codebase. Link: https://lkml.kernel.org/r/20220915150417.722975-43-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Marco Elver <elver@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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Rik van Riel
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11993652d0 |
mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages
commit 12df140f0bdfae5dcfc81800970dd7f6f632e00c upstream.
The h->*_huge_pages counters are protected by the hugetlb_lock, but
alloc_huge_page has a corner case where it can decrement the counter
outside of the lock.
This could lead to a corrupted value of h->resv_huge_pages, which we have
observed on our systems.
Take the hugetlb_lock before decrementing h->resv_huge_pages to avoid a
potential race.
Link: https://lkml.kernel.org/r/20221017202505.0e6a4fcd@imladris.surriel.com
Fixes:
|
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Steven Price
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393a1aa421 |
mm: pagewalk: Fix race between unmap and page walker
commit 8782fb61cc848364e1e1599d76d3c9dd58a1cc06 upstream.
The mmap lock protects the page walker from changes to the page tables
during the walk. However a read lock is insufficient to protect those
areas which don't have a VMA as munmap() detaches the VMAs before
downgrading to a read lock and actually tearing down PTEs/page tables.
For users of walk_page_range() the solution is to simply call pte_hole()
immediately without checking the actual page tables when a VMA is not
present. We now never call __walk_page_range() without a valid vma.
For walk_page_range_novma() the locking requirements are tightened to
require the mmap write lock to be taken, and then walking the pgd
directly with 'no_vma' set.
This in turn means that all page walkers either have a valid vma, or
it's that special 'novma' case for page table debugging. As a result,
all the odd '(!walk->vma && !walk->no_vma)' tests can be removed.
Fixes:
|
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Minchan Kim
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0f4634f70b |
mm: fix madivse_pageout mishandling on non-LRU page
commit 58d426a7ba92870d489686dfdb9d06b66815a2ab upstream.
MADV_PAGEOUT tries to isolate non-LRU pages and gets a warning from
isolate_lru_page below.
Fix it by checking PageLRU in advance.
------------[ cut here ]------------
trying to isolate tail page
WARNING: CPU: 0 PID: 6175 at mm/folio-compat.c:158 isolate_lru_page+0x130/0x140
Modules linked in:
CPU: 0 PID: 6175 Comm: syz-executor.0 Not tainted 5.18.12 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:isolate_lru_page+0x130/0x140
Link: https://lore.kernel.org/linux-mm/485f8c33.2471b.182d5726afb.Coremail.hantianshuo@iie.ac.cn/
Link: https://lkml.kernel.org/r/20220908151204.762596-1-minchan@kernel.org
Fixes:
|
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Alistair Popple
|
ffd11370b7 |
mm/migrate_device.c: flush TLB while holding PTL
commit 60bae73708963de4a17231077285bd9ff2f41c44 upstream.
When clearing a PTE the TLB should be flushed whilst still holding the PTL
to avoid a potential race with madvise/munmap/etc. For example consider
the following sequence:
CPU0 CPU1
---- ----
migrate_vma_collect_pmd()
pte_unmap_unlock()
madvise(MADV_DONTNEED)
-> zap_pte_range()
pte_offset_map_lock()
[ PTE not present, TLB not flushed ]
pte_unmap_unlock()
[ page is still accessible via stale TLB ]
flush_tlb_range()
In this case the page may still be accessed via the stale TLB entry after
madvise returns. Fix this by flushing the TLB while holding the PTL.
Fixes:
|
||
Maurizio Lombardi
|
b9e31f4885 |
mm: prevent page_frag_alloc() from corrupting the memory
commit dac22531bbd4af2426c4e29e05594415ccfa365d upstream.
A number of drivers call page_frag_alloc() with a fragment's size >
PAGE_SIZE.
In low memory conditions, __page_frag_cache_refill() may fail the order
3 cache allocation and fall back to order 0; In this case, the cache
will be smaller than the fragment, causing memory corruptions.
Prevent this from happening by checking if the newly allocated cache is
large enough for the fragment; if not, the allocation will fail and
page_frag_alloc() will return NULL.
Link: https://lkml.kernel.org/r/20220715125013.247085-1-mlombard@redhat.com
Fixes:
|
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Mel Gorman
|
d535fb8384 |
mm/page_alloc: fix race condition between build_all_zonelists and page allocation
commit 3d36424b3b5850bd92f3e89b953a430d7cfc88ef upstream. Patrick Daly reported the following problem; NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK] - before offline operation [0] - ZONE_MOVABLE [1] - ZONE_NORMAL [2] - NULL For a GFP_KERNEL allocation, alloc_pages_slowpath() will save the offset of ZONE_NORMAL in ac->preferred_zoneref. If a concurrent memory_offline operation removes the last page from ZONE_MOVABLE, build_all_zonelists() & build_zonerefs_node() will update node_zonelists as shown below. Only populated zones are added. NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK] - after offline operation [0] - ZONE_NORMAL [1] - NULL [2] - NULL The race is simple -- page allocation could be in progress when a memory hot-remove operation triggers a zonelist rebuild that removes zones. The allocation request will still have a valid ac->preferred_zoneref that is now pointing to NULL and triggers an OOM kill. This problem probably always existed but may be slightly easier to trigger due to |
||
Chao Yu
|
016b150992 |
mm/slub: fix to return errno if kmalloc() fails
commit 7e9c323c52b379d261a72dc7bd38120a761a93cd upstream.
In create_unique_id(), kmalloc(, GFP_KERNEL) can fail due to
out-of-memory, if it fails, return errno correctly rather than
triggering panic via BUG_ON();
kernel BUG at mm/slub.c:5893!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Call trace:
sysfs_slab_add+0x258/0x260 mm/slub.c:5973
__kmem_cache_create+0x60/0x118 mm/slub.c:4899
create_cache mm/slab_common.c:229 [inline]
kmem_cache_create_usercopy+0x19c/0x31c mm/slab_common.c:335
kmem_cache_create+0x1c/0x28 mm/slab_common.c:390
f2fs_kmem_cache_create fs/f2fs/f2fs.h:2766 [inline]
f2fs_init_xattr_caches+0x78/0xb4 fs/f2fs/xattr.c:808
f2fs_fill_super+0x1050/0x1e0c fs/f2fs/super.c:4149
mount_bdev+0x1b8/0x210 fs/super.c:1400
f2fs_mount+0x44/0x58 fs/f2fs/super.c:4512
legacy_get_tree+0x30/0x74 fs/fs_context.c:610
vfs_get_tree+0x40/0x140 fs/super.c:1530
do_new_mount+0x1dc/0x4e4 fs/namespace.c:3040
path_mount+0x358/0x914 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x2f8/0x408 fs/namespace.c:3568
Cc: <stable@kernel.org>
Fixes:
|
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Jann Horn
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c128bff9ff |
mm: Fix TLB flush for not-first PFNMAP mappings in unmap_region()
This is a stable-specific patch.
I botched the stable-specific rewrite of
commit b67fbebd4cf98 ("mmu_gather: Force tlb-flush VM_PFNMAP vmas"):
As Hugh pointed out, unmap_region() actually operates on a list of VMAs,
and the variable "vma" merely points to the first VMA in that list.
So if we want to check whether any of the VMAs we're operating on is
PFNMAP or MIXEDMAP, we have to iterate through the list and check each VMA.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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Yee Lee
|
007541bc27 |
Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()"
This reverts commit 23c2d497de21f25898fbea70aeb292ab8acc8c94.
Commit 23c2d497de21 ("mm: kmemleak: take a full lowmem check in
kmemleak_*_phys()") brought false leak alarms on some archs like arm64
that does not init pfn boundary in early booting. The final solution
lands on linux-6.0: commit 0c24e061196c ("mm: kmemleak: add rbtree and
store physical address for objects allocated with PA").
Revert this commit before linux-6.0. The original issue of invalid PA
can be mitigated by additional check in devicetree.
The false alarm report is as following: Kmemleak output: (Qemu/arm64)
unreferenced object 0xffff0000c0170a00 (size 128):
comm "swapper/0", pid 1, jiffies 4294892404 (age 126.208s)
hex dump (first 32 bytes):
62 61 73 65 00 00 00 00 00 00 00 00 00 00 00 00 base............
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<(____ptrval____)>] __kmalloc_track_caller+0x1b0/0x2e4
[<(____ptrval____)>] kstrdup_const+0x8c/0xc4
[<(____ptrval____)>] kvasprintf_const+0xbc/0xec
[<(____ptrval____)>] kobject_set_name_vargs+0x58/0xe4
[<(____ptrval____)>] kobject_add+0x84/0x100
[<(____ptrval____)>] __of_attach_node_sysfs+0x78/0xec
[<(____ptrval____)>] of_core_init+0x68/0x104
[<(____ptrval____)>] driver_init+0x28/0x48
[<(____ptrval____)>] do_basic_setup+0x14/0x28
[<(____ptrval____)>] kernel_init_freeable+0x110/0x178
[<(____ptrval____)>] kernel_init+0x20/0x1a0
[<(____ptrval____)>] ret_from_fork+0x10/0x20
This pacth is also applicable to linux-5.17.y/linux-5.18.y/linux-5.19.y
Cc: <stable@vger.kernel.org>
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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|
Jann Horn
|
2fe3eee488 |
mm/rmap: Fix anon_vma->degree ambiguity leading to double-reuse
commit 2555283eb40df89945557273121e9393ef9b542b upstream.
anon_vma->degree tracks the combined number of child anon_vmas and VMAs
that use the anon_vma as their ->anon_vma.
anon_vma_clone() then assumes that for any anon_vma attached to
src->anon_vma_chain other than src->anon_vma, it is impossible for it to
be a leaf node of the VMA tree, meaning that for such VMAs ->degree is
elevated by 1 because of a child anon_vma, meaning that if ->degree
equals 1 there are no VMAs that use the anon_vma as their ->anon_vma.
This assumption is wrong because the ->degree optimization leads to leaf
nodes being abandoned on anon_vma_clone() - an existing anon_vma is
reused and no new parent-child relationship is created. So it is
possible to reuse an anon_vma for one VMA while it is still tied to
another VMA.
This is an issue because is_mergeable_anon_vma() and its callers assume
that if two VMAs have the same ->anon_vma, the list of anon_vmas
attached to the VMAs is guaranteed to be the same. When this assumption
is violated, vma_merge() can merge pages into a VMA that is not attached
to the corresponding anon_vma, leading to dangling page->mapping
pointers that will be dereferenced during rmap walks.
Fix it by separately tracking the number of child anon_vmas and the
number of VMAs using the anon_vma as their ->anon_vma.
Fixes:
|