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| Filename | Latest commit message | Latest commit date |
|---|---|---|
74095bbbb1
[ Upstream commit 1bd6406fb5f36c2bb1e96e27d4c3e9f4d09edde4 ]
During our test, it is found that a warning can be trigger in try_grab_folio
as follow:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1678 at mm/gup.c:147 try_grab_folio+0x106/0x130
Modules linked in:
CPU: 0 UID: 0 PID: 1678 Comm: syz.3.31 Not tainted 6.15.0-rc5 #163 PREEMPT(undef)
RIP: 0010:try_grab_folio+0x106/0x130
Call Trace:
<TASK>
follow_huge_pmd+0x240/0x8e0
follow_pmd_mask.constprop.0.isra.0+0x40b/0x5c0
follow_pud_mask.constprop.0.isra.0+0x14a/0x170
follow_page_mask+0x1c2/0x1f0
__get_user_pages+0x176/0x950
__gup_longterm_locked+0x15b/0x1060
? gup_fast+0x120/0x1f0
gup_fast_fallback+0x17e/0x230
get_user_pages_fast+0x5f/0x80
vmci_host_unlocked_ioctl+0x21c/0xf80
RIP: 0033:0x54d2cd
---[ end trace 0000000000000000 ]---
Digging into the source, context->notify_page may init by get_user_pages_fast
and can be seen in vmci_ctx_unset_notify which will try to put_page. However
get_user_pages_fast is not finished here and lead to following
try_grab_folio warning. The race condition is shown as follow:
cpu0 cpu1
vmci_host_do_set_notify
vmci_host_setup_notify
get_user_pages_fast(uva, 1, FOLL_WRITE, &context->notify_page);
lockless_pages_from_mm
gup_pgd_range
gup_huge_pmd // update &context->notify_page
vmci_host_do_set_notify
vmci_ctx_unset_notify
notify_page = context->notify_page;
if (notify_page)
put_page(notify_page); // page is freed
__gup_longterm_locked
__get_user_pages
follow_trans_huge_pmd
try_grab_folio // warn here
To slove this, use local variable page to make notify_page can be seen
after finish get_user_pages_fast.
Fixes:
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.