KCSAN: data-race in __delete_from_page_cache / shmem_getpage_gfp

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c9c9e6a4 Merge tag 'trace-v5.9-rc5-2' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c8b9c5900000
kernel config: https://syzkaller.appspot.com/x/.config?x=7b00edac59eadd4a
dashboard link: https://syzkaller.appspot.com/bug?extid=4ab6a7ba6ca59b59a36f
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4ab6a7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __delete_from_page_cache / shmem_getpage_gfp

write to 0xffff88809eaa5dc8 of 8 bytes by task 10258 on cpu 0:
page_cache_delete mm/filemap.c:154 [inline]
__delete_from_page_cache+0x282/0x380 mm/filemap.c:239
__remove_mapping+0x3e2/0x490 mm/vmscan.c:928
shrink_page_list+0x139d/0x23c0 mm/vmscan.c:1431
reclaim_pages+0x40e/0x540 mm/vmscan.c:2143
madvise_cold_or_pageout_pte_range+0x13e5/0x1670 include/linux/spinlock.h:394
walk_pmd_range mm/pagewalk.c:89 [inline]
walk_pud_range mm/pagewalk.c:160 [inline]
walk_p4d_range mm/pagewalk.c:193 [inline]
walk_pgd_range mm/pagewalk.c:229 [inline]
__walk_page_range+0xa66/0x15a0 mm/pagewalk.c:331
walk_page_range+0x111/0x2e0 mm/pagewalk.c:427
madvise_pageout_page_range mm/madvise.c:521 [inline]
madvise_pageout mm/madvise.c:557 [inline]
madvise_vma mm/madvise.c:946 [inline]
do_madvise+0xc6e/0x14f0 mm/madvise.c:1145
__do_sys_madvise mm/madvise.c:1171 [inline]
__se_sys_madvise mm/madvise.c:1169 [inline]
__x64_sys_madvise+0x3e/0x50 mm/madvise.c:1169
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88809eaa5dc8 of 8 bytes by task 10247 on cpu 1:
shmem_recalc_inode mm/shmem.c:367 [inline]
shmem_getpage_gfp+0xb7c/0x19c0 mm/shmem.c:1930
shmem_fault+0x16c/0x430 mm/shmem.c:2107
__do_fault mm/memory.c:3462 [inline]
do_read_fault+0x41f/0x760 mm/memory.c:3855
do_fault mm/memory.c:3983 [inline]
handle_pte_fault mm/memory.c:4223 [inline]
__handle_mm_fault mm/memory.c:4358 [inline]
handle_mm_fault+0x14e9/0x1af0 mm/memory.c:4456
faultin_page mm/gup.c:878 [inline]
__get_user_pages+0xa3d/0x1010 mm/gup.c:1090
populate_vma_page_range mm/gup.c:1420 [inline]
__mm_populate+0x24d/0x340 mm/gup.c:1468
mm_populate include/linux/mm.h:2566 [inline]
vm_mmap_pgoff+0x133/0x170 mm/util.c:511
ksys_mmap_pgoff+0xe1/0x380 mm/mmap.c:1596
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10247 Comm: syz-executor.5 Not tainted 5.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.