KCSAN: data-race in mlock_fixup / try_to_unmap_one

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9e6a39ea Merge tag 'devicetree-fixes-for-5.10-2' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1799e726500000
kernel config: https://syzkaller.appspot.com/x/.config?x=671e27f23e60a67b
dashboard link: https://syzkaller.appspot.com/bug?extid=dad5f9bc93610bf74a13
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
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+dad5f9...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in mlock_fixup / try_to_unmap_one

write to 0xffff88810b7c55c8 of 8 bytes by task 29773 on cpu 0:
mlock_fixup+0x2a2/0x390 mm/mlock.c:579
apply_mlockall_flags+0x1cd/0x220 mm/mlock.c:797
__do_sys_mlockall mm/mlock.c:825 [inline]
__se_sys_mlockall+0x187/0x250 mm/mlock.c:804
__x64_sys_mlockall+0x1b/0x20 mm/mlock.c:804
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810b7c55c8 of 8 bytes by task 29761 on cpu 1:
try_to_unmap_one+0xb2/0x1720 mm/rmap.c:1389
rmap_walk_file+0x260/0x4f0 mm/rmap.c:1933
rmap_walk mm/rmap.c:1951 [inline]
try_to_munlock+0xe7/0x150 mm/rmap.c:1802
__munlock_isolated_page mm/mlock.c:141 [inline]
__munlock_pagevec+0x57d/0x830 mm/mlock.c:351
munlock_vma_pages_range+0x581/0x760 mm/mlock.c:504
munlock_vma_pages_all mm/internal.h:342 [inline]
exit_mmap+0x128/0x3b0 mm/mmap.c:3206
__mmput+0xa2/0x220 kernel/fork.c:1079
mmput+0x38/0x40 kernel/fork.c:1100
exit_mm+0x307/0x370 kernel/exit.c:486
do_exit+0x3c2/0x15a0 kernel/exit.c:796
do_group_exit+0x16f/0x170 kernel/exit.c:906
__do_sys_exit_group+0xb/0x10 kernel/exit.c:917
__se_sys_exit_group+0x5/0x10 kernel/exit.c:915
__x64_sys_exit_group+0x16/0x20 kernel/exit.c:915
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: 29761 Comm: syz-executor.5 Not tainted 5.10.0-rc3-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.