KCSAN: data-race in filemap_fault / filemap_fault (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 495023e4 of: Drop superfluous ULL suffix for ~0
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11bf2c3a500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=8a8c9efba3b8cfd16488
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+8a8c9e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in filemap_fault / filemap_fault

write to 0xffff88810aac2498 of 8 bytes by task 8468 on cpu 0:
do_sync_mmap_readahead mm/filemap.c:2631 [inline]
filemap_fault+0x66a/0x12e0 mm/filemap.c:2723
ext4_filemap_fault+0x4b/0x60 fs/ext4/inode.c:6191
__do_fault mm/memory.c:3612 [inline]
do_read_fault+0x403/0x760 mm/memory.c:4006
do_fault mm/memory.c:4134 [inline]
handle_pte_fault mm/memory.c:4374 [inline]
__handle_mm_fault mm/memory.c:4509 [inline]
handle_mm_fault+0xfeb/0x1770 mm/memory.c:4607
do_user_addr_fault+0x33e/0x730 arch/x86/mm/fault.c:1372
handle_page_fault arch/x86/mm/fault.c:1429 [inline]
exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1485
asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:583

write to 0xffff88810aac2498 of 8 bytes by task 8461 on cpu 1:
do_sync_mmap_readahead mm/filemap.c:2631 [inline]
filemap_fault+0x66a/0x12e0 mm/filemap.c:2723
ext4_filemap_fault+0x4b/0x60 fs/ext4/inode.c:6191
__do_fault mm/memory.c:3612 [inline]
do_read_fault+0x403/0x760 mm/memory.c:4006
do_fault mm/memory.c:4134 [inline]
handle_pte_fault mm/memory.c:4374 [inline]
__handle_mm_fault mm/memory.c:4509 [inline]
handle_mm_fault+0xfeb/0x1770 mm/memory.c:4607
do_user_addr_fault+0x33e/0x730 arch/x86/mm/fault.c:1372
handle_page_fault arch/x86/mm/fault.c:1429 [inline]
exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1485
asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:583

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8461 Comm: syz-fuzzer Not tainted 5.10.0-rc2-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.