KCSAN: data-race in mm_update_next_owner / page_cache_ra_unbounded (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 23d72926 Merge tag 'for-linus-5.13b-rc3-tag' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12624a35d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=1f377806f2e72871
dashboard link: https://syzkaller.appspot.com/bug?extid=b77502a7c4de4cd1ed4e
compiler: Debian clang version 11.0.1-2
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+b77502...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in mm_update_next_owner / page_cache_ra_unbounded

write to 0xffff88813b3280ac of 4 bytes by task 20659 on cpu 0:
memalloc_nofs_save include/linux/sched/mm.h:249 [inline]
page_cache_ra_unbounded+0xa8/0x410 mm/readahead.c:193
do_page_cache_ra mm/readahead.c:267 [inline]
force_page_cache_ra+0x246/0x280 mm/readahead.c:299
page_cache_sync_ra+0xcc/0xe0 mm/readahead.c:573
page_cache_sync_readahead include/linux/pagemap.h:879 [inline]
filemap_get_pages mm/filemap.c:2467 [inline]
filemap_read+0x388/0x1230 mm/filemap.c:2550
generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2701
blkdev_read_iter+0xb9/0xf0 fs/block_dev.c:1732
call_read_iter include/linux/fs.h:2108 [inline]
new_sync_read fs/read_write.c:415 [inline]
vfs_read+0x565/0x5d0 fs/read_write.c:496
ksys_read+0xce/0x180 fs/read_write.c:634
__do_sys_read fs/read_write.c:644 [inline]
__se_sys_read fs/read_write.c:642 [inline]
__x64_sys_read+0x3e/0x50 fs/read_write.c:642
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813b3280ac of 4 bytes by task 20699 on cpu 1:
mm_update_next_owner+0x1d9/0x520 kernel/exit.c:389
exit_mm+0x358/0x450 kernel/exit.c:501
do_exit+0x3ff/0x1560 kernel/exit.c:813
do_group_exit+0x19b/0x1a0 kernel/exit.c:923
__do_sys_exit_group+0xb/0x10 kernel/exit.c:934
__se_sys_exit_group+0x5/0x10 kernel/exit.c:932
__x64_sys_exit_group+0x16/0x20 kernel/exit.c:932
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20699 Comm: syz-executor.1 Tainted: G W 5.13.0-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.