[moderation] [fs?] KCSAN: data-race in file_update_time / inode_set_ctime_to_ts

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 231825b2e1ff Revert "unicode: Don't special case ignorable..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11dcebe8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1fe4854f351e948c
dashboard link: https://syzkaller.appspot.com/bug?extid=8c4fe0d0a776bb62ee22
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2b0803efda5c/disk-231825b2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/82759e606254/vmlinux-231825b2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/42a011fdee37/bzImage-231825b2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8c4fe0...@syzkaller.appspotmail.com

BUG: KCSAN: data-race in file_update_time / inode_set_ctime_to_ts

read to 0xffff8881061c27b0 of 4 bytes by task 7641 on cpu 0:
inode_get_ctime_nsec include/linux/fs.h:1678 [inline]
inode_get_ctime include/linux/fs.h:1684 [inline]
inode_needs_update_time fs/inode.c:2336 [inline]
file_update_time+0xeb/0x2b0 fs/inode.c:2379
pipe_write+0xa7b/0xd20 fs/pipe.c:607
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x77f/0x920 fs/read_write.c:679
ksys_write+0xe8/0x1b0 fs/read_write.c:731
__do_sys_write fs/read_write.c:742 [inline]
__se_sys_write fs/read_write.c:739 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:739
x64_sys_call+0x287e/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881061c27b0 of 4 bytes by task 7638 on cpu 1:
inode_set_ctime_to_ts+0x85/0x180 fs/inode.c:2716
inode_set_ctime_current+0x1b7/0x7a0 fs/inode.c:2779
inode_update_timestamps+0x85/0x250 fs/inode.c:2066
generic_update_time fs/inode.c:2105 [inline]
inode_update_time fs/inode.c:2125 [inline]
__file_update_time fs/inode.c:2353 [inline]
file_update_time+0x219/0x2b0 fs/inode.c:2383
pipe_write+0xa7b/0xd20 fs/pipe.c:607
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x77f/0x920 fs/read_write.c:679
ksys_write+0xe8/0x1b0 fs/read_write.c:731
__do_sys_write fs/read_write.c:742 [inline]
__se_sys_write fs/read_write.c:739 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:739
x64_sys_call+0x287e/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x260a5345 -> 0x2dc9f7c8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7638 Comm: syz.1.1661 Not tainted 6.13.0-rc2-syzkaller-00036-g231825b2e1ff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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