[moderation] [fs?] KCSAN: data-race in inode_update_timestamps / inode_update_timestamps (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 347e9f5043c8 Linux 6.16-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14a2b0f0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c8b73fe883c5b6ae
dashboard link: https://syzkaller.appspot.com/bug?extid=1778e7de757c7b8ee0f5
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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/a4ea7737851a/disk-347e9f50.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7cbee5f5a70/vmlinux-347e9f50.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8cda2d02a95e/bzImage-347e9f50.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1778e7...@syzkaller.appspotmail.com

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

write to 0xffff888119b349ac of 4 bytes by task 861 on cpu 0:
inode_set_mtime_to_ts include/linux/fs.h:1718 [inline]
inode_update_timestamps+0x147/0x270 fs/inode.c:2022
generic_update_time fs/inode.c:2057 [inline]
inode_update_time fs/inode.c:2077 [inline]
__file_update_time fs/inode.c:2305 [inline]
file_update_time+0x20e/0x2b0 fs/inode.c:2335
fault_dirty_shared_page+0xd9/0x3c0 mm/memory.c:3420
do_shared_fault mm/memory.c:5682 [inline]
do_fault mm/memory.c:5728 [inline]
do_pte_missing mm/memory.c:4251 [inline]
handle_pte_fault mm/memory.c:6069 [inline]
__handle_mm_fault mm/memory.c:6212 [inline]
handle_mm_fault+0x165d/0x2be0 mm/memory.c:6381
do_user_addr_fault+0x636/0x1090 arch/x86/mm/fault.c:1336
handle_page_fault arch/x86/mm/fault.c:1476 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

read to 0xffff888119b349ac of 4 bytes by task 862 on cpu 1:
inode_get_mtime_nsec include/linux/fs.h:1704 [inline]
inode_get_mtime include/linux/fs.h:1710 [inline]
inode_update_timestamps+0x74/0x270 fs/inode.c:2016
generic_update_time fs/inode.c:2057 [inline]
inode_update_time fs/inode.c:2077 [inline]
__file_update_time fs/inode.c:2305 [inline]
file_update_time+0x20e/0x2b0 fs/inode.c:2335
fault_dirty_shared_page+0xd9/0x3c0 mm/memory.c:3420
do_shared_fault mm/memory.c:5682 [inline]
do_fault mm/memory.c:5728 [inline]
do_pte_missing mm/memory.c:4251 [inline]
handle_pte_fault mm/memory.c:6069 [inline]
__handle_mm_fault mm/memory.c:6212 [inline]
handle_mm_fault+0x165d/0x2be0 mm/memory.c:6381
faultin_page mm/gup.c:1186 [inline]
__get_user_pages+0x1036/0x1fb0 mm/gup.c:1488
__get_user_pages_locked mm/gup.c:1754 [inline]
faultin_page_range+0x10f/0x5b0 mm/gup.c:1978
madvise_populate mm/madvise.c:974 [inline]
madvise_do_behavior+0x120/0x1f20 mm/madvise.c:1731
do_madvise+0x103/0x190 mm/madvise.c:1826
__do_sys_madvise mm/madvise.c:1835 [inline]
__se_sys_madvise mm/madvise.c:1833 [inline]
__x64_sys_madvise+0x64/0x80 mm/madvise.c:1833
x64_sys_call+0x2455/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:29
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x1c03a8b0 -> 0x1c9c3f30

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 862 Comm: syz.7.10780 Not tainted 6.16.0-rc6-syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

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