[moderation] [fs?] KCSAN: data-race in inode_set_ctime_current / inode_update_timestamps (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 083fc6d7fa0d Merge tag 'sched-urgent-2025-09-26' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10933d34580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c7f65ba98bb01573
dashboard link: https://syzkaller.appspot.com/bug?extid=6c29d4079e33b2dfe612
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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/c167ba38cbbe/disk-083fc6d7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fd604c516d96/vmlinux-083fc6d7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dcbbcb23e97f/bzImage-083fc6d7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6c29d4...@syzkaller.appspotmail.com

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

write to 0xffff8881047289a0 of 8 bytes by task 8196 on cpu 0:
inode_set_ctime_current+0x533/0x770 fs/inode.c:2762
inode_update_timestamps+0x84/0x270 fs/inode.c:2017
generic_update_time fs/inode.c:2056 [inline]
inode_update_time fs/inode.c:2076 [inline]
__file_update_time fs/inode.c:2304 [inline]
file_update_time+0x20e/0x2b0 fs/inode.c:2334
fault_dirty_shared_page+0xd9/0x3c0 mm/memory.c:3403
do_shared_fault mm/memory.c:5665 [inline]
do_fault mm/memory.c:5711 [inline]
do_pte_missing mm/memory.c:4234 [inline]
handle_pte_fault mm/memory.c:6052 [inline]
__handle_mm_fault mm/memory.c:6195 [inline]
handle_mm_fault+0x165d/0x2c20 mm/memory.c:6364
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 0xffff8881047289a0 of 8 bytes by task 8203 on cpu 1:
inode_get_ctime_sec include/linux/fs.h:1747 [inline]
inode_get_ctime include/linux/fs.h:1757 [inline]
inode_update_timestamps+0x43/0x270 fs/inode.c:2014
generic_update_time fs/inode.c:2056 [inline]
inode_update_time fs/inode.c:2076 [inline]
__file_update_time fs/inode.c:2304 [inline]
file_update_time+0x20e/0x2b0 fs/inode.c:2334
fault_dirty_shared_page+0xd9/0x3c0 mm/memory.c:3403
do_shared_fault mm/memory.c:5665 [inline]
do_fault mm/memory.c:5711 [inline]
do_pte_missing mm/memory.c:4234 [inline]
handle_pte_fault mm/memory.c:6052 [inline]
__handle_mm_fault mm/memory.c:6195 [inline]
handle_mm_fault+0x165d/0x2c20 mm/memory.c:6364
do_user_addr_fault+0x3fe/0x1090 arch/x86/mm/fault.c:1387
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
__put_user_nocheck_4+0x3/0x10 arch/x86/lib/putuser.S:97
____sys_recvmsg+0x1a1/0x280 net/socket.c:2847
___sys_recvmsg+0x11f/0x370 net/socket.c:2876
do_recvmmsg+0x1ef/0x540 net/socket.c:2971
__sys_recvmmsg net/socket.c:3045 [inline]
__do_sys_recvmmsg net/socket.c:3068 [inline]
__se_sys_recvmmsg net/socket.c:3061 [inline]
__x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3061
x64_sys_call+0x27a6/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:300
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: 0x0000000068d7acff -> 0x0000000068d7ad00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8203 Comm: syz.3.1510 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================


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