[moderation] [fs?] KCSAN: data-race in fifo_open / pipe_poll

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f09079bd04a9 Merge tag 'powerpc-6.16-2' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11b2cd70580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f437300db311c188
dashboard link: https://syzkaller.appspot.com/bug?extid=fc3a5d813a8b4da5b920
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
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/8c9ae317c0ff/disk-f09079bd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/845ca383008a/vmlinux-f09079bd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ec486d641b50/bzImage-f09079bd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fc3a5d...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in fifo_open / pipe_poll

read-write to 0xffff88811abdcdf4 of 4 bytes by task 8841 on cpu 1:
fifo_open+0x2ae/0x5d0 fs/pipe.c:1209
do_dentry_open+0x649/0xa20 fs/open.c:964
vfs_open+0x37/0x1e0 fs/open.c:1094
do_open fs/namei.c:3887 [inline]
path_openat+0x1c5e/0x2170 fs/namei.c:4046
do_filp_open+0x109/0x230 fs/namei.c:4073
do_sys_openat2+0xa6/0x110 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1463
x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
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

read to 0xffff88811abdcdf4 of 4 bytes by task 8836 on cpu 0:
pipe_poll+0x1a8/0x250 fs/pipe.c:689
vfs_poll include/linux/poll.h:82 [inline]
__io_arm_poll_handler+0x1eb/0xb70 io_uring/poll.c:583
io_poll_add+0x69/0xe0 io_uring/poll.c:893
__io_issue_sqe+0xfb/0x2e0 io_uring/io_uring.c:1735
io_issue_sqe+0x53/0x970 io_uring/io_uring.c:1758
io_queue_sqe io_uring/io_uring.c:1965 [inline]
io_submit_sqe io_uring/io_uring.c:2221 [inline]
io_submit_sqes+0x667/0xfd0 io_uring/io_uring.c:2334
__do_sys_io_uring_enter io_uring/io_uring.c:3401 [inline]
__se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3335
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3335
x64_sys_call+0x28c8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:427
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: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 8836 Comm: syz.4.1526 Not tainted 6.16.0-rc1-syzkaller-00003-gf09079bd04a9 #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.