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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e406d57be7bd Merge tag 'mm-nonmm-stable-2025-10-02-15-29' ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1031d942580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6ca22b89f03a1ba8
dashboard link: https://syzkaller.appspot.com/bug?extid=7b22d7a6bd02b165d9fa
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/12abeb865a6e/disk-e406d57b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a86ffc264ace/vmlinux-e406d57b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67ba4bab69a7/bzImage-e406d57b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7b22d7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in pipe_release / pipe_wait_writable

read-write to 0xffff888117fd196c of 4 bytes by task 7186 on cpu 1:
put_pipe_info fs/pipe.c:714 [inline]
pipe_release+0x16a/0x1d0 fs/pipe.c:744
__fput+0x29b/0x650 fs/file_table.c:468
____fput+0x1c/0x30 fs/file_table.c:496
task_work_run+0x12e/0x1a0 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xed/0x110 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888117fd196c of 4 bytes by task 7163 on cpu 0:
pipe_lock fs/pipe.c:90 [inline]
pipe_wait_writable+0x202/0x250 fs/pipe.c:1084
wait_for_space fs/splice.c:1274 [inline]
splice_file_to_pipe+0x12d/0x390 fs/splice.c:1290
do_splice+0xc48/0x10b0 fs/splice.c:1376
__do_splice fs/splice.c:1433 [inline]
__do_sys_splice fs/splice.c:1636 [inline]
__se_sys_splice+0x26c/0x3a0 fs/splice.c:1618
__x64_sys_splice+0x78/0x90 fs/splice.c:1618
x64_sys_call+0x28a7/0x3000 arch/x86/include/generated/asm/syscalls_64.h:276
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: 0x00000002 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7163 Comm: syz.2.1185 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================


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