[moderation] [io-uring?] KCSAN: data-race in io_req_defer_failed / io_wq_free_work (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9f16d5e6f220 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134e4530580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3d7fd5be0e73b8b
dashboard link: https://syzkaller.appspot.com/bug?extid=163b6e5f366b31246c15
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [asml.s...@gmail.com ax...@kernel.dk io-u...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9fa7a64f26d5/disk-9f16d5e6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/800b086e8afd/vmlinux-9f16d5e6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/21f5373315cb/bzImage-9f16d5e6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+163b6e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in io_req_defer_failed / io_wq_free_work

write to 0xffff88810e3abf48 of 8 bytes by task 20478 on cpu 1:
io_req_defer_failed+0x73/0x440 io_uring/io_uring.c:922
io_req_task_cancel+0x21/0x30 io_uring/io_uring.c:1335
io_handle_tw_list+0x1b9/0x200 io_uring/io_uring.c:1052
tctx_task_work_run+0x6e/0x1c0 io_uring/io_uring.c:1116
tctx_task_work+0x40/0x80 io_uring/io_uring.c:1134
task_work_run+0x13a/0x1a0 kernel/task_work.c:239
get_signal+0xe78/0x1000 kernel/signal.c:2789
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x62/0x120 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810e3abf48 of 8 bytes by task 20493 on cpu 0:
req_ref_put_and_test io_uring/refs.h:22 [inline]
io_wq_free_work+0x24/0x1b0 io_uring/io_uring.c:1752
io_worker_handle_work+0x4cb/0x9d0 io_uring/io-wq.c:604
io_wq_worker+0x286/0x820 io_uring/io-wq.c:655
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x0000000000180051 -> 0x0000000000980111

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 20493 Comm: iou-wrk-20478 Not tainted 6.12.0-syzkaller-09073-g9f16d5e6f220 #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.