[syzbot] [io-uring?] KCSAN: data-race in io_req_task_cancel / io_wq_free_work

[syzbot <syzbot+903a2ad71fb3f1e47cf5@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    92b71befc349 Merge tag 'objtool-urgent-2025-04-01' of git:..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11195404580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a8120cade23cf14e
dashboard link: https://syzkaller.appspot.com/bug?extid=903a2ad71fb3f1e47cf5
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2e7df7bc2f52/disk-92b71bef.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/be59123d5efb/vmlinux-92b71bef.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c9eff86053e/bzImage-92b71bef.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+903a2ad71fb3f1e47cf5@syzkaller.appspotmail.com

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

write to 0xffff888117207448 of 8 bytes by task 3861 on cpu 1:
 req_set_fail io_uring/io_uring.h:-1 [inline]
 io_req_defer_failed io_uring/io_uring.c:927 [inline]
 io_req_task_cancel+0x7c/0x1a0 io_uring/io_uring.c:1360
 io_handle_tw_list+0x194/0x1d0 io_uring/io_uring.c:1057
 tctx_task_work_run+0x6e/0x1c0 io_uring/io_uring.c:1121
 tctx_task_work+0x44/0x80 io_uring/io_uring.c:1139
 task_work_run+0x13c/0x1b0 kernel/task_work.c:227
 get_signal+0xee2/0x1080 kernel/signal.c:2809
 arch_do_signal_or_restart+0x9a/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/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888117207448 of 8 bytes by task 3871 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:1799
 io_worker_handle_work+0x4c9/0x9f0 io_uring/io-wq.c:618
 io_wq_worker+0x277/0x850 io_uring/io-wq.c:669
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000180051 -> 0x0000000000980111

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3871 Comm: iou-wrk-3861 Not tainted 6.14.0-syzkaller-12508-g92b71befc349 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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