syzbot

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BUG: KCSAN: data-race in io_flush_timeouts / io_issue_sqe

read-write to 0xffff888121fda210 of 4 bytes by task 5467 on cpu 1:
 io_get_cqe_overflow io_uring/io_uring.h:256 [inline]
 io_get_cqe io_uring/io_uring.h:271 [inline]
 io_fill_cqe_req io_uring/io_uring.h:293 [inline]
 io_req_complete_post io_uring/io_uring.c:986 [inline]
 io_issue_sqe+0x1f9/0xa70 io_uring/io_uring.c:1822
 io_wq_submit_work+0x3f7/0x5f0 io_uring/io_uring.c:1928
 io_worker_handle_work+0x44d/0x9b0 io_uring/io-wq.c:650
 io_wq_worker+0x22d/0x860 io_uring/io-wq.c:704
 ret_from_fork+0x148/0x280 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffff888121fda210 of 4 bytes by task 5450 on cpu 0:
 io_flush_timeouts+0x62/0x1e0 io_uring/timeout.c:133
 __io_commit_cqring_flush+0xeb/0x100 io_uring/io_uring.c:544
 io_commit_cqring_flush io_uring/io_uring.h:531 [inline]
 __io_cq_unlock_post io_uring/io_uring.c:571 [inline]
 __io_submit_flush_completions+0xaf1/0xb10 io_uring/io_uring.c:1535
 io_submit_flush_completions io_uring/io_uring.h:239 [inline]
 ctx_flush_and_put+0x9b/0x150 io_uring/io_uring.c:1093
 io_handle_tw_list+0x20e/0x230 io_uring/io_uring.c:1134
 tctx_task_work_run+0x42/0x160 io_uring/io_uring.c:1182
 tctx_task_work+0x3f/0x80 io_uring/io_uring.c:1200
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 get_signal+0xe09/0xf60 kernel/signal.c:2807
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x1d3/0x2a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000003db -> 0x000003dc

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5450 Comm: syz.4.651 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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