possible deadlock in __io_queue

duplicates (1):
Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
possible deadlock in io_queue_linked_timeout io-uring fs	C	error		3	1351d	1353d	0/26	closed as dup on 2020/08/10 16:02

duplicates (1):

error

1351d

1353d

0/26

closed as dup on 2020/08/10 16:02

Title	Replies (including bot)	Last reply
possible deadlock in __io_queue_deferred	5 (6)	2020/08/11 14:45
possible deadlock in io_queue_linked_timeout	1 (2)	2020/08/10 15:59

============================================ WARNING: possible recursive locking detected 5.8.0-syzkaller #0 Not tainted -------------------------------------------- syz-executor287/6816 is trying to acquire lock: ffff888093cdb4d8 (&ctx->completion_lock){....}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:379 [inline] ffff888093cdb4d8 (&ctx->completion_lock){....}-{2:2}, at: io_queue_linked_timeout fs/io_uring.c:5928 [inline] ffff888093cdb4d8 (&ctx->completion_lock){....}-{2:2}, at: __io_queue_async_work fs/io_uring.c:1192 [inline] ffff888093cdb4d8 (&ctx->completion_lock){....}-{2:2}, at: __io_queue_deferred+0x36a/0x790 fs/io_uring.c:1237 but task is already holding lock: ffff888093cdb4d8 (&ctx->completion_lock){....}-{2:2}, at: io_cqring_overflow_flush+0xc6/0xab0 fs/io_uring.c:1333 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&ctx->completion_lock); lock(&ctx->completion_lock); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by syz-executor287/6816: #0: ffff888093cdb4d8 (&ctx->completion_lock){....}-{2:2}, at: io_cqring_overflow_flush+0xc6/0xab0 fs/io_uring.c:1333 stack backtrace: CPU: 1 PID: 6816 Comm: syz-executor287 Not tainted 5.8.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1f0/0x31e lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:2391 [inline] check_deadlock kernel/locking/lockdep.c:2432 [inline] validate_chain+0x69a4/0x88a0 kernel/locking/lockdep.c:3202 __lock_acquire+0x1161/0x2ab0 kernel/locking/lockdep.c:4426 lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x67/0x80 kernel/locking/spinlock.c:167 spin_lock_irq include/linux/spinlock.h:379 [inline] io_queue_linked_timeout fs/io_uring.c:5928 [inline] __io_queue_async_work fs/io_uring.c:1192 [inline] __io_queue_deferred+0x36a/0x790 fs/io_uring.c:1237 io_cqring_overflow_flush+0x774/0xab0 fs/io_uring.c:1359 io_ring_ctx_wait_and_kill+0x2a1/0x570 fs/io_uring.c:7808 io_uring_release+0x59/0x70 fs/io_uring.c:7829 __fput+0x34f/0x7b0 fs/file_table.c:281 task_work_run+0x137/0x1c0 kernel/task_work.c:135 exit_task_work include/linux/task_work.h:25 [inline] do_exit+0x5f3/0x1f20 kernel/exit.c:806 do_group_exit+0x161/0x2d0 kernel/exit.c:903 __do_sys_exit_group+0x13/0x20 kernel/exit.c:914 __se_sys_exit_group+0x10/0x10 kernel/exit.c:912 __x64_sys_exit_group+0x37/0x40 kernel/exit.c:912 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x43f598 Code: Bad RIP value. RSP: 002b:00007fffdac2bf58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f598 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00000000004beda8 R08: 00000000000000e7 R09: ffffffffffffffd0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000006d11a0 R14: 0000000000000000 R15: 0000000000000000