From: syzbot <[email protected]>
To: [email protected], [email protected],
[email protected], [email protected],
[email protected], [email protected]
Subject: possible deadlock in __io_queue_deferred
Date: Mon, 10 Aug 2020 08:36:17 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: 449dc8c9 Merge tag 'for-v5.9' of git://git.kernel.org/pub/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14d41e02900000
kernel config: https://syzkaller.appspot.com/x/.config?x=9d25235bf0162fbc
dashboard link: https://syzkaller.appspot.com/bug?extid=996f91b6ec3812c48042
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133c9006900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1191cb1a900000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
============================================
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
---
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next reply other threads:[~2020-08-10 15:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-10 15:36 syzbot [this message]
2020-08-10 15:55 ` possible deadlock in __io_queue_deferred Jens Axboe
2020-08-11 14:00 ` Stefano Garzarella
2020-08-11 14:21 ` Jens Axboe
2020-08-11 14:44 ` Stefano Garzarella
2020-08-11 14:45 ` Jens Axboe
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