Messages in this thread | | | Date | Mon, 08 Aug 2022 00:35:22 -0700 | Subject | [syzbot] possible deadlock in p9_req_put | From | syzbot <> |
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Hello,
syzbot found the following issue on:
HEAD commit: ca688bff68bc Add linux-next specific files for 20220808 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=104c8666080000 kernel config: https://syzkaller.appspot.com/x/.config?x=4c20e006003cdecb dashboard link: https://syzkaller.appspot.com/bug?extid=50f7e8d06c3768dd97f3 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
Unfortunately, I don't have any reproducer for this issue yet.
IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+50f7e8d06c3768dd97f3@syzkaller.appspotmail.com
============================================ WARNING: possible recursive locking detected 5.19.0-next-20220808-syzkaller #0 Not tainted -------------------------------------------- kworker/0:5/3683 is trying to acquire lock: ffff888026be2c18 (&clnt->lock){+.+.}-{2:2}, at: p9_tag_remove net/9p/client.c:367 [inline] ffff888026be2c18 (&clnt->lock){+.+.}-{2:2}, at: p9_req_put net/9p/client.c:375 [inline] ffff888026be2c18 (&clnt->lock){+.+.}-{2:2}, at: p9_req_put+0xc6/0x250 net/9p/client.c:372
but task is already holding lock: ffff888026be2c18 (&clnt->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] ffff888026be2c18 (&clnt->lock){+.+.}-{2:2}, at: p9_conn_cancel+0xaa/0x970 net/9p/trans_fd.c:192
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&clnt->lock); lock(&clnt->lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
3 locks held by kworker/0:5/3683: #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline] #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline] #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline] #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline] #0: ffff888011864d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x87a/0x1610 kernel/workqueue.c:2260 #1: ffffc90005167da8 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 kernel/workqueue.c:2264 #2: ffff888026be2c18 (&clnt->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #2: ffff888026be2c18 (&clnt->lock){+.+.}-{2:2}, at: p9_conn_cancel+0xaa/0x970 net/9p/trans_fd.c:192
stack backtrace: CPU: 0 PID: 3683 Comm: kworker/0:5 Not tainted 5.19.0-next-20220808-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Workqueue: events p9_read_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2988 [inline] check_deadlock kernel/locking/lockdep.c:3031 [inline] validate_chain kernel/locking/lockdep.c:3816 [inline] __lock_acquire.cold+0x116/0x3a7 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 p9_tag_remove net/9p/client.c:367 [inline] p9_req_put net/9p/client.c:375 [inline] p9_req_put+0xc6/0x250 net/9p/client.c:372 p9_conn_cancel+0x640/0x970 net/9p/trans_fd.c:213 p9_read_work+0x514/0x10c0 net/9p/trans_fd.c:403 process_one_work+0x991/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e4/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 </TASK>
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