kernel read not supported for file /zero (pid: 19505 comm: kworker/1:0) kernel read not supported for file /zero (pid: 19505 comm: kworker/1:0) ============================================ WARNING: possible recursive locking detected 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0 Not tainted -------------------------------------------- kworker/1:0/19505 is trying to acquire lock: ffff000116b00018 (&clnt->lock){+.+.}-{2:2}, at: p9_tag_remove net/9p/client.c:367 [inline] ffff000116b00018 (&clnt->lock){+.+.}-{2:2}, at: p9_req_put+0x58/0x174 net/9p/client.c:375 but task is already holding lock: ffff000116b00018 (&clnt->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] ffff000116b00018 (&clnt->lock){+.+.}-{2:2}, at: p9_conn_cancel+0x48/0x270 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/1:0/19505: #0: ffff0000c0010738 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x270/0x504 kernel/workqueue.c:2262 #1: ffff800020043d80 ((work_completion)(&m->rq)){+.+.}-{0:0}, at: process_one_work+0x29c/0x504 kernel/workqueue.c:2264 #2: ffff000116b00018 (&clnt->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #2: ffff000116b00018 (&clnt->lock){+.+.}-{2:2}, at: p9_conn_cancel+0x48/0x270 net/9p/trans_fd.c:192 stack backtrace: CPU: 1 PID: 19505 Comm: kworker/1:0 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022 Workqueue: events p9_read_work Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156 show_stack+0x2c/0x54 arch/arm64/kernel/stacktrace.c:163 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 __lock_acquire+0x808/0x30a4 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x6c/0xb4 kernel/locking/spinlock.c:162 p9_tag_remove net/9p/client.c:367 [inline] p9_req_put+0x58/0x174 net/9p/client.c:375 p9_client_cb+0x4c/0x60 net/9p/client.c:427 p9_conn_cancel+0x210/0x270 net/9p/trans_fd.c:213 p9_read_work+0x4e8/0x620 net/9p/trans_fd.c:403 process_one_work+0x2d8/0x504 kernel/workqueue.c:2289 worker_thread+0x340/0x610 kernel/workqueue.c:2436 kthread+0x12c/0x158 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860