[syzbot] inconsistent lock state in p9_fd_request

[syzbot <syzbot+c4455787f92b4f78d5b1@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    568035b01cfb Linux 6.0-rc1
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a5b2a5080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e706e91b2a433db
dashboard link: https://syzkaller.appspot.com/bug?extid=c4455787f92b4f78d5b1
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+c4455787f92b4f78d5b1@syzkaller.appspotmail.com

================================
WARNING: inconsistent lock state
6.0.0-rc1-syzkaller #0 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
syz-executor.3/5046 [HC0[0]:SC0[0]:HE1:SE1] takes:
ffff88801e763818 (&clnt->lock){?...}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline]
ffff88801e763818 (&clnt->lock){?...}-{2:2}, at: p9_fd_request+0x85/0x330 net/9p/trans_fd.c:672
{IN-HARDIRQ-W} state was registered at:
  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
  req_done+0x1de/0x2e0 net/9p/trans_virtio.c:148
  vring_interrupt drivers/virtio/virtio_ring.c:2454 [inline]
  vring_interrupt+0x29d/0x3d0 drivers/virtio/virtio_ring.c:2429
  __handle_irq_event_percpu+0x227/0x870 kernel/irq/handle.c:158
  handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
  handle_irq_event+0xa7/0x1e0 kernel/irq/handle.c:210
  handle_edge_irq+0x25f/0xd00 kernel/irq/chip.c:819
  generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
  handle_irq arch/x86/kernel/irq.c:231 [inline]
  __common_interrupt+0x9d/0x210 arch/x86/kernel/irq.c:250
  common_interrupt+0xa4/0xc0 arch/x86/kernel/irq.c:240
  asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:640
  lock_is_held_type+0xe/0x140 kernel/locking/lockdep.c:5694
  lock_is_held include/linux/lockdep.h:283 [inline]
  rcu_read_lock_sched_held+0x3a/0x70 kernel/rcu/update.c:125
  trace_lock_release include/trace/events/lock.h:69 [inline]
  lock_release+0x560/0x780 kernel/locking/lockdep.c:5677
  rcu_lock_release include/linux/rcupdate.h:285 [inline]
  rcu_read_unlock include/linux/rcupdate.h:739 [inline]
  batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
  batadv_nc_worker+0x86b/0xfa0 net/batman-adv/network-coding.c:719
  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
irq event stamp: 527
hardirqs last  enabled at (527): [<ffffffff8982206f>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
hardirqs last  enabled at (527): [<ffffffff8982206f>] _raw_spin_unlock_irq+0x1f/0x40 kernel/locking/spinlock.c:202
hardirqs last disabled at (526): [<ffffffff89821e41>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline]
hardirqs last disabled at (526): [<ffffffff89821e41>] _raw_spin_lock_irq+0x41/0x50 kernel/locking/spinlock.c:170
softirqs last  enabled at (0): [<ffffffff8146165e>] copy_process+0x213e/0x7090 kernel/fork.c:2201
softirqs last disabled at (0): [<0000000000000000>] 0x0

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&clnt->lock);
  <Interrupt>
    lock(&clnt->lock);

 *** DEADLOCK ***

no locks held by syz-executor.3/5046.

stack backtrace:
CPU: 0 PID: 5046 Comm: syz-executor.3 Not tainted 6.0.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_usage_bug kernel/locking/lockdep.c:3961 [inline]
 valid_state kernel/locking/lockdep.c:3973 [inline]
 mark_lock_irq kernel/locking/lockdep.c:4176 [inline]
 mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4632
 mark_lock kernel/locking/lockdep.c:4596 [inline]
 mark_usage kernel/locking/lockdep.c:4541 [inline]
 __lock_acquire+0x847/0x56d0 kernel/locking/lockdep.c:5007
 lock_acquire kernel/locking/lockdep.c:5666 [inline]
 lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:349 [inline]
 p9_fd_request+0x85/0x330 net/9p/trans_fd.c:672
 p9_client_rpc+0x2f0/0xce0 net/9p/client.c:660
 p9_client_version net/9p/client.c:880 [inline]
 p9_client_create+0xaec/0x1070 net/9p/client.c:985
 v9fs_session_init+0x1e2/0x1810 fs/9p/v9fs.c:408
 v9fs_mount+0xba/0xc90 fs/9p/vfs_super.c:126
 legacy_get_tree+0x105/0x220 fs/fs_context.c:610
 vfs_get_tree+0x89/0x2f0 fs/super.c:1530
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f072b089279
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f072c122168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f072b19bf80 RCX: 00007f072b089279
RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 00007f072b0e3189 R08: 0000000020000400 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcabcfe84f R14: 00007f072c122300 R15: 0000000000022000
 </TASK>


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