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* possible deadlock in lock_timer_base
@ 2021-01-03  6:59 syzbot
       [not found] ` <20210103094904.14908-1-hdanton@sina.com>
  2024-03-19 10:33 ` [syzbot] [batman?] [bpf?] " syzbot
  0 siblings, 2 replies; 7+ messages in thread
From: syzbot @ 2021-01-03  6:59 UTC (permalink / raw)
  To: akpm, christian, linux-kernel, shakeelb, syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    d7a03a44 Add linux-next specific files for 20201223
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=155fb7b7500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ea251547cbb170c5
dashboard link: https://syzkaller.appspot.com/bug?extid=8983d6d4f7df556be565
compiler:       gcc (GCC) 10.1.0-syz 20200507

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+8983d6d4f7df556be565@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.10.0-next-20201223-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/9817 is trying to acquire lock:
ffffffff8b48b998 (allocation_wait.lock){..-.}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137

but task is already holding lock:
ffff8880b9e24898 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x5a/0x1f0 kernel/time/timer.c:944

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&base->lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
       lock_timer_base+0x5a/0x1f0 kernel/time/timer.c:944
       __mod_timer+0x398/0xe30 kernel/time/timer.c:1017
       __queue_delayed_work+0x1a7/0x270 kernel/workqueue.c:1655
       queue_delayed_work_on+0xd1/0xe0 kernel/workqueue.c:1680
       psi_task_change+0x142/0x220 kernel/sched/psi.c:807
       psi_enqueue kernel/sched/stats.h:82 [inline]
       enqueue_task kernel/sched/core.c:1592 [inline]
       activate_task kernel/sched/core.c:1615 [inline]
       wake_up_new_task+0x9f2/0xdd0 kernel/sched/core.c:3834
       kernel_clone+0x1f0/0xab0 kernel/fork.c:2489
       kernel_thread+0xb5/0xf0 kernel/fork.c:2517
       rest_init+0x23/0x388 init/main.c:687
       start_kernel+0x470/0x491 init/main.c:1064
       secondary_startup_64_no_verify+0xb0/0xbb

-> #2 (&rq->lock){-.-.}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
       _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
       rq_lock kernel/sched/sched.h:1318 [inline]
       task_fork_fair+0x74/0x4d0 kernel/sched/fair.c:10767
       sched_fork+0x3fc/0xbd0 kernel/sched/core.c:3764
       copy_process+0x1d61/0x6fc0 kernel/fork.c:2070
       kernel_clone+0xe7/0xab0 kernel/fork.c:2465
       kernel_thread+0xb5/0xf0 kernel/fork.c:2517
       rest_init+0x23/0x388 init/main.c:687
       start_kernel+0x470/0x491 init/main.c:1064
       secondary_startup_64_no_verify+0xb0/0xbb

-> #1 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
       try_to_wake_up+0x98/0x13b0 kernel/sched/core.c:3335
       autoremove_wake_function+0x12/0x140 kernel/sched/wait.c:404
       __wake_up_common+0x147/0x650 kernel/sched/wait.c:108
       __wake_up_common_lock+0xd0/0x130 kernel/sched/wait.c:138
       __kfence_alloc+0xa0/0xbc0 mm/kfence/core.c:710
       kfence_alloc include/linux/kfence.h:108 [inline]
       slab_alloc_node mm/slub.c:2826 [inline]
       kmem_cache_alloc_node_trace+0x28d/0x3d0 mm/slub.c:2953
       kmalloc_node include/linux/slab.h:570 [inline]
       kzalloc_node include/linux/slab.h:693 [inline]
       alloc_worker kernel/workqueue.c:1826 [inline]
       create_worker+0xfe/0x6d0 kernel/workqueue.c:1923
       maybe_create_worker kernel/workqueue.c:2094 [inline]
       manage_workers kernel/workqueue.c:2146 [inline]
       worker_thread+0xaef/0x1120 kernel/workqueue.c:2393
       kthread+0x3b1/0x4a0 kernel/kthread.c:292
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

-> #0 (allocation_wait.lock){..-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:2868 [inline]
       check_prevs_add kernel/locking/lockdep.c:2993 [inline]
       validate_chain kernel/locking/lockdep.c:3608 [inline]
       __lock_acquire+0x2ade/0x5500 kernel/locking/lockdep.c:4832
       lock_acquire kernel/locking/lockdep.c:5437 [inline]
       lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
       __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137
       __kfence_alloc+0xa0/0xbc0 mm/kfence/core.c:710
       kfence_alloc include/linux/kfence.h:108 [inline]
       slab_alloc_node mm/slub.c:2826 [inline]
       slab_alloc mm/slub.c:2911 [inline]
       kmem_cache_alloc+0x259/0x470 mm/slub.c:2916
       kmem_cache_zalloc include/linux/slab.h:672 [inline]
       fill_pool+0x264/0x5c0 lib/debugobjects.c:171
       __debug_object_init+0x7a/0xd10 lib/debugobjects.c:560
       debug_object_init lib/debugobjects.c:615 [inline]
       debug_object_activate+0x32c/0x3e0 lib/debugobjects.c:701
       debug_timer_activate kernel/time/timer.c:727 [inline]
       __mod_timer+0x77d/0xe30 kernel/time/timer.c:1048
       __queue_delayed_work+0x1a7/0x270 kernel/workqueue.c:1655
       queue_delayed_work_on+0xd1/0xe0 kernel/workqueue.c:1680
       queue_delayed_work include/linux/workqueue.h:522 [inline]
       schedule_delayed_work include/linux/workqueue.h:626 [inline]
       unaccount_event kernel/events/core.c:4703 [inline]
       _free_event+0xf49/0x1300 kernel/events/core.c:4812
       put_event kernel/events/core.c:4935 [inline]
       perf_event_release_kernel+0xa24/0xe00 kernel/events/core.c:5050
       perf_release+0x33/0x40 kernel/events/core.c:5060
       __fput+0x283/0x920 fs/file_table.c:280
       task_work_run+0xdd/0x190 kernel/task_work.c:140
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
       exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201
       __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
       syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
       entry_SYSCALL_64_after_hwframe+0x44/0xa9

other info that might help us debug this:

Chain exists of:
  allocation_wait.lock --> &rq->lock --> &base->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&base->lock);
                               lock(&rq->lock);
                               lock(&base->lock);
  lock(allocation_wait.lock);

 *** DEADLOCK ***

1 lock held by syz-executor.0/9817:
 #0: ffff8880b9e24898 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x5a/0x1f0 kernel/time/timer.c:944

stack backtrace:
CPU: 0 PID: 9817 Comm: syz-executor.0 Not tainted 5.10.0-next-20201223-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2117
 check_prev_add kernel/locking/lockdep.c:2868 [inline]
 check_prevs_add kernel/locking/lockdep.c:2993 [inline]
 validate_chain kernel/locking/lockdep.c:3608 [inline]
 __lock_acquire+0x2ade/0x5500 kernel/locking/lockdep.c:4832
 lock_acquire kernel/locking/lockdep.c:5437 [inline]
 lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
 __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137
 __kfence_alloc+0xa0/0xbc0 mm/kfence/core.c:710
 kfence_alloc include/linux/kfence.h:108 [inline]
 slab_alloc_node mm/slub.c:2826 [inline]
 slab_alloc mm/slub.c:2911 [inline]
 kmem_cache_alloc+0x259/0x470 mm/slub.c:2916
 kmem_cache_zalloc include/linux/slab.h:672 [inline]
 fill_pool+0x264/0x5c0 lib/debugobjects.c:171
 __debug_object_init+0x7a/0xd10 lib/debugobjects.c:560
 debug_object_init lib/debugobjects.c:615 [inline]
 debug_object_activate+0x32c/0x3e0 lib/debugobjects.c:701
 debug_timer_activate kernel/time/timer.c:727 [inline]
 __mod_timer+0x77d/0xe30 kernel/time/timer.c:1048
 __queue_delayed_work+0x1a7/0x270 kernel/workqueue.c:1655
 queue_delayed_work_on+0xd1/0xe0 kernel/workqueue.c:1680
 queue_delayed_work include/linux/workqueue.h:522 [inline]
 schedule_delayed_work include/linux/workqueue.h:626 [inline]
 unaccount_event kernel/events/core.c:4703 [inline]
 _free_event+0xf49/0x1300 kernel/events/core.c:4812
 put_event kernel/events/core.c:4935 [inline]
 perf_event_release_kernel+0xa24/0xe00 kernel/events/core.c:5050
 perf_release+0x33/0x40 kernel/events/core.c:5060
 __fput+0x283/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x190 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x417bf1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 1a 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffe977a18a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417bf1
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000ab3 R09: 00000000e0282ab7
R10: 00007ffe977a1980 R11: 0000000000000293 R12: 000000000119ca00
R13: 000000000119ca00 R14: 00000000000003e8 R15: 000000000119bf8c


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: possible deadlock in lock_timer_base
       [not found] ` <20210103094904.14908-1-hdanton@sina.com>
@ 2021-01-04 10:54   ` Marco Elver
  0 siblings, 0 replies; 7+ messages in thread
From: Marco Elver @ 2021-01-04 10:54 UTC (permalink / raw)
  To: Hillf Danton
  Cc: syzbot, Andrew Morton, LKML, Alexander Potapenko, Dmitry Vyukov,
	syzkaller-bugs

On Sun, 3 Jan 2021 at 10:49, Hillf Danton <hdanton@sina.com> wrote:
>
> Sat, 02 Jan 2021 22:59:11 -0800
> > syzbot found the following issue on:
> >
> > HEAD commit:    d7a03a44 Add linux-next specific files for 20201223
> > git tree:       linux-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=155fb7b7500000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=ea251547cbb170c5
> > dashboard link: https://syzkaller.appspot.com/bug?extid=8983d6d4f7df556be565
> > compiler:       gcc (GCC) 10.1.0-syz 20200507
> >
> > 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+8983d6d4f7df556be565@syzkaller.appspotmail.com
> >
> > ======================================================
> > WARNING: possible circular locking dependency detected
> > 5.10.0-next-20201223-syzkaller #0 Not tainted
> > ------------------------------------------------------
> > syz-executor.0/9817 is trying to acquire lock:
> > ffffffff8b48b998 (allocation_wait.lock){..-.}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137
> >
> > but task is already holding lock:
> > ffff8880b9e24898 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x5a/0x1f0 kernel/time/timer.c:944
> >
> > which lock already depends on the new lock.
> >
> >
> > the existing dependency chain (in reverse order) is:
> >
> > -> #3 (&base->lock){-.-.}-{2:2}:
> >        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> >        _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
> >        lock_timer_base+0x5a/0x1f0 kernel/time/timer.c:944
> >        __mod_timer+0x398/0xe30 kernel/time/timer.c:1017
> >        __queue_delayed_work+0x1a7/0x270 kernel/workqueue.c:1655
> >        queue_delayed_work_on+0xd1/0xe0 kernel/workqueue.c:1680
> >        psi_task_change+0x142/0x220 kernel/sched/psi.c:807
> >        psi_enqueue kernel/sched/stats.h:82 [inline]
> >        enqueue_task kernel/sched/core.c:1592 [inline]
> >        activate_task kernel/sched/core.c:1615 [inline]
> >        wake_up_new_task+0x9f2/0xdd0 kernel/sched/core.c:3834
> >        kernel_clone+0x1f0/0xab0 kernel/fork.c:2489
> >        kernel_thread+0xb5/0xf0 kernel/fork.c:2517
> >        rest_init+0x23/0x388 init/main.c:687
> >        start_kernel+0x470/0x491 init/main.c:1064
> >        secondary_startup_64_no_verify+0xb0/0xbb
> >
> > -> #2 (&rq->lock){-.-.}-{2:2}:
> >        __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
> >        _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
> >        rq_lock kernel/sched/sched.h:1318 [inline]
> >        task_fork_fair+0x74/0x4d0 kernel/sched/fair.c:10767
> >        sched_fork+0x3fc/0xbd0 kernel/sched/core.c:3764
> >        copy_process+0x1d61/0x6fc0 kernel/fork.c:2070
> >        kernel_clone+0xe7/0xab0 kernel/fork.c:2465
> >        kernel_thread+0xb5/0xf0 kernel/fork.c:2517
> >        rest_init+0x23/0x388 init/main.c:687
> >        start_kernel+0x470/0x491 init/main.c:1064
> >        secondary_startup_64_no_verify+0xb0/0xbb
> >
> > -> #1 (&p->pi_lock){-.-.}-{2:2}:
> >        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> >        _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
> >        try_to_wake_up+0x98/0x13b0 kernel/sched/core.c:3335
> >        autoremove_wake_function+0x12/0x140 kernel/sched/wait.c:404
> >        __wake_up_common+0x147/0x650 kernel/sched/wait.c:108
> >        __wake_up_common_lock+0xd0/0x130 kernel/sched/wait.c:138
> >        __kfence_alloc+0xa0/0xbc0 mm/kfence/core.c:710
> >        kfence_alloc include/linux/kfence.h:108 [inline]
> >        slab_alloc_node mm/slub.c:2826 [inline]
> >        kmem_cache_alloc_node_trace+0x28d/0x3d0 mm/slub.c:2953
> >        kmalloc_node include/linux/slab.h:570 [inline]
> >        kzalloc_node include/linux/slab.h:693 [inline]
> >        alloc_worker kernel/workqueue.c:1826 [inline]
> >        create_worker+0xfe/0x6d0 kernel/workqueue.c:1923
> >        maybe_create_worker kernel/workqueue.c:2094 [inline]
> >        manage_workers kernel/workqueue.c:2146 [inline]
> >        worker_thread+0xaef/0x1120 kernel/workqueue.c:2393
> >        kthread+0x3b1/0x4a0 kernel/kthread.c:292
> >        ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
> >
> > -> #0 (allocation_wait.lock){..-.}-{2:2}:
> >        check_prev_add kernel/locking/lockdep.c:2868 [inline]
> >        check_prevs_add kernel/locking/lockdep.c:2993 [inline]
> >        validate_chain kernel/locking/lockdep.c:3608 [inline]
> >        __lock_acquire+0x2ade/0x5500 kernel/locking/lockdep.c:4832
> >        lock_acquire kernel/locking/lockdep.c:5437 [inline]
> >        lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402
> >        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> >        _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
> >        __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137
> >        __kfence_alloc+0xa0/0xbc0 mm/kfence/core.c:710
> >        kfence_alloc include/linux/kfence.h:108 [inline]
> >        slab_alloc_node mm/slub.c:2826 [inline]
> >        slab_alloc mm/slub.c:2911 [inline]
> >        kmem_cache_alloc+0x259/0x470 mm/slub.c:2916
> >        kmem_cache_zalloc include/linux/slab.h:672 [inline]
> >        fill_pool+0x264/0x5c0 lib/debugobjects.c:171
> >        __debug_object_init+0x7a/0xd10 lib/debugobjects.c:560
> >        debug_object_init lib/debugobjects.c:615 [inline]
> >        debug_object_activate+0x32c/0x3e0 lib/debugobjects.c:701
> >        debug_timer_activate kernel/time/timer.c:727 [inline]
> >        __mod_timer+0x77d/0xe30 kernel/time/timer.c:1048
> >        __queue_delayed_work+0x1a7/0x270 kernel/workqueue.c:1655
> >        queue_delayed_work_on+0xd1/0xe0 kernel/workqueue.c:1680
> >        queue_delayed_work include/linux/workqueue.h:522 [inline]
> >        schedule_delayed_work include/linux/workqueue.h:626 [inline]
> >        unaccount_event kernel/events/core.c:4703 [inline]
> >        _free_event+0xf49/0x1300 kernel/events/core.c:4812
> >        put_event kernel/events/core.c:4935 [inline]
> >        perf_event_release_kernel+0xa24/0xe00 kernel/events/core.c:5050
> >        perf_release+0x33/0x40 kernel/events/core.c:5060
> >        __fput+0x283/0x920 fs/file_table.c:280
> >        task_work_run+0xdd/0x190 kernel/task_work.c:140
> >        tracehook_notify_resume include/linux/tracehook.h:189 [inline]
> >        exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
> >        exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201
> >        __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
> >        syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
> >        entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >
> > other info that might help us debug this:
> >
> > Chain exists of:
> >   allocation_wait.lock --> &rq->lock --> &base->lock
> >
> >  Possible unsafe locking scenario:
> >
> >        CPU0                    CPU1
> >        ----                    ----
> >   lock(&base->lock);
> >                                lock(&rq->lock);
> >                                lock(&base->lock);
> >   lock(allocation_wait.lock);
> >
> >  *** DEADLOCK ***
> >
> > 1 lock held by syz-executor.0/9817:
> >  #0: ffff8880b9e24898 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x5a/0x1f0 kernel/time/timer.c:944
> >
> > stack backtrace:
> > CPU: 0 PID: 9817 Comm: syz-executor.0 Not tainted 5.10.0-next-20201223-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Call Trace:
> >  __dump_stack lib/dump_stack.c:79 [inline]
> >  dump_stack+0x107/0x163 lib/dump_stack.c:120
> >  check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2117
> >  check_prev_add kernel/locking/lockdep.c:2868 [inline]
> >  check_prevs_add kernel/locking/lockdep.c:2993 [inline]
> >  validate_chain kernel/locking/lockdep.c:3608 [inline]
> >  __lock_acquire+0x2ade/0x5500 kernel/locking/lockdep.c:4832
> >  lock_acquire kernel/locking/lockdep.c:5437 [inline]
> >  lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402
> >  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> >  _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
> >  __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137
> >  __kfence_alloc+0xa0/0xbc0 mm/kfence/core.c:710
> >  kfence_alloc include/linux/kfence.h:108 [inline]
> >  slab_alloc_node mm/slub.c:2826 [inline]
> >  slab_alloc mm/slub.c:2911 [inline]
> >  kmem_cache_alloc+0x259/0x470 mm/slub.c:2916
> >  kmem_cache_zalloc include/linux/slab.h:672 [inline]
> >  fill_pool+0x264/0x5c0 lib/debugobjects.c:171
> >  __debug_object_init+0x7a/0xd10 lib/debugobjects.c:560
> >  debug_object_init lib/debugobjects.c:615 [inline]
> >  debug_object_activate+0x32c/0x3e0 lib/debugobjects.c:701
> >  debug_timer_activate kernel/time/timer.c:727 [inline]
> >  __mod_timer+0x77d/0xe30 kernel/time/timer.c:1048
> >  __queue_delayed_work+0x1a7/0x270 kernel/workqueue.c:1655
> >  queue_delayed_work_on+0xd1/0xe0 kernel/workqueue.c:1680
> >  queue_delayed_work include/linux/workqueue.h:522 [inline]
> >  schedule_delayed_work include/linux/workqueue.h:626 [inline]
> >  unaccount_event kernel/events/core.c:4703 [inline]
> >  _free_event+0xf49/0x1300 kernel/events/core.c:4812
> >  put_event kernel/events/core.c:4935 [inline]
> >  perf_event_release_kernel+0xa24/0xe00 kernel/events/core.c:5050
> >  perf_release+0x33/0x40 kernel/events/core.c:5060
> >  __fput+0x283/0x920 fs/file_table.c:280
> >  task_work_run+0xdd/0x190 kernel/task_work.c:140
> >  tracehook_notify_resume include/linux/tracehook.h:189 [inline]
> >  exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
> >  exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201
> >  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
> >  syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
> >  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > RIP: 0033:0x417bf1
> > Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 1a 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
> > RSP: 002b:00007ffe977a18a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
> > RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417bf1
> > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000003
> > RBP: 0000000000000001 R08: 0000000000000ab3 R09: 00000000e0282ab7
> > R10: 00007ffe977a1980 R11: 0000000000000293 R12: 000000000119ca00
> > R13: 000000000119ca00 R14: 00000000000003e8 R15: 000000000119bf8c
>
> To avoid ttwu, open code wait_event_timeout().

Thanks, I'll send a patch.

> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -94,9 +94,6 @@ DEFINE_STATIC_KEY_FALSE(kfence_allocatio
>  /* Gates the allocation, ensuring only one succeeds in a given period. */
>  static atomic_t allocation_gate = ATOMIC_INIT(1);
>
> -/* Wait queue to wake up allocation-gate timer task. */
> -static DECLARE_WAIT_QUEUE_HEAD(allocation_wait);
> -
>  /* Statistics counters for debugfs. */
>  enum kfence_counter_id {
>         KFENCE_COUNTER_ALLOCATED,
> @@ -586,6 +583,8 @@ late_initcall(kfence_debugfs_init);
>  static struct delayed_work kfence_timer;
>  static void toggle_allocation_gate(struct work_struct *work)
>  {
> +       unsigned long end;
> +
>         if (!READ_ONCE(kfence_enabled))
>                 return;
>
> @@ -596,7 +595,11 @@ static void toggle_allocation_gate(struc
>          * Await an allocation. Timeout after 1 second, in case the kernel stops
>          * doing allocations, to avoid stalling this worker task for too long.
>          */
> -       wait_event_timeout(allocation_wait, atomic_read(&allocation_gate) != 0, HZ);
> +       for (end = jiffies + HZ; jiffies < end;) {
> +               if (atomic_read(&allocation_gate) != 0)
> +                       break;

We need set_current_state(TASK_UNINTERRUPTIBLE) here, otherwise
schedule_timeout() has no effect. I'll fix this...

> +               schedule_timeout(1);
> +       }

__set_current_state(TASK_RUNNING);

>         /* Disable static key and reset timer. */
>         static_branch_disable(&kfence_allocation_key);
> @@ -707,7 +710,6 @@ void *__kfence_alloc(struct kmem_cache *
>          */
>         if (atomic_read(&allocation_gate) || atomic_inc_return(&allocation_gate) > 1)
>                 return NULL;
> -       wake_up(&allocation_wait);
>
>         if (!READ_ONCE(kfence_enabled))
>                 return NULL;
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20210103094904.14908-1-hdanton%40sina.com.

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [syzbot] [batman?] [bpf?] possible deadlock in lock_timer_base
  2021-01-03  6:59 possible deadlock in lock_timer_base syzbot
       [not found] ` <20210103094904.14908-1-hdanton@sina.com>
@ 2024-03-19 10:33 ` syzbot
  2024-03-19 13:19   ` Sven Eckelmann
  2024-03-23 22:46   ` Hillf Danton
  1 sibling, 2 replies; 7+ messages in thread
From: syzbot @ 2024-03-19 10:33 UTC (permalink / raw)
  To: a, akpm, andrii, ast, b.a.t.m.a.n, bpf, christian, daniel, davem,
	dvyukov, edumazet, elver, glider, hdanton, jakub, jannh,
	john.fastabend, kasan-dev, kuba, linux-kernel, linux-mm,
	mareklindner, mark.rutland, netdev, pabeni, shakeelb, sven, sw,
	syzkaller-bugs

syzbot has found a reproducer for the following issue on:

HEAD commit:    35c3e2791756 Revert "net: Re-use and set mono_delivery_tim..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=10569181180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
dashboard link: https://syzkaller.appspot.com/bug?extid=8983d6d4f7df556be565
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13d9fa4e180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=137afac9180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/26b55a26fc12/disk-35c3e279.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6f39fa55c828/vmlinux-35c3e279.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e1e0501539e6/bzImage-35c3e279.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8983d6d4f7df556be565@syzkaller.appspotmail.com

=====================================================
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
6.8.0-syzkaller-05228-g35c3e2791756 #0 Not tainted
-----------------------------------------------------
rcu_preempt/16 [HC0[0]:SC0[2]:HE0:SE0] is trying to acquire:
ffff888021c65020 (&htab->buckets[i].lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff888021c65020 (&htab->buckets[i].lock){+...}-{2:2}, at: sock_hash_delete_elem+0xb0/0x300 net/core/sock_map.c:939

and this task is already holding:
ffff8880b952a758
 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x112/0x240 kernel/time/timer.c:1051
which would create a new lock dependency:
 (&base->lock){-.-.}-{2:2} -> (
&htab->buckets[i].lock){+...}-{2:2}

but this new dependency connects a HARDIRQ-irq-safe lock:
 (&base->lock){-.-.}-{2:2}

... which became HARDIRQ-irq-safe at:
  lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
  lock_timer_base+0x112/0x240 kernel/time/timer.c:1051
  add_timer_on+0x1e5/0x5c0 kernel/time/timer.c:1366
  handle_irq_event_percpu kernel/irq/handle.c:195 [inline]
  handle_irq_event+0xad/0x1f0 kernel/irq/handle.c:210
  handle_level_irq+0x3c5/0x6e0 kernel/irq/chip.c:648
  generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
  handle_irq arch/x86/kernel/irq.c:238 [inline]
  __common_interrupt+0x13a/0x230 arch/x86/kernel/irq.c:257
  common_interrupt+0xa5/0xd0 arch/x86/kernel/irq.c:247
  asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
  __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
  _raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194
  __setup_irq+0x1277/0x1cf0 kernel/irq/manage.c:1818
  request_threaded_irq+0x2ab/0x380 kernel/irq/manage.c:2202
  request_irq include/linux/interrupt.h:168 [inline]
  setup_default_timer_irq+0x25/0x60 arch/x86/kernel/time.c:70
  x86_late_time_init+0x66/0xc0 arch/x86/kernel/time.c:94
  start_kernel+0x3f3/0x500 init/main.c:1039
  x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509
  x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490
  common_startup_64+0x13e/0x147

to a HARDIRQ-irq-unsafe lock:
 (&htab->buckets[i].lock){+...}-{2:2}

... which became HARDIRQ-irq-unsafe at:
...
  lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
  __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
  _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
  spin_lock_bh include/linux/spinlock.h:356 [inline]
  sock_hash_free+0x164/0x820 net/core/sock_map.c:1154
  bpf_map_free_deferred+0xe6/0x110 kernel/bpf/syscall.c:734
  process_one_work kernel/workqueue.c:3254 [inline]
  process_scheduled_works+0xa00/0x1770 kernel/workqueue.c:3335
  worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
  kthread+0x2f0/0x390 kernel/kthread.c:388
  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

other info that might help us debug this:

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&htab->buckets[i].lock
);
                               local_irq_disable();
                               lock(&base->lock);
                               lock(&htab->buckets[i].lock
);
  <Interrupt>
    lock(&base->lock);

 *** DEADLOCK ***

2 locks held by rcu_preempt/16:
 #0: 
ffff8880b952a758
 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x112/0x240 kernel/time/timer.c:1051
 #1: ffffffff8e131920
 (rcu_read_lock
){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2380 [inline]
){....}-{1:2}, at: bpf_trace_run2+0x114/0x420 kernel/trace/bpf_trace.c:2420

the dependencies between HARDIRQ-irq-safe lock and the holding lock:
-> (&base->lock){-.-.}-{2:2} {
   IN-HARDIRQ-W at:
                    lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
                    lock_timer_base+0x112/0x240 kernel/time/timer.c:1051
                    add_timer_on+0x1e5/0x5c0 kernel/time/timer.c:1366
                    handle_irq_event_percpu kernel/irq/handle.c:195 [inline]
                    handle_irq_event+0xad/0x1f0 kernel/irq/handle.c:210
                    handle_level_irq+0x3c5/0x6e0 kernel/irq/chip.c:648
                    generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
                    handle_irq arch/x86/kernel/irq.c:238 [inline]
                    __common_interrupt+0x13a/0x230 arch/x86/kernel/irq.c:257
                    common_interrupt+0xa5/0xd0 arch/x86/kernel/irq.c:247
                    asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
                    __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
                    _raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194
                    __setup_irq+0x1277/0x1cf0 kernel/irq/manage.c:1818
                    request_threaded_irq+0x2ab/0x380 kernel/irq/manage.c:2202
                    request_irq include/linux/interrupt.h:168 [inline]
                    setup_default_timer_irq+0x25/0x60 arch/x86/kernel/time.c:70
                    x86_late_time_init+0x66/0xc0 arch/x86/kernel/time.c:94
                    start_kernel+0x3f3/0x500 init/main.c:1039
                    x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509
                    x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490
                    common_startup_64+0x13e/0x147
   IN-SOFTIRQ-W at:
                    lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
                    __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
                    _raw_spin_lock_irq+0xd3/0x120 kernel/locking/spinlock.c:170
                    __run_timer_base+0x103/0x8e0 kernel/time/timer.c:2418
                    run_timer_base kernel/time/timer.c:2428 [inline]
                    run_timer_softirq+0x67/0x170 kernel/time/timer.c:2436
                    __do_softirq+0x2be/0x943 kernel/softirq.c:554
                    invoke_softirq kernel/softirq.c:428 [inline]
                    __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633
                    irq_exit_rcu+0x9/0x30 kernel/softirq.c:645
                    common_interrupt+0xaa/0xd0 arch/x86/kernel/irq.c:247
                    asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
                    console_flush_all+0x9cd/0xec0
                    console_unlock+0x13b/0x4d0 kernel/printk/printk.c:3025
                    vprintk_emit+0x509/0x720 kernel/printk/printk.c:2292
                    _printk+0xd5/0x120 kernel/printk/printk.c:2317
                    cpu_select_mitigations+0x3c/0xa0 arch/x86/kernel/cpu/bugs.c:148
                    arch_cpu_finalize_init+0x20/0xa0 arch/x86/kernel/cpu/common.c:2325
                    start_kernel+0x402/0x500 init/main.c:1043
                    x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509
                    x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490
                    common_startup_64+0x13e/0x147
   INITIAL USE
 at:
                   lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
                   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                   _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
                   lock_timer_base+0x112/0x240 kernel/time/timer.c:1051
                   __mod_timer+0x1ca/0xeb0 kernel/time/timer.c:1132
                   queue_delayed_work_on+0x15a/0x260 kernel/workqueue.c:2595
                   queue_delayed_work include/linux/workqueue.h:620 [inline]
                   crng_reseed+0xe7/0x220 drivers/char/random.c:258
                   random_init+0x1a9/0x300 drivers/char/random.c:901
                   start_kernel+0x253/0x500 init/main.c:991
                   x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509
                   x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490
                   common_startup_64+0x13e/0x147
 }
 ... key      at: [<ffffffff945023c0>] init_timer_cpu.__key+0x0/0x20

the dependencies between the lock to be acquired
 and HARDIRQ-irq-unsafe lock:
->
 (&htab->buckets[i].lock
){+...}-{2:2} {
   HARDIRQ-ON-W at:
                    lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
                    __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                    _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
                    spin_lock_bh include/linux/spinlock.h:356 [inline]
                    sock_hash_free+0x164/0x820 net/core/sock_map.c:1154
                    bpf_map_free_deferred+0xe6/0x110 kernel/bpf/syscall.c:734
                    process_one_work kernel/workqueue.c:3254 [inline]
                    process_scheduled_works+0xa00/0x1770 kernel/workqueue.c:3335
                    worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
                    kthread+0x2f0/0x390 kernel/kthread.c:388
                    ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
   INITIAL USE
 at:
                   lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
                   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                   _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
                   spin_lock_bh include/linux/spinlock.h:356 [inline]
                   sock_hash_free+0x164/0x820 net/core/sock_map.c:1154
                   bpf_map_free_deferred+0xe6/0x110 kernel/bpf/syscall.c:734
                   process_one_work kernel/workqueue.c:3254 [inline]
                   process_scheduled_works+0xa00/0x1770 kernel/workqueue.c:3335
                   worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
                   kthread+0x2f0/0x390 kernel/kthread.c:388
                   ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
                   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
 }
 ... key      at: [<ffffffff94882300>] sock_hash_alloc.__key+0x0/0x20
 ... acquired at:
   lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
   _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
   spin_lock_bh include/linux/spinlock.h:356 [inline]
   sock_hash_delete_elem+0xb0/0x300 net/core/sock_map.c:939
   bpf_prog_2c29ac5cdc6b1842+0x42/0x46
   bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
   __bpf_prog_run include/linux/filter.h:657 [inline]
   bpf_prog_run include/linux/filter.h:664 [inline]
   __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
   bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
   trace_timer_start include/trace/events/timer.h:52 [inline]
   enqueue_timer+0x396/0x550 kernel/time/timer.c:663
   internal_add_timer kernel/time/timer.c:688 [inline]
   __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183
   schedule_timeout+0x1b9/0x310 kernel/time/timer.c:2571
   rcu_gp_fqs_loop+0x2df/0x1370 kernel/rcu/tree.c:1663
   rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:1862
   kthread+0x2f0/0x390 kernel/kthread.c:388
   ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243


stack backtrace:
CPU: 1 PID: 16 Comm: rcu_preempt Not tainted 6.8.0-syzkaller-05228-g35c3e2791756 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
 print_bad_irq_dependency kernel/locking/lockdep.c:2626 [inline]
 check_irq_usage kernel/locking/lockdep.c:2865 [inline]
 check_prev_add kernel/locking/lockdep.c:3138 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x4dc7/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
 _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 sock_hash_delete_elem+0xb0/0x300 net/core/sock_map.c:939
 bpf_prog_2c29ac5cdc6b1842+0x42/0x46
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
 bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
 trace_timer_start include/trace/events/timer.h:52 [inline]
 enqueue_timer+0x396/0x550 kernel/time/timer.c:663
 internal_add_timer kernel/time/timer.c:688 [inline]
 __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183
 schedule_timeout+0x1b9/0x310 kernel/time/timer.c:2571
 rcu_gp_fqs_loop+0x2df/0x1370 kernel/rcu/tree.c:1663
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:1862
 kthread+0x2f0/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
 </TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [syzbot] [batman?] [bpf?] possible deadlock in lock_timer_base
  2024-03-19 10:33 ` [syzbot] [batman?] [bpf?] " syzbot
@ 2024-03-19 13:19   ` Sven Eckelmann
  2024-03-19 13:31     ` Aleksandr Nogikh
  2024-03-23 22:46   ` Hillf Danton
  1 sibling, 1 reply; 7+ messages in thread
From: Sven Eckelmann @ 2024-03-19 13:19 UTC (permalink / raw)
  To: akpm, andrii, ast, b.a.t.m.a.n, bpf, christian, daniel, dvyukov,
	edumazet, elver, glider, hdanton, jakub, jannh, john.fastabend,
	kasan-dev, kuba, linux-kernel, linux-mm, mareklindner,
	mark.rutland, netdev, pabeni, shakeelb, syzkaller-bugs, syzbot

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On Tuesday, 19 March 2024 11:33:17 CET syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    35c3e2791756 Revert "net: Re-use and set mono_delivery_tim..
> git tree:       net
> console output: https://syzkaller.appspot.com/x/log.txt?x=10569181180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
> dashboard link: https://syzkaller.appspot.com/bug?extid=8983d6d4f7df556be565
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13d9fa4e180000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=137afac9180000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/26b55a26fc12/disk-35c3e279.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/6f39fa55c828/vmlinux-35c3e279.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/e1e0501539e6/bzImage-35c3e279.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+8983d6d4f7df556be565@syzkaller.appspotmail.com

Sorry, this is a little bit off-topic. But how does sysbot figure out the 
subsystems (like "[batman?]"). Because neither the reproducer nor the 
backtrace nor the console output mention anything batman-adv related.

Kind regards,
	Sven

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^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [syzbot] [batman?] [bpf?] possible deadlock in lock_timer_base
  2024-03-19 13:19   ` Sven Eckelmann
@ 2024-03-19 13:31     ` Aleksandr Nogikh
  0 siblings, 0 replies; 7+ messages in thread
From: Aleksandr Nogikh @ 2024-03-19 13:31 UTC (permalink / raw)
  To: Sven Eckelmann
  Cc: akpm, andrii, ast, b.a.t.m.a.n, bpf, christian, daniel, dvyukov,
	edumazet, elver, glider, hdanton, jakub, jannh, john.fastabend,
	kasan-dev, kuba, linux-kernel, linux-mm, mareklindner,
	mark.rutland, netdev, pabeni, shakeelb, syzkaller-bugs, syzbot

Hi Sven,

On Tue, Mar 19, 2024 at 2:19 PM Sven Eckelmann <sven@narfation.org> wrote:
>
> On Tuesday, 19 March 2024 11:33:17 CET syzbot wrote:
> > syzbot has found a reproducer for the following issue on:
> >
< ... >
>
> Sorry, this is a little bit off-topic. But how does sysbot figure out the
> subsystems (like "[batman?]"). Because neither the reproducer nor the
> backtrace nor the console output mention anything batman-adv related.

Syzbot looks at several crash reports to determine the bug subsystems
and in this case one of those crashes was pointing to
net/batman-adv/multicast.c:

https://syzkaller.appspot.com/text?tag=CrashReport&x=15afccb3280000

-- 
Aleksandr

>
> Kind regards,
>         Sven
>
> --

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [syzbot] [batman?] [bpf?] possible deadlock in lock_timer_base
  2024-03-19 10:33 ` [syzbot] [batman?] [bpf?] " syzbot
  2024-03-19 13:19   ` Sven Eckelmann
@ 2024-03-23 22:46   ` Hillf Danton
  2024-03-24  2:51     ` syzbot
  1 sibling, 1 reply; 7+ messages in thread
From: Hillf Danton @ 2024-03-23 22:46 UTC (permalink / raw)
  To: syzbot; +Cc: linux-kernel, syzkaller-bugs

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git  ea80e3ed09ab

--- x/net/core/sock_map.c
+++ y/net/core/sock_map.c
@@ -932,11 +932,12 @@ static long sock_hash_delete_elem(struct
 	struct bpf_shtab_bucket *bucket;
 	struct bpf_shtab_elem *elem;
 	int ret = -ENOENT;
+	unsigned long flags;
 
 	hash = sock_hash_bucket_hash(key, key_size);
 	bucket = sock_hash_select_bucket(htab, hash);
 
-	spin_lock_bh(&bucket->lock);
+	spin_lock_irqsave(&bucket->lock, flags);
 	elem = sock_hash_lookup_elem_raw(&bucket->head, hash, key, key_size);
 	if (elem) {
 		hlist_del_rcu(&elem->node);
@@ -944,7 +945,7 @@ static long sock_hash_delete_elem(struct
 		sock_hash_free_elem(htab, elem);
 		ret = 0;
 	}
-	spin_unlock_bh(&bucket->lock);
+	spin_unlock_irqrestore(&bucket->lock, flags);
 	return ret;
 }
 
@@ -1143,6 +1144,8 @@ static void sock_hash_free(struct bpf_ma
 	 */
 	synchronize_rcu();
 	for (i = 0; i < htab->buckets_num; i++) {
+		unsigned long flags;
+
 		bucket = sock_hash_select_bucket(htab, i);
 
 		/* We are racing with sock_hash_delete_from_link to
@@ -1151,11 +1154,11 @@ static void sock_hash_free(struct bpf_ma
 		 * exists, psock exists and holds a ref to socket. That
 		 * lets us to grab a socket ref too.
 		 */
-		spin_lock_bh(&bucket->lock);
+		spin_lock_irqsave(&bucket->lock, flags);
 		hlist_for_each_entry(elem, &bucket->head, node)
 			sock_hold(elem->sk);
 		hlist_move_list(&bucket->head, &unlink_list);
-		spin_unlock_bh(&bucket->lock);
+		spin_unlock_irqrestore(&bucket->lock, flags);
 
 		/* Process removed entries out of atomic context to
 		 * block for socket lock before deleting the psock's
--

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [syzbot] [batman?] [bpf?] possible deadlock in lock_timer_base
  2024-03-23 22:46   ` Hillf Danton
@ 2024-03-24  2:51     ` syzbot
  0 siblings, 0 replies; 7+ messages in thread
From: syzbot @ 2024-03-24  2:51 UTC (permalink / raw)
  To: hdanton, linux-kernel, syzkaller-bugs

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+8983d6d4f7df556be565@syzkaller.appspotmail.com

Tested on:

commit:         ea80e3ed net: ethernet: mtk_eth_soc: fix PPE hanging i..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12583185180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
dashboard link: https://syzkaller.appspot.com/bug?extid=8983d6d4f7df556be565
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12f9eaa5180000

Note: testing is done by a robot and is best-effort only.

^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2024-03-24  2:51 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-03  6:59 possible deadlock in lock_timer_base syzbot
     [not found] ` <20210103094904.14908-1-hdanton@sina.com>
2021-01-04 10:54   ` Marco Elver
2024-03-19 10:33 ` [syzbot] [batman?] [bpf?] " syzbot
2024-03-19 13:19   ` Sven Eckelmann
2024-03-19 13:31     ` Aleksandr Nogikh
2024-03-23 22:46   ` Hillf Danton
2024-03-24  2:51     ` syzbot

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