On Thu, 04 Feb 2016 20:37:13 +0100, Dmitry Vyukov wrote:
Hello,
The following program hangs machine: https://gist.githubusercontent.com/dvyukov/1c9eeb67414a9e7c5e52/raw/127b660c...
BUG: spinlock lockup suspected on CPU#2, a.out/7470 lock: 0xffff880036a9ef50, .magic: dead4ead, .owner: a.out/7466, .owner_cpu: 3 CPU: 2 PID: 7470 Comm: a.out Not tainted 4.5.0-rc2+ #319 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 00000000ffffffff ffff88005f5ff660 ffffffff82be30ad ffff880036a9ef50 ffff88005d3d5f00 ffff88005d0b4740 ffff88005f5ff698 ffffffff8146768d ffffffff85241dce ffff880000000000 ffff880036a9ef50 ffff880036a9ef60 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffff82be30ad>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [<ffffffff8146768d>] spin_dump+0x14d/0x280 kernel/locking/spinlock_debug.c:67 [< inline >] __spin_lock_debug kernel/locking/spinlock_debug.c:117 [<ffffffff814679ad>] do_raw_spin_lock+0x15d/0x2b0 kernel/locking/spinlock_debug.c:137 [< inline >] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [<ffffffff8665ea57>] _raw_spin_lock_irqsave+0xa7/0xd0 kernel/locking/spinlock.c:159 [<ffffffff85241dce>] snd_timer_start+0x10e/0x2b0 sound/core/timer.c:491 [< inline >] seq_timer_start sound/core/seq/seq_timer.c:393 [<ffffffff852bf860>] snd_seq_timer_start+0x1a0/0x2b0 sound/core/seq/seq_timer.c:405 [< inline >] snd_seq_queue_process_event sound/core/seq/seq_queue.c:687 [<ffffffff852ba514>] snd_seq_control_queue+0x304/0x8b0 sound/core/seq/seq_queue.c:748 [<ffffffff852c01b5>] event_input_timer+0x25/0x30 sound/core/seq/seq_system.c:118 [<ffffffff852b2de4>] snd_seq_deliver_single_event.constprop.11+0x3f4/0x740 sound/core/seq/seq_clientmgr.c:634 [<ffffffff852b3248>] snd_seq_deliver_event+0x118/0x800 sound/core/seq/seq_clientmgr.c:831 [<ffffffff852b4636>] snd_seq_kernel_client_dispatch+0x126/0x170 sound/core/seq/seq_clientmgr.c:2404 [<ffffffff852c92eb>] send_timer_event.isra.0+0x10b/0x150 sound/core/seq/oss/seq_oss_timer.c:153 [<ffffffff852c981a>] snd_seq_oss_timer_start+0x1ca/0x310 sound/core/seq/oss/seq_oss_timer.c:174 [<ffffffff852c9c04>] snd_seq_oss_process_timer_event+0x2a4/0x340 sound/core/seq/oss/seq_oss_timer.c:106 [< inline >] insert_queue sound/core/seq/oss/seq_oss_rw.c:170 [<ffffffff852cf7ab>] snd_seq_oss_write+0x20b/0x810 sound/core/seq/oss/seq_oss_rw.c:148 [<ffffffff852c74f9>] odev_write+0x59/0xa0 sound/core/seq/oss/seq_oss.c:179 [<ffffffff817bacd3>] __vfs_write+0x113/0x4b0 fs/read_write.c:528 [<ffffffff817bc797>] vfs_write+0x167/0x4a0 fs/read_write.c:577 [< inline >] SYSC_write fs/read_write.c:624 [<ffffffff817bfa81>] SyS_write+0x111/0x220 fs/read_write.c:616 [<ffffffff8665f0b6>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 Sending NMI to all CPUs: NMI backtrace for cpu 0 CPU: 0 PID: 7473 Comm: a.out Not tainted 4.5.0-rc2+ #319 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88003376df00 ti: ffff880032440000 task.ti: ffff880032440000 RIP: 0010:[<ffffffff82c103a7>] [<ffffffff82c103a7>] delay_tsc+0x27/0x70 RSP: 0018:ffff8800324479f8 EFLAGS: 00000006 RAX: 00000000a0066ab3 RBX: ffff880036a9ef50 RCX: 000000000000001e RDX: 0000000000000100 RSI: 00000100a0066a95 RDI: 0000000000000001 RBP: ffff8800324479f8 R08: 0000000000000000 R09: 0000000000000001 R10: ffff88003376df00 R11: ffff880036a9ef68 R12: ffff880036a9ef60 R13: 000000009a9d2d40 R14: ffff880036a9ef58 R15: 0000000099db9d6d FS: 00007f94a370e700(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 000000c82010e120 CR3: 000000003334f000 CR4: 00000000000006f0 Stack: ffff880032447a08 ffffffff82c102ea ffff880032447a40 ffffffff81467999 ffff880036a9ef50 ffff880036a9ee20 0000000000000282 ffff880035d8ab70 0000000000000000 ffff880032447a60 ffffffff8665dfbb ffffffff8523dd64 Call Trace: [<ffffffff82c102ea>] __delay+0xa/0x10 arch/x86/lib/delay.c:153 [< inline >] __spin_lock_debug kernel/locking/spinlock_debug.c:114 [<ffffffff81467999>] do_raw_spin_lock+0x149/0x2b0 kernel/locking/spinlock_debug.c:137 [< inline >] __raw_spin_lock include/linux/spinlock_api_smp.h:145 [<ffffffff8665dfbb>] _raw_spin_lock+0x3b/0x50 kernel/locking/spinlock.c:151 [< inline >] spin_lock include/linux/spinlock.h:302 [<ffffffff8523dd64>] snd_timer_start_slave+0xd4/0x200 sound/core/timer.c:460 [<ffffffff85241880>] snd_timer_continue+0x200/0x290 sound/core/timer.c:598 [< inline >] snd_timer_user_continue sound/core/timer.c:1822 [< inline >] __snd_timer_user_ioctl sound/core/timer.c:1889 [<ffffffff85246a9d>] snd_timer_user_ioctl+0xe1d/0x25f0 sound/core/timer.c:1904 [< inline >] vfs_ioctl fs/ioctl.c:43 [<ffffffff817faf7c>] do_vfs_ioctl+0x18c/0xfb0 fs/ioctl.c:674 [< inline >] SYSC_ioctl fs/ioctl.c:689 [<ffffffff817fbe2f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:680 [<ffffffff8665f0b6>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 Code: 00 00 00 00 55 65 ff 05 c8 4a 40 7d 48 89 e5 65 44 8b 05 8d 2d 40 7d 0f ae e8 0f 31 48 c1 e2 20 48 89 d6 48 09 c6 0f ae e8 0f 31 <48> c1 e2 20 48 09 d0 48 89 c1 48 29 f1 48 39 f9 73 27 65 ff 0d NMI backtrace for cpu 1 CPU: 1 PID: 7421 Comm: stress Not tainted 4.5.0-rc2+ #319 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88003330df00 ti: ffff880032230000 task.ti: ffff880032230000 RIP: 0010:[<ffffffff82c103a7>] [<ffffffff82c103a7>] delay_tsc+0x27/0x70 RSP: 0018:ffff88003ed07c80 EFLAGS: 00000006 RAX: 00000000a0066d38 RBX: ffff880036a9ef50 RCX: 000000000000001e RDX: 0000000000000100 RSI: 00000100a0066d0f RDI: 0000000000000001 RBP: ffff88003ed07c80 R08: 0000000000000001 R09: 0000000000000001 R10: ffff88003330df00 R11: ffff880036a9ef68 R12: ffff880036a9ef60 R13: 000000009a9d2d40 R14: ffff880036a9ef58 R15: 000000009a82fe90 FS: 000000c820127700(0000) GS:ffff88003ed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c8201004e0 CR3: 0000000032076000 CR4: 00000000000006e0 Stack: ffff88003ed07c90 ffffffff82c102ea ffff88003ed07cc8 ffffffff81467999 ffff880036a9ef50 0000000000000082 ffff880036a9ee20 00000000000f4240 ffff880032795068 ffff88003ed07cf0 ffffffff8665ea57 ffffffff85242019 Call Trace: d [<ffffffff82c102ea>] __delay+0xa/0x10 arch/x86/lib/delay.c:153 [< inline >] __spin_lock_debug kernel/locking/spinlock_debug.c:114 [<ffffffff81467999>] do_raw_spin_lock+0x149/0x2b0 kernel/locking/spinlock_debug.c:137 [< inline >] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [<ffffffff8665ea57>] _raw_spin_lock_irqsave+0xa7/0xd0 kernel/locking/spinlock.c:159 [<ffffffff85242019>] snd_timer_interrupt+0xa9/0xc80 sound/core/timer.c:718 [<ffffffff85248cb9>] snd_hrtimer_callback+0x169/0x230 sound/core/hrtimer.c:54 [< inline >] __run_hrtimer kernel/time/hrtimer.c:1248 [<ffffffff814b7dc3>] __hrtimer_run_queues+0x363/0xc20 kernel/time/hrtimer.c:1312 [<ffffffff814b9de2>] hrtimer_interrupt+0x182/0x430 kernel/time/hrtimer.c:1346 [<ffffffff8124e1d2>] local_apic_timer_interrupt+0x72/0xe0 arch/x86/kernel/apic/apic.c:907 [<ffffffff812516f9>] smp_apic_timer_interrupt+0x79/0xa0 arch/x86/kernel/apic/apic.c:931 [<ffffffff8665feac>] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:520 [<ffffffff817ab804>] create_object+0x34/0x2d0 mm/kmemleak.c:546 [<ffffffff86641fb3>] kmemleak_alloc+0x63/0xa0 mm/kmemleak.c:916 [< inline >] kmemleak_alloc_recursive include/linux/kmemleak.h:47 [< inline >] slab_post_alloc_hook mm/slub.c:1337 [< inline >] slab_alloc_node mm/slub.c:2596 [< inline >] slab_alloc mm/slub.c:2604 [<ffffffff81760843>] kmem_cache_alloc+0x153/0x2e0 mm/slub.c:2609 [<ffffffff8181b1b5>] dup_fd+0x85/0xa90 fs/file.c:298 [< inline >] copy_files kernel/fork.c:1033 [<ffffffff8134efed>] copy_process.part.35+0x188d/0x57a0 kernel/fork.c:1436 [< inline >] copy_process kernel/fork.c:1274 [<ffffffff8135322c>] _do_fork+0x1bc/0xcb0 kernel/fork.c:1723 [< inline >] SYSC_clone kernel/fork.c:1832 [<ffffffff81353df7>] SyS_clone+0x37/0x50 kernel/fork.c:1826 [<ffffffff8665f0b6>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 Code: 00 00 00 00 55 65 ff 05 c8 4a 40 7d 48 89 e5 65 44 8b 05 8d 2d 40 7d 0f ae e8 0f 31 48 c1 e2 20 48 89 d6 48 09 c6 0f ae e8 0f 31 <48> c1 e2 20 48 09 d0 48 89 c1 48 29 f1 48 39 f9 73 27 65 ff 0d NMI backtrace for cpu 2 CPU: 2 PID: 7470 Comm: a.out Not tainted 4.5.0-rc2+ #319 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88005d0b4740 ti: ffff88005f5f8000 task.ti: ffff88005f5f8000 RIP: 0010:[<ffffffff81262066>] [<ffffffff81262066>] flat_send_IPI_mask+0x156/0x290 RSP: 0018:ffff88005f5ff5d0 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000 RDX: 0000000000000c00 RSI: 0000000000000002 RDI: ffffffffff5fc300 RBP: ffff88005f5ff5f8 R08: 0000000000000001 R09: 0000000000000000 R10: fffffbfff11c14aa R11: 1ffffffff13552ed R12: 0000000000000082 BUG: spinlock lockup suspected on CPU#1, stress/7421 lock: 0xffff880036a9ef50, .magic: dead4ead, .owner: a.out/7466, .owner_cpu: 3 CPU: 1 PID: 7421 Comm: stress Not tainted 4.5.0-rc2+ #319 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 00000000ffffffff ffff88003ed07c58 ffffffff82be30ad ffff880036a9ef50 ffff88005d3d5f00 ffff88003330df00 ffff88003ed07c90 ffffffff8146768d ffffffff85242019 0000000000000000 ffff880036a9ef50 ffff880036a9ef60 Call Trace: <IRQ> [< inline >] __dump_stack lib/dump_stack.c:15 <IRQ> [<ffffffff82be30ad>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [<ffffffff8146768d>] spin_dump+0x14d/0x280 kernel/locking/spinlock_debug.c:67 [< inline >] __spin_lock_debug kernel/locking/spinlock_debug.c:117 [<ffffffff814679ad>] do_raw_spin_lock+0x15d/0x2b0 kernel/locking/spinlock_debug.c:137 [< inline >] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [<ffffffff8665ea57>] _raw_spin_lock_irqsave+0xa7/0xd0 kernel/locking/spinlock.c:159 [<ffffffff85242019>] snd_timer_interrupt+0xa9/0xc80 sound/core/timer.c:718 [<ffffffff85248cb9>] snd_hrtimer_callback+0x169/0x230 sound/core/hrtimer.c:54 [< inline >] __run_hrtimer kernel/time/hrtimer.c:1248 [<ffffffff814b7dc3>] __hrtimer_run_queues+0x363/0xc20 kernel/time/hrtimer.c:1312 [<ffffffff814b9de2>] hrtimer_interrupt+0x182/0x430 kernel/time/hrtimer.c:1346 [<ffffffff8124e1d2>] local_apic_timer_interrupt+0x72/0xe0 arch/x86/kernel/apic/apic.c:907 [<ffffffff812516f9>] smp_apic_timer_interrupt+0x79/0xa0 arch/x86/kernel/apic/apic.c:931 [<ffffffff8665feac>] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:520 [<ffffffff817ab804>] create_object+0x34/0x2d0 mm/kmemleak.c:546 [<ffffffff86641fb3>] kmemleak_alloc+0x63/0xa0 mm/kmemleak.c:916 [< inline >] kmemleak_alloc_recursive include/linux/kmemleak.h:47 [< inline >] slab_post_alloc_hook mm/slub.c:1337 [< inline >] slab_alloc_node mm/slub.c:2596 [< inline >] slab_alloc mm/slub.c:2604 [<ffffffff81760843>] kmem_cache_alloc+0x153/0x2e0 mm/slub.c:2609 [<ffffffff8181b1b5>] dup_fd+0x85/0xa90 fs/file.c:298 [< inline >] copy_files kernel/fork.c:1033 [<ffffffff8134efed>] copy_process.part.35+0x188d/0x57a0 kernel/fork.c:1436 [< inline >] copy_process kernel/fork.c:1274 [<ffffffff8135322c>] _do_fork+0x1bc/0xcb0 kernel/fork.c:1723 [< inline >] SYSC_clone kernel/fork.c:1832 [<ffffffff81353df7>] SyS_clone+0x37/0x50 kernel/fork.c:1826 [<ffffffff8665f0b6>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 R13: 000000000f000000 R14: ffffffff87b00c80 R15: 0000000000000002 FS: 00007fcabc427700(0000) GS:ffff88006d600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000020028073 CR3: 000000005c829000 CR4: 00000000000006e0 Stack: ffffffff87b00c80 ffffffff888be0a0 0000000000000007 fffffbfff111761c ffff88006d71a540 ffff88005f5ff618 ffffffff81257bfe ffffffff86ac7020 dffffc0000000000 ffff88005f5ff688 ffffffff82bee6ac ffffffff811aa610 Call Trace: [<ffffffff81257bfe>] nmi_raise_cpu_backtrace+0x5e/0x80 arch/x86/kernel/apic/hw_nmi.c:33 [<ffffffff82bee6ac>] nmi_trigger_all_cpu_backtrace+0x54c/0x5f0 lib/nmi_backtrace.c:85 [<ffffffff81257c54>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 [< inline >] trigger_all_cpu_backtrace include/linux/nmi.h:41 [< inline >] __spin_lock_debug kernel/locking/spinlock_debug.c:119 [<ffffffff814679b7>] do_raw_spin_lock+0x167/0x2b0 kernel/locking/spinlock_debug.c:137 [< inline >] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [<ffffffff8665ea57>] _raw_spin_lock_irqsave+0xa7/0xd0 kernel/locking/spinlock.c:159 [<ffffffff85241dce>] snd_timer_start+0x10e/0x2b0 sound/core/timer.c:491 [< inline >] seq_timer_start sound/core/seq/seq_timer.c:393 [<ffffffff852bf860>] snd_seq_timer_start+0x1a0/0x2b0 sound/core/seq/seq_timer.c:405 [< inline >] snd_seq_queue_process_event sound/core/seq/seq_queue.c:687 [<ffffffff852ba514>] snd_seq_control_queue+0x304/0x8b0 sound/core/seq/seq_queue.c:748 [<ffffffff852c01b5>] event_input_timer+0x25/0x30 sound/core/seq/seq_system.c:118 [<ffffffff852b2de4>] snd_seq_deliver_single_event.constprop.11+0x3f4/0x740 sound/core/seq/seq_clientmgr.c:634 [<ffffffff852b3248>] snd_seq_deliver_event+0x118/0x800 sound/core/seq/seq_clientmgr.c:831
On commit b37a05c083c85c2657dca9bbe1f5d79dccf756d5 + latest Takashi fixes.
This took really long time to finally figure out what goes wrong. Despite it showing OSS sequencer, the real culprit of this lockup was a typo: a wrong pointer was passed in the loop.
@@ -422,7 +422,7 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event) spin_lock_irqsave(&timer->lock, flags); list_for_each_entry(ts, &ti->slave_active_head, active_list) if (ts->ccallback) - ts->ccallback(ti, event + 100, &tstamp, resolution); + ts->ccallback(ts, event + 100, &tstamp, resolution); spin_unlock_irqrestore(&timer->lock, flags);
The proper patch is found in the first attachment.
However, this alone isn't enough. I still got a list corruption even after that fix. Chasing this also took long time, and it resulted in yet another trivial patch, as found in the second attachment. It's basically a missing spinlock for a slave timer at stopping it.
@@ -518,9 +518,13 @@ static int _snd_timer_stop(struct snd_timer_instance *timeri, int event) spin_unlock_irqrestore(&slave_active_lock, flags); return -EBUSY; } + if (timeri->timer) + spin_lock(&timeri->timer->lock); timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING; list_del_init(&timeri->ack_list); list_del_init(&timeri->active_list); + if (timeri->timer) + spin_unlock(&timeri->timer->lock); spin_unlock_irqrestore(&slave_active_lock, flags); goto __end; }
Could you try these two patches below? These cured the test case on my local machine, at least. If it's not enough, I have yet more patches to try, but these are the minimally needed changes I figured out.
thanks,
Takashi