INFO: task hung in blk_mq_freeze_queue

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 12ef385f Merge 4.4.130 into android-4.4
git tree: android-4.4
console output: https://syzkaller.appspot.com/x/log.txt?x=14e67a47800000
kernel config: https://syzkaller.appspot.com/x/.config?x=845cfc0609aa801f
dashboard link: https://syzkaller.appspot.com/bug?extid=92af4d89882e0aee1b41
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=132dbae7800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=102b255b800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+92af4d...@syzkaller.appspotmail.com

INFO: task syz-executor980:3899 blocked for more than 120 seconds.
Not tainted 4.4.130-g12ef385 #28
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor980 D ffff8801d46dfa80 27392 3899 3897 0x00000000
ffff8801d46dfa80 0000000000000246 0000000000000296 0000000041b58ab3
ffffffff841e1200 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
ffff8801db21f4c0 ffff8801d861c800 ffff8800bb380000 0000000000000000
Call Trace:
[<ffffffff838b14da>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
[<ffffffff81da0780>] blk_mq_freeze_queue_wait+0x120/0x240 block/blk-mq.c:95
[<ffffffff81da8e7d>] blk_freeze_queue block/blk-mq.c:112 [inline]
[<ffffffff81da8e7d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:121
[<ffffffff8251aee2>] loop_switch drivers/block/loop.c:610 [inline]
[<ffffffff8251aee2>] loop_change_fd drivers/block/loop.c:696 [inline]
[<ffffffff8251aee2>] lo_ioctl+0x722/0x1ad0 drivers/block/loop.c:1361
[<ffffffff81db6ec8>] __blkdev_driver_ioctl block/ioctl.c:288 [inline]
[<ffffffff81db6ec8>] blkdev_ioctl+0x7b8/0x19c0 block/ioctl.c:584
[<ffffffff815d374e>] block_ioctl+0xde/0x120 fs/block_dev.c:1625
[<ffffffff8155953f>] vfs_ioctl fs/ioctl.c:43 [inline]
[<ffffffff8155953f>] file_ioctl fs/ioctl.c:470 [inline]
[<ffffffff8155953f>] do_vfs_ioctl+0x63f/0xf40 fs/ioctl.c:605
[<ffffffff81559ecf>] SYSC_ioctl fs/ioctl.c:622 [inline]
[<ffffffff81559ecf>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
[<ffffffff838bf525>] entry_SYSCALL_64_fastpath+0x22/0x9e
1 lock held by syz-executor980/3899:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff8251a84b>]
lo_ioctl+0x8b/0x1ad0 drivers/block/loop.c:1355
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 491 Comm: khungtaskd Not tainted 4.4.130-g12ef385 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8800bac44800 task.stack: ffff8800bb238000
RIP: 0010:[<ffffffff810bfd66>] [<ffffffff810bfd66>] native_apic_mem_write
arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810bfd66>] [<ffffffff810bfd66>]
__default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810bfd66>] [<ffffffff810bfd66>] _flat_send_IPI_mask
arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810bfd66>] [<ffffffff810bfd66>]
flat_send_IPI_mask+0xf6/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bb23fcc8 EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb23fcf0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f7a0
FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5e200cd000 CR3: 00000000b64a4000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffffffff8446f7a0 ffffffff84a189a0 0000000000000007 fffffbfff0942be4
0000000000000040 ffff8800bb23fd10 ffffffff810b5d21 ffffffff83c0b0a0
0000000000000003 ffff8800bb23fd68 ffffffff81e18d03 ffffffff8140daaf
Call Trace:
[<ffffffff810b5d21>] nmi_raise_cpu_backtrace+0x61/0x80
arch/x86/kernel/apic/hw_nmi.c:33
[<ffffffff81e18d03>] nmi_trigger_all_cpu_backtrace.cold.4+0x70/0xad
lib/nmi_backtrace.c:85
[<ffffffff810b5dc4>] arch_trigger_all_cpu_backtrace+0x14/0x20
arch/x86/kernel/apic/hw_nmi.c:38
[<ffffffff8141a199>] trigger_all_cpu_backtrace include/linux/nmi.h:44
[inline]
[<ffffffff8141a199>] check_hung_task kernel/hung_task.c:125 [inline]
[<ffffffff8141a199>] check_hung_uninterruptible_tasks
kernel/hung_task.c:182 [inline]
[<ffffffff8141a199>] watchdog.cold.1+0xd3/0xee kernel/hung_task.c:238
[<ffffffff81190768>] kthread+0x268/0x300 kernel/kthread.c:211
[<ffffffff838bf955>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
Code: b3 5f ff f6 c4 10 75 e2 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89
f2 09 da 80 cf 04 41 83 fe 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00
02 00 00 75 1a 4c 89 e7 57 9d 0f 1f 44 00 00 e8 a2
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.130-g12ef385 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8801d9a41800 task.stack: ffff8801d9a50000
RIP: 0010:[<ffffffff810cc306>] [<ffffffff810cc306>]
native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffff8801d9a57da0 EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffffff84a05a68 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801d9a420dc
RBP: ffff8801d9a57da0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: fffffbfff074890c R15: ffffffff84a05a68
FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000c2c000 CR3: 00000001c8ca4000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffff8801d9a57dd8 ffffffff81025da5 ffff8801d9a58000 0000000000000000
0000000000000000 fffffbfff074890c ffffffff84a05a68 ffff8801d9a57de8
ffffffff810272f0 ffff8801d9a57e00 ffffffff8121b9e7 dffffc0000000000
Call Trace:
[<ffffffff81025da5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117
[inline]
[<ffffffff81025da5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
[<ffffffff810272f0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:281
[<ffffffff8121b9e7>] default_idle_call+0x57/0x70 kernel/sched/idle.c:93
[<ffffffff8121c18f>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
[<ffffffff8121c18f>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
[<ffffffff8121c18f>] cpu_startup_entry+0x6af/0x780 kernel/sched/idle.c:301
[<ffffffff810aa174>] start_secondary+0x324/0x400
arch/x86/kernel/smpboot.c:242
Code: 00 00 00 00 00 55 48 89 e5 fa 5d c3 66 0f 1f 84 00 00 00 00 00 55 48
89 e5 fb 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb f4 <5d> c3 0f 1f
84 00 00 00 00 00 55 48 89 e5 f4 5d c3 66 0f 1f 84


---
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[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 2bcbbd5b Merge 4.9.97 into android-4.9
git tree: android-4.9
console output: https://syzkaller.appspot.com/x/log.txt?x=1740dee7800000
kernel config: https://syzkaller.appspot.com/x/.config?x=1e52aa51291e98a6
dashboard link: https://syzkaller.appspot.com/bug?extid=8c016494415eba14e1f2

compiler: gcc (GCC) 8.0.1 20180413 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=166946e7800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13858097800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:

Reported-by: syzbot+8c0164...@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: crng init done
INFO: task syz-executor061:3863 blocked for more than 120 seconds.
Not tainted 4.9.97-g2bcbbd5 #14

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor061 D27176 3863 3861 0x00000000
ffff8801d8589800 0000000000000000 ffff8801d97464c0 ffffffff84629800
ffff8801db221b98 ffff8801d86a79f0 ffffffff839e375d 0000000000000002
0000000041b58ab3 ffffffff843b8763 00ffffff8121f1e0 ffff8801db222468
Call Trace:
[<ffffffff839e4d5f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
[<ffffffff81e3e264>] blk_mq_freeze_queue_wait+0x114/0x230 block/blk-mq.c:75
[<ffffffff81e4755d>] blk_freeze_queue block/blk-mq.c:92 [inline]
[<ffffffff81e4755d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:101
[<ffffffff825c7892>] loop_switch drivers/block/loop.c:599 [inline]
[<ffffffff825c7892>] loop_change_fd drivers/block/loop.c:685 [inline]
[<ffffffff825c7892>] lo_ioctl+0x722/0x1aa0 drivers/block/loop.c:1350
[<ffffffff81e54766>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
[<ffffffff81e54766>] blkdev_ioctl+0x7b6/0x1a70 block/ioctl.c:590
[<ffffffff8163032e>] block_ioctl+0xde/0x120 fs/block_dev.c:1688
[<ffffffff815b051c>] vfs_ioctl fs/ioctl.c:43 [inline]
[<ffffffff815b051c>] file_ioctl fs/ioctl.c:493 [inline]
[<ffffffff815b051c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
[<ffffffff815b159f>] SYSC_ioctl fs/ioctl.c:694 [inline]
[<ffffffff815b159f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839f4653>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/518:
#0: (rcu_read_lock){......}, at: [<ffffffff813646ec>]
check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
#0: (rcu_read_lock){......}, at: [<ffffffff813646ec>]
watchdog+0x11c/0xa20 kernel/hung_task.c:239
#1: (tasklist_lock){.+.+..}, at: [<ffffffff81423ce0>]
debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3780:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f2802>]
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211c8a2>]
n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor061/3863:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c71fb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

=============================================

NMI backtrace for cpu 0

CPU: 0 PID: 518 Comm: khungtaskd Not tainted 4.9.97-g2bcbbd5 #14

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011

ffff8801d9157d08 ffffffff81eb0b69 0000000000000000 0000000000000000
0000000000000000 0000000000000001 ffffffff810b7d60 ffff8801d9157d40
ffffffff81ebbe97 0000000000000000 0000000000000000 0000000000000003
Call Trace:
[<ffffffff81eb0b69>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81eb0b69>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff81ebbe97>] nmi_cpu_backtrace.cold.2+0x48/0x87
lib/nmi_backtrace.c:99
[<ffffffff81ebbe2a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f
lib/nmi_backtrace.c:60
[<ffffffff810b7e64>] arch_trigger_cpumask_backtrace+0x14/0x20
arch/x86/kernel/apic/hw_nmi.c:37
[<ffffffff81364c84>] trigger_all_cpu_backtrace include/linux/nmi.h:58
[inline]
[<ffffffff81364c84>] check_hung_task kernel/hung_task.c:125 [inline]
[<ffffffff81364c84>] check_hung_uninterruptible_tasks
kernel/hung_task.c:182 [inline]
[<ffffffff81364c84>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
[<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
[<ffffffff839f481c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff839f3266