INFO: task hung in lo_ioctl

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b11964ad ANDROID: cuttlefish: enable CONFIG_INET_UDP_DIAG=y
git tree: android-4.14
console output: https://syzkaller.appspot.com/x/log.txt?x=14d39723200000
kernel config: https://syzkaller.appspot.com/x/.config?x=322dd7397c84f390
dashboard link: https://syzkaller.appspot.com/bug?extid=94194c9c1942daee32f4
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120c6dad200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+94194c...@syzkaller.appspotmail.com

random: cc1: uninitialized urandom read (8 bytes read)
audit: type=1400 audit(1552161453.819:9): avc: denied { map } for
pid=1946 comm="syz-execprog" path="/root/syzkaller-shm673589165" dev="sda1"
ino=16482 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:file_t:s0 tclass=file permissive=1
INFO: task syz-executor.2:1962 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D25144 1962 1 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
lo_ioctl+0x83/0x1970 drivers/block/loop.c:1405
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x4d9/0x1810 block/ioctl.c:594
block_ioctl+0xd9/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
INFO: task syz-executor.4:1970 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D25640 1970 1 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
lo_open+0x19/0xb0 drivers/block/loop.c:1624
__blkdev_get+0x267/0xf90 fs/block_dev.c:1472
blkdev_get+0x97/0x8b0 fs/block_dev.c:1612
blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
do_dentry_open+0x41b/0xd60 fs/open.c:764
vfs_open+0x105/0x230 fs/open.c:878
do_last fs/namei.c:3455 [inline]
path_openat+0xb6b/0x2b70 fs/namei.c:3597
do_filp_open+0x1a1/0x280 fs/namei.c:3631
do_sys_open+0x2ca/0x590 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
INFO: task syz-executor.5:1972 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D25640 1972 1 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
lo_open+0x19/0xb0 drivers/block/loop.c:1624
__blkdev_get+0x267/0xf90 fs/block_dev.c:1472
blkdev_get+0x97/0x8b0 fs/block_dev.c:1612
blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
do_dentry_open+0x41b/0xd60 fs/open.c:764
vfs_open+0x105/0x230 fs/open.c:878
do_last fs/namei.c:3455 [inline]
path_openat+0xb6b/0x2b70 fs/namei.c:3597
do_filp_open+0x1a1/0x280 fs/namei.c:3631
do_sys_open+0x2ca/0x590 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
INFO: task syz-executor.0:1975 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D25640 1975 1 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
lo_open+0x19/0xb0 drivers/block/loop.c:1624
__blkdev_get+0x963/0xf90 fs/block_dev.c:1537
blkdev_get+0x97/0x8b0 fs/block_dev.c:1612
blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
do_dentry_open+0x41b/0xd60 fs/open.c:764
vfs_open+0x105/0x230 fs/open.c:878
do_last fs/namei.c:3455 [inline]
path_openat+0xb6b/0x2b70 fs/namei.c:3597
do_filp_open+0x1a1/0x280 fs/namei.c:3631
do_sys_open+0x2ca/0x590 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
INFO: task syz-executor.1:1978 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1 D25560 1978 1 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
lo_open+0x19/0xb0 drivers/block/loop.c:1624
__blkdev_get+0x267/0xf90 fs/block_dev.c:1472
blkdev_get+0x97/0x8b0 fs/block_dev.c:1612
blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
do_dentry_open+0x41b/0xd60 fs/open.c:764
vfs_open+0x105/0x230 fs/open.c:878
do_last fs/namei.c:3455 [inline]
path_openat+0xb6b/0x2b70 fs/namei.c:3597
do_filp_open+0x1a1/0x280 fs/namei.c:3631
do_sys_open+0x2ca/0x590 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
INFO: task syz-executor.3:3042 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D28688 3042 1968 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
loop_reread_partitions+0x72/0x80 drivers/block/loop.c:615
loop_set_status+0xbff/0x11f0 drivers/block/loop.c:1184
INFO: task blkid:3043 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid D28664 3043 2920 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
__lo_release drivers/block/loop.c:1644 [inline]
lo_release+0x78/0x190 drivers/block/loop.c:1668
__blkdev_put+0x518/0x6d0 fs/block_dev.c:1791
blkdev_close+0x86/0xb0 fs/block_dev.c:1863
__fput+0x25e/0x700 fs/file_table.c:210
task_work_run+0x118/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x13b/0x160 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:267 [inline]
do_syscall_64+0x372/0x4b0 arch/x86/entry/common.c:294
INFO: task blkid:3045 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid D29344 3045 308 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
lo_ioctl+0x83/0x1970 drivers/block/loop.c:1405
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x4d9/0x1810 block/ioctl.c:594
block_ioctl+0xd9/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
INFO: task blkid:3048 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid D27232 3048 2926 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
blkdev_get+0x97/0x8b0 fs/block_dev.c:1612
blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
do_dentry_open+0x41b/0xd60 fs/open.c:764
vfs_open+0x105/0x230 fs/open.c:878
do_last fs/namei.c:3455 [inline]
path_openat+0xb6b/0x2b70 fs/namei.c:3597
do_filp_open+0x1a1/0x280 fs/namei.c:3631
do_sys_open+0x2ca/0x590 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
INFO: task blkid:3052 blocked for more than 140 seconds.
Not tainted 4.14.105+ #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid D29264 3052 2919 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3492
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
blkdev_get+0x97/0x8b0 fs/block_dev.c:1612
blkdev_open+0x1cc/0x250 fs/block_dev.c:1770
do_dentry_open+0x41b/0xd60 fs/open.c:764
vfs_open+0x105/0x230 fs/open.c:878
do_last fs/namei.c:3455 [inline]
path_openat+0xb6b/0x2b70 fs/namei.c:3597
do_filp_open+0x1a1/0x280 fs/namei.c:3631
do_sys_open+0x2ca/0x590 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289

Showing all locks held in the system:
1 lock held by khungtaskd/23:
#0: (tasklist_lock){.+.+}, at: [<ffffffffa3a00e0c>]
debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4541
2 locks held by getty/1757:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffffa4538782>]
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:275
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffffa4533ba7>]
n_tty_read+0x1f7/0x1700 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.2/1962:
#0: (loop_ctl_mutex/1){+.+.}, at: [<ffffffffa45e87a3>]
lo_ioctl+0x83/0x1970 drivers/block/loop.c:1405
2 locks held by syz-executor.4/1970:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e16ee3>]
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
#1: (loop_index_mutex){+.+.}, at: [<ffffffffa45e3b99>] lo_open+0x19/0xb0
drivers/block/loop.c:1624
2 locks held by syz-executor.5/1972:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e16ee3>]
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
#1: (loop_index_mutex){+.+.}, at: [<ffffffffa45e3b99>] lo_open+0x19/0xb0
drivers/block/loop.c:1624
2 locks held by syz-executor.0/1975:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e16ee3>]
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
#1: (loop_index_mutex){+.+.}, at: [<ffffffffa45e3b99>] lo_open+0x19/0xb0
drivers/block/loop.c:1624
2 locks held by syz-executor.1/1978:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e16ee3>]
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
#1: (loop_index_mutex){+.+.}, at: [<ffffffffa45e3b99>] lo_open+0x19/0xb0
drivers/block/loop.c:1624
2 locks held by syz-executor.3/3042:
#0: (loop_ctl_mutex/1){+.+.}, at: [<ffffffffa45e87a3>]
lo_ioctl+0x83/0x1970 drivers/block/loop.c:1405
#1: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa431b5ab>]
blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
3 locks held by blkid/3043:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e167d1>]
__blkdev_put+0xb1/0x6d0 fs/block_dev.c:1778
#1: (loop_index_mutex){+.+.}, at: [<ffffffffa45ea1d9>]
lo_release+0x19/0x190 drivers/block/loop.c:1667
#2: (loop_ctl_mutex#2){+.+.}, at: [<ffffffffa45ea238>] __lo_release
drivers/block/loop.c:1644 [inline]
#2: (loop_ctl_mutex#2){+.+.}, at: [<ffffffffa45ea238>]
lo_release+0x78/0x190 drivers/block/loop.c:1668
1 lock held by blkid/3045:
#0: (loop_ctl_mutex/1){+.+.}, at: [<ffffffffa45e87a3>]
lo_ioctl+0x83/0x1970 drivers/block/loop.c:1405
1 lock held by blkid/3048:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e16ee3>]
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
1 lock held by blkid/3052:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e16ee3>]
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457
1 lock held by blkid/3054:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffffa3e16ee3>]
__blkdev_get+0xf3/0xf90 fs/block_dev.c:1457

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

NMI backtrace for cpu 1
CPU: 1 PID: 23 Comm: khungtaskd Not tainted 4.14.105+ #29
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0xb9/0x10e lib/dump_stack.c:53
nmi_cpu_backtrace.cold+0x47/0x86 lib/nmi_backtrace.c:101
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.105+ #29
task: ffffffffa5c31200 task.stack: ffffffffa5c00000
RIP: 0010:cpumask_next_and+0x12/0xa0 lib/cpumask.c:35
RSP: 0018:ffff8881dba078d0 EFLAGS: 00000246
RAX: ffffed103b740fa2 RBX: ffff8881dba07ad8 RCX: 1ffffffff4c06939
RDX: ffff8881dba1e4b8 RSI: ffff8881da96af28 RDI: 0000000000000000
RBP: 000000000002a200 R08: 0000000000000001 R09: ffff8881dba2a200
R10: ffffed103b740f64 R11: ffff8881dba07b27 R12: ffff8881dba2a200
R13: ffff8881da96af28 R14: ffff8881dba1e4b8 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8881dba00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000781f04 CR3: 00000001bc626005 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
update_sg_lb_stats kernel/sched/fair.c:9497 [inline]
update_sd_lb_stats kernel/sched/fair.c:9746 [inline]
find_busiest_group+0x3b8/0x3950 kernel/sched/fair.c:10083
load_balance+0x3f9/0x2a00 kernel/sched/fair.c:10395
rebalance_domains+0x785/0xd50 kernel/sched/fair.c:11091
run_rebalance_domains+0x60f/0x8e0 kernel/sched/fair.c:11355
__do_softirq+0x234/0x9ca kernel/softirq.c:288
invoke_softirq kernel/softirq.c:368 [inline]
irq_exit+0x114/0x150 kernel/softirq.c:409
reschedule_interrupt+0x84/0x90 arch/x86/entry/entry_64.S:811
</IRQ>
RIP: 0010:native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:58
RSP: 0018:ffffffffa5c07d48 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff02
RAX: 0000000000000007 RBX: ffffffffa602a508 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffffa5c31a2c
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffffa5c31200 R15: dffffc0000000000
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
default_idle+0x50/0x390 arch/x86/kernel/process.c:564
cpuidle_idle_call kernel/sched/idle.c:159 [inline]
do_idle+0x2e6/0x390 kernel/sched/idle.c:268
cpu_startup_entry+0xc6/0xd0 kernel/sched/idle.c:374
start_kernel+0x712/0x74a init/main.c:710
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240
Code: 48 63 d2 e8 81 75 37 ff 5b 5d c3 0f 1f 40 00 66 2e 0f 1f 84 00 00 00
00 00 41 57 41 89 ff 41 56 49 89 d6 41 55 49 89 f5 41 54 55 <48> c7 c5 c4
4a 03 a6 49 89 ec 53 83 e5 07 e8 eb 15 b1 fe 49 c1


---
This bug 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 syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
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syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 13cc5401 ANDROID: arm-smccc: fix clang build
git tree: android-4.9
console output: https://syzkaller.appspot.com/x/log.txt?x=15cbddbb800000
kernel config: https://syzkaller.appspot.com/x/.config?x=fab87dc152343eaa
dashboard link: https://syzkaller.appspot.com/bug?extid=802dc7e8b66aa63717bd
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16f53f87800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=112066c7800000

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

Reported-by: syzbot+802dc7...@syzkaller.appspotmail.com

INFO: task syzkaller641933:3915 blocked for more than 120 seconds.
Not tainted 4.9.95-g13cc540 #2

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

syzkaller641933 D28104 3915 3914 0x00000000
ffff8801b61cb000 ffff8801d98a9f80 ffff8801b631af40 ffff8801b61ce000
ffff8801db321b98 ffff8801d71cf9c8 ffffffff839e140d ffff8801b61cb8c8
ffffed0036c39718 ffff8801b61cb000 00fffc0000000000 ffff8801db322468
Call Trace:
[<ffffffff839e2a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
[<ffffffff839e3393>] schedule_preempt_disabled+0x13/0x20
kernel/sched/core.c:3590
[<ffffffff839e7816>] __mutex_lock_common kernel/locking/mutex.c:582
[inline]
[<ffffffff839e7816>] mutex_lock_nested+0x326/0x870
kernel/locking/mutex.c:621
[<ffffffff825c6dbb>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
[<ffffffff81e547a6>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
[<ffffffff81e547a6>] blkdev_ioctl+0x7b6/0x1a70 block/ioctl.c:590
[<ffffffff816302ee>] block_ioctl+0xde/0x120 fs/block_dev.c:1688
[<ffffffff815b04dc>] vfs_ioctl fs/ioctl.c:43 [inline]
[<ffffffff815b04dc>] file_ioctl fs/ioctl.c:493 [inline]
[<ffffffff815b04dc>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
[<ffffffff815b155f>] SYSC_ioctl fs/ioctl.c:694 [inline]
[<ffffffff815b155f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839f2313>] 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: [<ffffffff813646bc>]
check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
#0: (rcu_read_lock){......}, at: [<ffffffff813646bc>]
watchdog+0x11c/0xa20 kernel/hung_task.c:239
#1: (tasklist_lock){.+.+..}, at: [<ffffffff81423cb0>]
debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3680:
#0: (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d575c>]
__fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3775:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f04b2>]
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211c722>]
n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
1 lock held by syzkaller641933/3915:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syzkaller641933/4048:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syzkaller641933/4068:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syzkaller641933/4074:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syzkaller641933/4082:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syzkaller641933/4083:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syzkaller641933/4091:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syzkaller641933/4097:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

1 lock held by blkid/4105:

#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c6dbb>]
lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

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

NMI backtrace for cpu 0
CPU: 0 PID: 518 Comm: khungtaskd Not tainted 4.9.95-g13cc540 #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
ffff8801d87bfd08 ffffffff81eb0ba9 0000000000000000 0000000000000000
0000000000000000 0000000000000001 ffffffff810b7d60 ffff8801d87bfd40
ffffffff81ebbed7 0000000000000000 0000000000000000 0000000000000002
Call Trace:
[<ffffffff81eb0ba9>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81eb0ba9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff81ebbed7>] nmi_cpu_backtrace.cold.2+0x48/0x87
lib/nmi_backtrace.c:99
[<ffffffff81ebbe6a>] 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
[<ffffffff81364c54>] trigger_all_cpu_backtrace include/linux/nmi.h:58
[inline]
[<ffffffff81364c54>] check_hung_task kernel/hung_task.c:125 [inline]
[<ffffffff81364c54>] check_hung_uninterruptible_tasks
kernel/hung_task.c:182 [inline]
[<ffffffff81364c54>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
[<ffffffff8119ad2d>] kthread+0x26d/0x300 kernel/kthread.c:211
[<ffffffff839f24dc>] 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 0xffffffff839f0f16

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: bd23e3af UPSTREAM: timer: Export destroy_hrtimer_on_stack()
git tree: android-4.4
console output: https://syzkaller.appspot.com/x/log.txt?x=12830b17800000
kernel config: https://syzkaller.appspot.com/x/.config?x=52b70c75fab5af5
dashboard link: https://syzkaller.appspot.com/bug?extid=52df01cbf8d17b8aecf7

compiler: gcc (GCC) 8.0.1 20180413 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15215b17800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1651f007800000

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

Reported-by: syzbot+52df01...@syzkaller.appspotmail.com

INFO: task syz-executor950:3844 blocked for more than 120 seconds.
Not tainted 4.4.128-gbd23e3a #20

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

syz-executor950 D ffff8800ba8dfa68 27856 3844 3843 0x00000000
ffff8800ba8dfa68 0000000000000000 ffff8801d8eb38e0 ffffed003b1d671b
ffff8801d8eb3000 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
ffff8801db21f4c0 ffff8800b2396000 ffff8801d8eb3000 0000000000000000
Call Trace:
[<ffffffff838b074a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
[<ffffffff838b0ee3>] schedule_preempt_disabled+0x13/0x20
kernel/sched/core.c:3392
[<ffffffff838b7027>] __mutex_lock_common kernel/locking/mutex.c:582
[inline]
[<ffffffff838b7027>] mutex_lock_nested+0x307/0x850
kernel/locking/mutex.c:621
[<ffffffff8251a4fb>] lo_ioctl+0x8b/0x1ad0 drivers/block/loop.c:1351
[<ffffffff81db6d08>] __blkdev_driver_ioctl block/ioctl.c:288 [inline]
[<ffffffff81db6d08>] blkdev_ioctl+0x7b8/0x19c0 block/ioctl.c:584
[<ffffffff815d34ae>] block_ioctl+0xde/0x120 fs/block_dev.c:1625
[<ffffffff8155929f>] vfs_ioctl fs/ioctl.c:43 [inline]
[<ffffffff8155929f>] file_ioctl fs/ioctl.c:470 [inline]
[<ffffffff8155929f>] do_vfs_ioctl+0x63f/0xf40 fs/ioctl.c:605
[<ffffffff81559c2f>] SYSC_ioctl fs/ioctl.c:622 [inline]
[<ffffffff81559c2f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
[<ffffffff838be765>] entry_SYSCALL_64_fastpath+0x22/0x9e
1 lock held by syz-executor950/3844:
#0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff8251a4fb>]
lo_ioctl+0x8b/0x1ad0 drivers/block/loop.c:1351
Sending NMI to all CPUs:

NMI backtrace for cpu 0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.128-gbd23e3a #20

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

task: ffffffff84417840 task.stack: ffffffff84400000
RIP: 0010:[<ffffffff810cc306>] [<ffffffff810cc306>]
native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffffffff84407dc8 EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffffff84a05868 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff8441811c
RBP: ffffffff84407dc8 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000

R13: 0000000000000000 R14: fffffbfff074890c R15: ffffffff84a05868
FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00000000019a9f10 CR3: 00000000b656e000 CR4: 0000000000160670

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Stack:
ffffffff84407e00 ffffffff81025da5 ffffffff84408000 0000000000000000
0000000000000000 fffffbfff074890c ffffffff84a05868 ffffffff84407e10
ffffffff810272f0 ffffffff84407e28 ffffffff8121b9c7 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
[<ffffffff8121b9c7>] default_idle_call+0x57/0x70 kernel/sched/idle.c:93
[<ffffffff8121c16f>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
[<ffffffff8121c16f>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
[<ffffffff8121c16f>] cpu_startup_entry+0x6af/0x780 kernel/sched/idle.c:301
[<ffffffff838ab8b1>] rest_init+0x188/0x18e init/main.c:410
[<ffffffff84a4b8a1>] start_kernel+0x6b3/0x6e7 init/main.c:682
[<ffffffff84a4a30f>] x86_64_start_reservations+0x29/0x2b
arch/x86/kernel/head64.c:196
[<ffffffff84a4a450>] x86_64_start_kernel+0x13f/0x162
arch/x86/kernel/head64.c:185
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

NMI backtrace for cpu 1

CPU: 1 PID: 492 Comm: khungtaskd Not tainted 4.4.128-gbd23e3a #20

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

task: ffff8800bb956000 task.stack: ffff8801d8f08000
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:ffff8801d8f0fcc8 EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8801d8f0fcf0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f7a0
FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f820ea05000 CR3: 00000000b656e000 CR4: 0000000000160670

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Stack:
ffffffff8446f7a0 ffffffff84a187a0 0000000000000007 fffffbfff0942ba4
0000000000000040 ffff8801d8f0fd10 ffffffff810b5d21 ffffffff83c0b0e0
0000000000000003 ffff8801d8f0fd68 ffffffff81e18b43 ffffffff8140da9f
Call Trace:
[<ffffffff810b5d21>] nmi_raise_cpu_backtrace+0x61/0x80
arch/x86/kernel/apic/hw_nmi.c:33
[<ffffffff81e18b43>] 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
[<ffffffff8141a189>] trigger_all_cpu_backtrace include/linux/nmi.h:44
[inline]
[<ffffffff8141a189>] check_hung_task kernel/hung_task.c:125 [inline]
[<ffffffff8141a189>] check_hung_uninterruptible_tasks
kernel/hung_task.c:182 [inline]
[<ffffffff8141a189>] watchdog.cold.1+0xd3/0xee kernel/hung_task.c:238
[<ffffffff81190748>] kthread+0x268/0x300 kernel/kthread.c:211
[<ffffffff838beb95>] 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 82