Hello,
syzkaller hit the following crash on
2391f0b4808e3d5af348324d69f5f45c56a26836
git://
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
Unfortunately, I don't have any reproducer for this bug yet.
unregister_netdevice: waiting for to become free. Usage count = 2
INFO: task syz-executor0:23858 blocked for more than 120 seconds.
Not tainted 4.15.0-rc2+ #207
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0 D24384 23858 3346 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2799 [inline]
__schedule+0x8eb/0x2060 kernel/sched/core.c:3375
schedule+0xf5/0x430 kernel/sched/core.c:3434
io_schedule+0x1c/0x70 kernel/sched/core.c:5042
wait_on_page_bit_common mm/filemap.c:1100 [inline]
__lock_page+0x585/0x740 mm/filemap.c:1273
lock_page include/linux/pagemap.h:483 [inline]
pagecache_get_page+0x672/0xba0 mm/filemap.c:1554
find_lock_page include/linux/pagemap.h:297 [inline]
truncate_inode_pages_range+0xc05/0x1f90 mm/truncate.c:400
blkdev_fallocate+0x1ff/0x3b0 fs/block_dev.c:1991
vfs_fallocate+0x342/0x700 fs/open.c:319
SYSC_fallocate fs/open.c:342 [inline]
SyS_fallocate+0x53/0x90 fs/open.c:336
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x4529d9
RSP: 002b:00007f2587578c58 EFLAGS: 00000212 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 00000000004529d9
RDX: 0000000000000000 RSI: 0000000000000011 RDI: 0000000000000019
RBP: 0000000000000408 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000044400004 R11: 0000000000000212 R12: 00000000006f3160
R13: 00000000ffffffff R14: 00007f25875796d4 R15: 0000000000000000
Showing all locks held in the system:
2 locks held by khungtaskd/674:
#0: (rcu_read_lock){....}, at: [<00000000e30adf30>]
check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
#0: (rcu_read_lock){....}, at: [<00000000e30adf30>] watchdog+0x1c5/0xd60
kernel/hung_task.c:249
#1: (tasklist_lock){.?.?}, at: [<000000009ab1356f>]
debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554
2 locks held by getty/3053:
#0: (&tty->ldisc_sem){++++}, at: [<000000002fbbac43>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a3f10257>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3054:
#0: (&tty->ldisc_sem){++++}, at: [<000000002fbbac43>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a3f10257>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
unregister_netdevice: waiting for to become free. Usage count = 2
2 locks held by getty/3055:
#0: (&tty->ldisc_sem){++++}, at: [<000000002fbbac43>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a3f10257>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3056:
#0: (&tty->ldisc_sem){++++}, at: [<000000002fbbac43>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a3f10257>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3057:
#0: (&tty->ldisc_sem){++++}, at: [<000000002fbbac43>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a3f10257>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3058:
#0: (&tty->ldisc_sem){++++}, at: [<000000002fbbac43>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a3f10257>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
3 locks held by kworker/u4:6/3916:
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000008938d852>]
__write_once_size include/linux/compiler.h:212 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000008938d852>]
atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000008938d852>]
atomic_long_set include/asm-generic/atomic-long.h:57 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000008938d852>]
set_work_data kernel/workqueue.c:618 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000008938d852>]
set_work_pool_and_clear_pending kernel/workqueue.c:645 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000008938d852>]
process_one_work+0xad4/0x1be0 kernel/workqueue.c:2083
#1: (net_cleanup_work){+.+.}, at: [<00000000f13a63c1>]
process_one_work+0xb2f/0x1be0 kernel/workqueue.c:2087
#2: (net_mutex){+.+.}, at: [<00000000a76af5a4>] cleanup_net+0x247/0xb60
net/core/net_namespace.c:450
2 locks held by getty/23956:
#0: (&tty->ldisc_sem){++++}, at: [<000000002fbbac43>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000a3f10257>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 674 Comm: khungtaskd Not tainted 4.15.0-rc2+ #207
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
check_hung_task kernel/hung_task.c:132 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
watchdog+0x90c/0xd60 kernel/hung_task.c:249
kthread+0x37a/0x440 kernel/kthread.c:238
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10
arch/x86/include/asm/irqflags.h:54
---
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