INFO: task hung in d_alloc_parallel

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
f2d285669aae656dfeafa0bf25e86bbbc5d22329 (Tue Apr 3 17:45:39 2018 +0000)
Merge tag 'pm-4.17-rc1' of
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=360d1f214fc995563def

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=5163147883184128
Kernel config: https://syzkaller.appspot.com/x/.config?id=686016073509112605
compiler: gcc (GCC) 7.1.1 20170620
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk]

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+360d1f...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
INFO: task syz-executor0:10410 blocked for more than 120 seconds.
device loop0 blocksize: 4096
Not tainted 4.16.0+ #13
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0 D23232 10410 4513 0x00000004
__find_get_block_slow() failed. block=3, b_blocknr=24
Call Trace:
context_switch kernel/sched/core.c:2848 [inline]
__schedule+0x8fb/0x1ef0 kernel/sched/core.c:3490
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
schedule+0xf5/0x430 kernel/sched/core.c:3549
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
d_wait_lookup fs/dcache.c:2460 [inline]
d_alloc_parallel+0x134a/0x1b40 fs/dcache.c:2542
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
lookup_slow+0x1e5/0x4d0 fs/namei.c:1617
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
walk_component+0x89f/0x13d0 fs/namei.c:1763
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
link_path_walk+0xd4e/0x1470 fs/namei.c:2092
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
path_lookupat+0xf3/0xba0 fs/namei.c:2280
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
do_o_path fs/namei.c:3479 [inline]
path_openat+0x1d85/0x3590 fs/namei.c:3508
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
do_filp_open+0x25b/0x3b0 fs/namei.c:3554
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
do_sys_open+0x502/0x6d0 fs/open.c:1101
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
SYSC_openat fs/open.c:1128 [inline]
SyS_openat+0x30/0x40 fs/open.c:1122
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
entry_SYSCALL_64_after_hwframe+0x42/0xb7
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
RIP: 0033:0x4552d9
RSP: 002b:00007fda7842ec68 EFLAGS: 00000246
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fda7842f6d4 RCX: 00000000004552d9
RDX: 0000000000200002 RSI: 0000000020000040 RDI: ffffffffffffff9c
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
RBP: 000000000072bf58 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000420 R14: 00000000006f93a0 R15: 0000000000000001

Showing all locks held in the system:
2 locks held by khungtaskd/878:
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
#0: 00000000a6ef2886
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
(rcu_read_lock){....}, at: check_hung_uninterruptible_tasks
kernel/hung_task.c:175 [inline]
(rcu_read_lock){....}, at: watchdog+0x1d6/0xd70 kernel/hung_task.c:249
__find_get_block_slow() failed. block=3, b_blocknr=24
#1: 00000000d99ef5a7 (
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
tasklist_lock){.+.+}, at: debug_show_all_locks+0xd3/0x3d0
kernel/locking/lockdep.c:4470
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
1 lock held by rsyslogd/4350:
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
#0: 000000004817821b (
__find_get_block_slow() failed. block=3, b_blocknr=24
&f->f_pos_lock){+.+.}, at: __fdget_pos+0x165/0x1a0 fs/file.c:766
b_state=0x00000029, b_size=512
2 locks held by getty/4441:
#0: 000000003d843baf (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
device loop0 blocksize: 4096
#1: 00000000b9e53f1a (&ldata->atomic_read_lock
__find_get_block_slow() failed. block=3, b_blocknr=24
){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131
2 locks held by getty/4442:
b_state=0x00000029, b_size=512
#0: 000000005a86d579 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1:
device loop0 blocksize: 4096
00000000dd5161e4 (&ldata->atomic_read_lock){+.+.}
__find_get_block_slow() failed. block=3, b_blocknr=24
, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131
2 locks held by getty/4443:
b_state=0x00000029, b_size=512
#0: 000000005b952116 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1:
device loop0 blocksize: 4096
00000000fb054a50 (&ldata->atomic_read_lock){+.+.}
__find_get_block_slow() failed. block=3, b_blocknr=24
, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131
2 locks held by getty/4444:
#0: 0000000088e6511e (&tty->ldisc_sem
b_state=0x00000029, b_size=512
){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 00000000d38ad8bb (&ldata->atomic_read_lock){+.+.}
device loop0 blocksize: 4096
, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131
2 locks held by getty/4445:
__find_get_block_slow() failed. block=3, b_blocknr=24
#0: 00000000bbd28c78 (
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40
drivers/tty/tty_ldsem.c:365
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
#1: 00000000e5a0afe4 (
b_state=0x00000029, b_size=512
&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40
drivers/tty/n_tty.c:2131
device loop0 blocksize: 4096
2 locks held by getty/4446:
#0: 0000000015fd8bad
__find_get_block_slow() failed. block=3, b_blocknr=24
(&tty->ldisc_sem){++++}
b_state=0x00000029, b_size=512
, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: 000000007b82da19 (&ldata->atomic_read_lock){+.+.}
device loop0 blocksize: 4096
, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131
2 locks held by getty/4447:
__find_get_block_slow() failed. block=3, b_blocknr=24
#0: 00000000b39c0f81 (
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40
drivers/tty/tty_ldsem.c:365
b_state=0x00000029, b_size=512
#1: 0000000013881aec (&ldata->atomic_read_lock
device loop0 blocksize: 4096
){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131
1 lock held by syz-executor0/10410:
__find_get_block_slow() failed. block=3, b_blocknr=24
#0: 00000000a18e656c (&sb->s_type->i_mutex_key#16){++++}, at:
inode_lock_shared include/linux/fs.h:723 [inline]
#0: 00000000a18e656c (&sb->s_type->i_mutex_key#16){++++}, at:
lookup_slow+0x18e/0x4d0 fs/namei.c:1612

b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 878 Comm: khungtaskd Not tainted 4.16.0+ #13
__find_get_block_slow() failed. block=3, b_blocknr=24
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+0x1a7/0x27d lib/dump_stack.c:53
b_state=0x00000029, b_size=512
nmi_cpu_backtrace+0x1e0/0x220 lib/nmi_backtrace.c:103
nmi_trigger_cpumask_backtrace+0x123/0x180 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+0x969/0xd70 kernel/hung_task.c:249
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=3, b_blocknr=24
b_state=0x00000029, b_size=512
kthread+0x33c/0x400 kernel/kthread.c:238
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411
Sending NMI from CPU 1 to CPUs 0:
device loop0 blocksize: 4096
NMI backtrace for cpu 0
CPU: 0 PID: 10368 Comm: syz-executor0 Not tainted 4.16.0+ #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__wrmsr arch/x86/include/asm/msr.h:105 [inline]
RIP: 0010:native_write_msr+0xa/0x30 arch/x86/include/asm/msr.h:162
RSP: 0018:ffff8801db007d40 EFLAGS: 00000046
RAX: 0000000000000b2d RBX: 0000000000000838 RCX: 0000000000000838
RDX: 0000000000000000 RSI: 0000000000000b2d RDI: 0000000000000838
RBP: ffff8801db007d40 R08: ffff88021fff801c R09: ffff88021fff8008
R10: ffff88021fff801d R11: ffff88021fff8010 R12: 0000000000000b2d
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000003
FS: 00007fda78450700(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000001c702f000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
paravirt_write_msr arch/x86/include/asm/paravirt.h:117 [inline]
native_apic_msr_write+0x5c/0x80 arch/x86/include/asm/apic.h:208
apic_write arch/x86/include/asm/apic.h:396 [inline]
lapic_next_event+0x54/0x80 arch/x86/kernel/apic/apic.c:460
clockevents_program_event+0x248/0x2e0 kernel/time/clockevents.c:344
tick_program_event+0x7c/0x100 kernel/time/tick-oneshot.c:48
hrtimer_interrupt+0x2f9/0x6f0 kernel/time/hrtimer.c:1482
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:862
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783
[inline]
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:1678 [inline]
RIP: 0010:vprintk_emit+0xa68/0xb90 kernel/printk/printk.c:1906
RSP: 0018:ffff88018b62e728 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff12
RAX: 0000000000040000 RBX: 1ffffffff10a2555 RCX: ffffffff815afd3f
RDX: 0000000000040000 RSI: ffffc90001ea9000 RDI: 0000000000000246
RBP: ffff88018b62e8b0 R08: 1ffff100316c5cb3 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000001c
R13: ffff88018b62e808 R14: ffffed00316c5d01 R15: ffffffff89daff80
vprintk_default+0x28/0x30 kernel/printk/printk.c:1947
vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
printk+0xaa/0xca kernel/printk/printk.c:1980
__find_get_block_slow fs/buffer.c:238 [inline]
__find_get_block+0xdad/0xdf0 fs/buffer.c:1310
__getblk_slow fs/buffer.c:1055 [inline]
__getblk_gfp+0x26c/0xb40 fs/buffer.c:1336
__bread_gfp+0x2d/0x2a0 fs/buffer.c:1370
sb_bread include/linux/buffer_head.h:309 [inline]
fat__get_entry+0x195/0x910 fs/fat/dir.c:101
fat_get_entry fs/fat/dir.c:129 [inline]
fat_search_long+0x32f/0x14b0 fs/fat/dir.c:477
vfat_find+0x134/0x180 fs/fat/namei_vfat.c:697
vfat_lookup+0xf3/0x770 fs/fat/namei_vfat.c:720
lookup_slow+0x282/0x4d0 fs/namei.c:1634
walk_component+0x89f/0x13d0 fs/namei.c:1763
link_path_walk+0xd4e/0x1470 fs/namei.c:2092
path_lookupat+0xf3/0xba0 fs/namei.c:2280
do_o_path fs/namei.c:3479 [inline]
path_openat+0x1d85/0x3590 fs/namei.c:3508
do_filp_open+0x25b/0x3b0 fs/namei.c:3554
do_sys_open+0x502/0x6d0 fs/open.c:1101
SYSC_openat fs/open.c:1128 [inline]
SyS_openat+0x30/0x40 fs/open.c:1122
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4552d9
RSP: 002b:00007fda7844fc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fda784506d4 RCX: 00000000004552d9
RDX: 0000000000200002 RSI: 0000000020000040 RDI: ffffffffffffff9c
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000420 R14: 00000000006f93a0 R15: 0000000000000000
Code: 5d c3 0f 21 d0 5d c3 0f 21 d8 5d c3 0f 21 f0 5d c3 0f 0b 0f 1f 40 00
66 2e 0f 1f 84 00 00 00 00 00 55 89 f9 89 f0 48 89 e5 0f 30 <0f> 1f 44 00
00 5d c3 48 89 d6 89 c2 48 c1 e6 20 48 09 d6 31 d2


---
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