INFO: task hung in filename_create

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 47bbcd6b ANDROID: Fix massive cpufreq_times memory leaks
git tree: android-4.9
console output: https://syzkaller.appspot.com/x/log.txt?x=1779bf94400000
kernel config: https://syzkaller.appspot.com/x/.config?x=f2dbd0c9dd968786
dashboard link: https://syzkaller.appspot.com/bug?extid=ff44edecf201011c773a
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=114d8cb4400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12cf14c8400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ff44ed...@syzkaller.appspotmail.com

INFO: task syz-executor235:3915 blocked for more than 140 seconds.
Not tainted 4.9.113-g47bbcd6 #10
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor235 D29088 3915 3911 0x00000004
ffff8801d7c8b000 0000000000000000 ffff8801bc071f80 ffff8801d9a6b000
ffff8801db321c18 ffff8801d6e0fac8 ffffffff839e909d ffffffff81235647
0000000000000000 ffff8801d7c8b8c0 0000000600000007 ffff8801db3224e8
Call Trace:
[<ffffffff839ea69f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
[<ffffffff839f5cd8>] __rwsem_down_write_failed_common
kernel/locking/rwsem-xadd.c:526 [inline]
[<ffffffff839f5cd8>] rwsem_down_write_failed+0x598/0x990
kernel/locking/rwsem-xadd.c:555
[<ffffffff81ee7587>] call_rwsem_down_write_failed+0x17/0x30
arch/x86/lib/rwsem.S:105
[<ffffffff8122c270>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
[<ffffffff8122c270>] down_write_nested+0x60/0xa0 kernel/locking/rwsem.c:174
[<ffffffff815aa01a>] inode_lock_nested include/linux/fs.h:801 [inline]
[<ffffffff815aa01a>] filename_create+0x17a/0x490 fs/namei.c:3639
[<ffffffff815ac49b>] user_path_create fs/namei.c:3697 [inline]
[<ffffffff815ac49b>] SYSC_mkdirat fs/namei.c:3841 [inline]
[<ffffffff815ac49b>] SyS_mkdirat+0xbb/0x260 fs/namei.c:3833
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/520:
#0: (rcu_read_lock){......}, at: [<ffffffff8136675c>]
check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
#0: (rcu_read_lock){......}, at: [<ffffffff8136675c>]
watchdog+0x11c/0xa20 kernel/hung_task.c:239
#1: (tasklist_lock){.+.+..}, at: [<ffffffff81425de7>]
debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3776:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f8142>]
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211ee22>]
n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor235/3915:
#0: (sb_writers#8){.+.+.+}, at: [<ffffffff815e0a8f>] sb_start_write
include/linux/fs.h:1573 [inline]
#0: (sb_writers#8){.+.+.+}, at: [<ffffffff815e0a8f>]
mnt_want_write+0x3f/0xb0 fs/namespace.c:391
#1: (&type->i_mutex_dir_key#3/1){+.+.+.}, at: [<ffffffff815aa01a>]
inode_lock_nested include/linux/fs.h:801 [inline]
#1: (&type->i_mutex_dir_key#3/1){+.+.+.}, at: [<ffffffff815aa01a>]
filename_create+0x17a/0x490 fs/namei.c:3639

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

NMI backtrace for cpu 0
CPU: 0 PID: 520 Comm: khungtaskd Not tainted 4.9.113-g47bbcd6 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
ffff8801d8437d08 ffffffff81eb32a9 0000000000000000 0000000000000000
0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d8437d40
ffffffff81ebe5a7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
[<ffffffff81eb32a9>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81eb32a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff81ebe5a7>] nmi_cpu_backtrace.cold.2+0x48/0x87
lib/nmi_backtrace.c:99
[<ffffffff81ebe53a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f
lib/nmi_backtrace.c:60
[<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20
arch/x86/kernel/apic/hw_nmi.c:37
[<ffffffff81366cf4>] trigger_all_cpu_backtrace include/linux/nmi.h:58
[inline]
[<ffffffff81366cf4>] check_hung_task kernel/hung_task.c:125 [inline]
[<ffffffff81366cf4>] check_hung_uninterruptible_tasks
kernel/hung_task.c:182 [inline]
[<ffffffff81366cf4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
[<ffffffff8119d0ad>] kthread+0x26d/0x300 kernel/kthread.c:211
[<ffffffff839fa15c>] 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
CPU: 1 PID: 3914 Comm: syz-executor235 Not tainted 4.9.113-g47bbcd6 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8801d8539800 task.stack: ffff8801d7128000
RIP: 0010:[<ffffffff8123562a>] c [<ffffffff8123562a>]
mark_held_locks+0xaa/0x130 kernel/locking/lockdep.c:2652
RSP: 0018:ffff8801d712f7b0 EFLAGS: 00000093
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 1ffff1003b0a741d
RDX: 0000000000000002 RSI: ffff8801d853a0f0 RDI: ffff8801d853a112
RBP: ffff8801d712f7f0 R08: ffff8801d853a0e8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d853a0c8
R13: ffffed003b0a7418 R14: ffff8801d8539800 R15: dffffc0000000000
FS: 00007fe2f5e78700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa2cf355000 CR3: 00000001b94e6000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
0000000000000000 c ffff8801d853a0c0 c 0000000600000007 c ffff8801d8539800 c
ffffffff839f969a c ffff8801d712f948 c ffff8801ba8b6318 c 0000000000000001 c
ffff8801d712f810 c ffffffff81235a3b c 0000000000000296 c ffff8801ba8b6318 c
Call Trace:
[<ffffffff81235a3b>] __trace_hardirqs_on_caller
kernel/locking/lockdep.c:2689 [inline]
[<ffffffff81235a3b>] trace_hardirqs_on_caller+0x38b/0x590
kernel/locking/lockdep.c:2736
[<ffffffff81235c4d>] trace_hardirqs_on+0xd/0x10
kernel/locking/lockdep.c:2743
[<ffffffff839f969a>] __raw_spin_unlock_irqrestore
include/linux/spinlock_api_smp.h:162 [inline]
[<ffffffff839f969a>] _raw_spin_unlock_irqrestore+0x5a/0x70
kernel/locking/spinlock.c:191
[<ffffffff81221729>] spin_unlock_irqrestore include/linux/spinlock.h:362
[inline]
[<ffffffff81221729>] prepare_to_wait_event+0x1d9/0x450
kernel/sched/wait.c:238
[<ffffffff81907bbe>] request_wait_answer+0x22e/0x6e0 fs/fuse/dev.c:459
[<ffffffff819086c9>] __fuse_request_send+0x109/0x1b0 fs/fuse/dev.c:480
[<ffffffff819087cd>] fuse_request_send+0x5d/0x70 fs/fuse/dev.c:493
[<ffffffff81912a24>] fuse_simple_request+0x2f4/0x660 fs/fuse/dev.c:551
[<ffffffff8191adc3>] fuse_lookup_name+0x253/0x5d0 fs/fuse/dir.c:369
[<ffffffff8191b22d>] fuse_lookup+0xed/0x3a0 fs/fuse/dir.c:406
[<ffffffff81593e4c>] lookup_real fs/namei.c:1522 [inline]
[<ffffffff81593e4c>] __lookup_hash+0x11c/0x190 fs/namei.c:1542
[<ffffffff815aa046>] filename_create+0x1a6/0x490 fs/namei.c:3640
[<ffffffff815ac49b>] user_path_create fs/namei.c:3697 [inline]
[<ffffffff815ac49b>] SYSC_mkdirat fs/namei.c:3841 [inline]
[<ffffffff815ac49b>] SyS_mkdirat+0xbb/0x260 fs/namei.c:3833
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: cc1 ced c03 c4d c01 cfd c48 c63 cc3 c48 c8d c04 c80 c49
c8d c34 cc4 c48 c8d c7e c22 c48 c89 cf8 c48 c89 cfa c48 cc1
ce8 c03 c83 ce2 c07 c42 c0f cb6 c04 c38 c38 cd0 c7f c04
c<84> cc0 c75 c5e c0f cb6 c46 c22 c8b c55 cd4 ca8 c03 c0f
c45 c55 cd0 ca8 c04 c74 c0c c


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