INFO: task hung in do_rmdir (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 050cdc6c9501 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=106e412e400000
kernel config: https://syzkaller.appspot.com/x/.config?x=49927b422dcf0b29
dashboard link: https://syzkaller.appspot.com/bug?extid=4d57431c6c3bc76f28b4
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4d5743...@syzkaller.appspotmail.com

FAT-fs (loop0): error, invalid access to FAT (entry 0x000002a1)
FAT-fs (loop0): Filesystem has been set read-only
FAT-fs (loop0): error, invalid access to FAT (entry 0x000002a1)
INFO: task syz-executor0:21669 blocked for more than 140 seconds.
Not tainted 4.19.0-rc1+ #212
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0 D21768 21669 4493 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2825 [inline]
__schedule+0x87c/0x1df0 kernel/sched/core.c:3473
schedule+0xfb/0x450 kernel/sched/core.c:3517
__rwsem_down_write_failed_common+0x98b/0x1650
kernel/locking/rwsem-xadd.c:566
rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:595
call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117
__down_write arch/x86/include/asm/rwsem.h:142 [inline]
down_write_nested+0xae/0x130 kernel/locking/rwsem.c:194
inode_lock_nested include/linux/fs.h:773 [inline]
do_rmdir+0x38f/0x630 fs/namei.c:3929
__do_sys_unlinkat fs/namei.c:4103 [inline]
__se_sys_unlinkat fs/namei.c:4097 [inline]
__x64_sys_unlinkat+0xea/0x120 fs/namei.c:4097
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457089
Code: 08 e8 3b a9 fb ff 48 8b 44 24 20 48 8b 4c 24 18 48 8b 54 24 38 48 8b
7c 24 48 eb 8d 48 8b 6c 24 50 48 83 c4 58 c3 48 89 04 24 <48> 89 5c 24 08
e8 0d a9 fb ff 48 8b 44 24 40 48 8b 4c 24 48 48 8b
RSP: 002b:00007f15c6199c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f15c619a6d4 RCX: 0000000000457089
RDX: 0000000000000200 RSI: 0000000020000080 RDI: 000000000000000f
RBP: 00000000009301e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d6d68 R14: 00000000004ca166 R15: 0000000000000002
INFO: task syz-executor0:21670 blocked for more than 140 seconds.
Not tainted 4.19.0-rc1+ #212
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0 D25408 21670 4493 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2825 [inline]
__schedule+0x87c/0x1df0 kernel/sched/core.c:3473
schedule+0xfb/0x450 kernel/sched/core.c:3517
__rwsem_down_write_failed_common+0x98b/0x1650
kernel/locking/rwsem-xadd.c:566
rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:595
call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117
__down_write arch/x86/include/asm/rwsem.h:142 [inline]
down_write_nested+0xae/0x130 kernel/locking/rwsem.c:194
inode_lock_nested include/linux/fs.h:773 [inline]
filename_create+0x1b2/0x5b0 fs/namei.c:3635
user_path_create fs/namei.c:3693 [inline]
do_mkdirat+0xda/0x310 fs/namei.c:3832
__do_sys_mkdir fs/namei.c:3856 [inline]
__se_sys_mkdir fs/namei.c:3854 [inline]
__x64_sys_mkdir+0x5c/0x80 fs/namei.c:3854
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457089
Code: 08 e8 3b a9 fb ff 48 8b 44 24 20 48 8b 4c 24 18 48 8b 54 24 38 48 8b
7c 24 48 eb 8d 48 8b 6c 24 50 48 83 c4 58 c3 48 89 04 24 <48> 89 5c 24 08
e8 0d a9 fb ff 48 8b 44 24 40 48 8b 4c 24 48 48 8b
RSP: 002b:00007f15c6178c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007f15c61796d4 RCX: 0000000000457089
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240
RBP: 0000000000930280 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d2688 R14: 00000000004c26c5 R15: 0000000000000003

Showing all locks held in the system:
1 lock held by khungtaskd/774:
#0: 00000000793076b2 (rcu_read_lock){....}, at:
debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4436
1 lock held by rsyslogd/4357:
#0: 00000000caa44345 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200
fs/file.c:766
2 locks held by getty/4447:
#0: 00000000b854c9b7 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353
#1: 0000000059097c12 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4448:
#0: 00000000d89bbde9 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353
#1: 00000000483fc588 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4449:
#0: 000000001c0293d9 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353
#1: 00000000f21e9004 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4450:
#0: 00000000118ffb8e (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353
#1: 00000000ad419ff0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4451:
#0: 00000000cf0da65c (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353
#1: 000000004ba5c890 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4452:
#0: 000000006859f446 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353
#1: 000000009885fa5f (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by getty/4453:
#0: 000000005866504e (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353
#1: 000000005b5b4418 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140
2 locks held by syz-executor0/21669:
#0: 00000000cf2ca39a (sb_writers#21){.+.+}, at: sb_start_write
include/linux/fs.h:1566 [inline]
#0: 00000000cf2ca39a (sb_writers#21){.+.+}, at: mnt_want_write+0x3f/0xc0
fs/namespace.c:360
#1: 00000000e9a5802b (&sb->s_type->i_mutex_key#23/1){+.+.}, at:
inode_lock_nested include/linux/fs.h:773 [inline]
#1: 00000000e9a5802b (&sb->s_type->i_mutex_key#23/1){+.+.}, at:
do_rmdir+0x38f/0x630 fs/namei.c:3929
2 locks held by syz-executor0/21670:
#0: 00000000cf2ca39a (sb_writers#21){.+.+}, at: sb_start_write
include/linux/fs.h:1566 [inline]
#0: 00000000cf2ca39a (sb_writers#21){.+.+}, at: mnt_want_write+0x3f/0xc0
fs/namespace.c:360
#1: 00000000e9a5802b (&sb->s_type->i_mutex_key#23/1){+.+.}, at:
inode_lock_nested include/linux/fs.h:773 [inline]
#1: 00000000e9a5802b (&sb->s_type->i_mutex_key#23/1){+.+.}, at:
filename_create+0x1b2/0x5b0 fs/namei.c:3635
3 locks held by syz-executor0/21671:

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

NMI backtrace for cpu 0
CPU: 0 PID: 774 Comm: khungtaskd Not tainted 4.19.0-rc1+ #212
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
nmi_cpu_backtrace.cold.3+0x48/0x88 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x151/0x192 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:144 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline]
watchdog+0xb39/0x1040 kernel/hung_task.c:265
kthread+0x35a/0x420 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
Sending NMI from CPU 0 to CPUs 1:
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.059
msecs
NMI backtrace for cpu 1
CPU: 1 PID: 21671 Comm: syz-executor0 Not tainted 4.19.0-rc1+ #212
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:lockdep_hardirqs_on+0x366/0x5c0 kernel/locking/lockdep.c:2869
Code: 48 89 fa 48 c1 ea 03 0f b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0
0f 85 86 01 00 00 80 3d d8 c8 2b 07 00 0f 85 b2 01 00 00 <65> 48 8b 1c 25
40 ee 01 00 48 8d bb 0c 08 00 00 48 b8 00 00 00 00
RSP: 0018:ffff880189246dc8 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000003 RCX: ffffc90003a1a000
RDX: 0000000000000000 RSI: ffffffff8182ccf4 RDI: ffffffff888b78c8
RBP: ffff880189246dd8 R08: ffff880191a3c180 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff81d6a560
R13: dffffc0000000000 R14: ffffffff81d6a560 R15: 0000000000000000
FS: 00007f15c6158700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000001abef0000 CR4: 00000000001406e0
DR0: 000000000000b8c4 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
trace_hardirqs_on+0xbd/0x2c0 kernel/trace/trace_preemptirq.c:30
lookup_bh_lru fs/buffer.c:1279 [inline]
__find_get_block+0x2c0/0xdf0 fs/buffer.c:1291
__getblk_slow fs/buffer.c:1040 [inline]
__getblk_gfp+0x2be/0xb10 fs/buffer.c:1321
__getblk include/linux/buffer_head.h:380 [inline]
__breadahead+0x8c/0x160 fs/buffer.c:1331
sb_breadahead include/linux/buffer_head.h:319 [inline]
fat_dir_readahead fs/fat/dir.c:66 [inline]
fat__get_entry+0x4ce/0xa30 fs/fat/dir.c:99
fat_get_entry fs/fat/dir.c:129 [inline]
fat_get_short_entry+0x13c/0x2c0 fs/fat/dir.c:876
fat_scan+0x111/0x340 fs/fat/dir.c:961
msdos_find+0x10e/0x320 fs/fat/namei_msdos.c:129
msdos_lookup+0x13c/0x320 fs/fat/namei_msdos.c:209
lookup_open+0x72e/0x1b90 fs/namei.c:3213
do_last fs/namei.c:3324 [inline]
path_openat+0x15d4/0x5300 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x584/0x720 fs/open.c:1063
__do_sys_open fs/open.c:1081 [inline]
__se_sys_open fs/open.c:1076 [inline]
__x64_sys_open+0x7e/0xc0 fs/open.c:1076
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457089
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f15c6157c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f15c61586d4 RCX: 0000000000457089
RDX: 0000000000000020 RSI: 0000000000141046 RDI: 00000000200001c0
RBP: 0000000000930320 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d2b68 R14: 00000000004ee1df R15: 0000000000000004


---
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:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
syzbot.