INFO: task hung in path_openat

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 0ff0788d Merge 4.14.77 into android-4.14
git tree: android-4.14
console output: https://syzkaller.appspot.com/x/log.txt?x=16e9e785400000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c047c057907482d
dashboard link: https://syzkaller.appspot.com/bug?extid=f2858b859f4df284a7e4
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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+f2858b...@syzkaller.appspotmail.com

ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!
INFO: task syz-executor5:31196 blocked for more than 140 seconds.
Not tainted 4.14.77+ #21
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5 D28408 31196 1847 0x00000004
Call Trace:
schedule+0x7f/0x1b0 kernel/sched/core.c:3490
__rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:565 [inline]
rwsem_down_write_failed+0x390/0x730 kernel/locking/rwsem-xadd.c:594
call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:105
__down_write arch/x86/include/asm/rwsem.h:126 [inline]
down_write+0x4f/0x90 kernel/locking/rwsem.c:56
inode_lock include/linux/fs.h:713 [inline]
do_last fs/namei.c:3317 [inline]
path_openat+0xe43/0x23a0 fs/namei.c:3550
do_filp_open+0x197/0x270 fs/namei.c:3584
do_sys_open+0x2ef/0x580 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x457569
RSP: 002b:00007f9b75ee5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000457569
RDX: 0000000000000000 RSI: 0000000000000060 RDI: 0000000020000340
RBP: 000000000072c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9b75ee66d4
R13: 00000000004bdb2f R14: 00000000004cc688 R15: 00000000ffffffff
INFO: task syz-executor5:31198 blocked for more than 140 seconds.
Not tainted 4.14.77+ #21
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5 D29160 31198 1847 0x00000004
Call Trace:
schedule+0x7f/0x1b0 kernel/sched/core.c:3490
__rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:565 [inline]
rwsem_down_write_failed+0x390/0x730 kernel/locking/rwsem-xadd.c:594
call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:105
__down_write arch/x86/include/asm/rwsem.h:126 [inline]
down_write+0x4f/0x90 kernel/locking/rwsem.c:56
inode_lock include/linux/fs.h:713 [inline]
do_last fs/namei.c:3317 [inline]
path_openat+0xe43/0x23a0 fs/namei.c:3550
do_filp_open+0x197/0x270 fs/namei.c:3584
do_sys_open+0x2ef/0x580 fs/open.c:1071
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x457569
RSP: 002b:00007f9b75ec4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000457569
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000700
RBP: 000000000072c0e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9b75ec56d4
R13: 00000000004bdb2f R14: 00000000004cc688 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/23:
#0: (tasklist_lock){.+.+}, at: [<ffffffffa9802247>]
debug_show_all_locks+0x74/0x20f kernel/locking/lockdep.c:4541
2 locks held by getty/1762:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffffaa32f730>]
tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffffaa32acaf>]
n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor4/7156:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffffaa32f730>]
tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffffaa32acaf>]
n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor3/13522:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffffaa32f730>]
tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffffaa32acaf>]
n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor5/31196:
#0: (sb_writers#4){.+.+}, at: [<ffffffffa9bc5c9a>] sb_start_write
include/linux/fs.h:1543 [inline]
#0: (sb_writers#4){.+.+}, at: [<ffffffffa9bc5c9a>]
mnt_want_write+0x3a/0xa0 fs/namespace.c:387
#1: (&type->i_mutex_dir_key#3){++++}, at: [<ffffffffa9b8c403>] inode_lock
include/linux/fs.h:713 [inline]
#1: (&type->i_mutex_dir_key#3){++++}, at: [<ffffffffa9b8c403>] do_last
fs/namei.c:3317 [inline]
#1: (&type->i_mutex_dir_key#3){++++}, at: [<ffffffffa9b8c403>]
path_openat+0xe43/0x23a0 fs/namei.c:3550
2 locks held by syz-executor5/31198:
#0: (sb_writers#4){.+.+}, at: [<ffffffffa9bc5c9a>] sb_start_write
include/linux/fs.h:1543 [inline]
#0: (sb_writers#4){.+.+}, at: [<ffffffffa9bc5c9a>]
mnt_want_write+0x3a/0xa0 fs/namespace.c:387
#1: (&type->i_mutex_dir_key#3){++++}, at: [<ffffffffa9b8c403>] inode_lock
include/linux/fs.h:713 [inline]
#1: (&type->i_mutex_dir_key#3){++++}, at: [<ffffffffa9b8c403>] do_last
fs/namei.c:3317 [inline]
#1: (&type->i_mutex_dir_key#3){++++}, at: [<ffffffffa9b8c403>]
path_openat+0xe43/0x23a0 fs/namei.c:3550

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

NMI backtrace for cpu 0
CPU: 0 PID: 23 Comm: khungtaskd Not tainted 4.14.77+ #21
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0xb9/0x11b lib/dump_stack.c:53
nmi_cpu_backtrace.cold.0+0x47/0x85 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x121/0x146 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline]
watchdog+0x574/0xa70 kernel/hung_task.c:252
kthread+0x348/0x420 kernel/kthread.c:232
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffffaae56742


---
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#status for how to communicate with syzbot.

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 71fce1ed UPSTREAM: tracing: always define trace_{irq,preem..
git tree: android-4.9
console output: https://syzkaller.appspot.com/x/log.txt?x=118d8c07800000
kernel config: https://syzkaller.appspot.com/x/.config?x=a54f56879744de40
dashboard link: https://syzkaller.appspot.com/bug?extid=8a9b4b3a7431fa6d9f84

compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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+8a9b4b...@syzkaller.appspotmail.com

b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
INFO: task syz-executor0:12689 blocked for more than 120 seconds.
Not tainted 4.9.96-g71fce1e #10

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

syz-executor0 D29816 12689 3873 0x00000004
ffff8801d7908000 ffff8801bdacb480 ffff8801c02739c0 ffff8801d5368000
ffff8801db321b98 ffff8801d49f78b0 ffffffff839e240d ffffffff81233817
0000000000000000 ffff8801d79088c0 0000000600000007 ffff8801db322468
Call Trace:
[<ffffffff839e3a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
[<ffffffff839ede34>] rwsem_down_read_failed+0x1e4/0x320
kernel/locking/rwsem-xadd.c:260
[<ffffffff81ee4e48>] call_rwsem_down_read_failed+0x18/0x30
arch/x86/lib/rwsem.S:94
[<ffffffff839ecd62>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
[<ffffffff839ecd62>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
[<ffffffff815a2f2c>] inode_lock_shared include/linux/fs.h:776 [inline]
[<ffffffff815a2f2c>] do_last fs/namei.c:3314 [inline]
[<ffffffff815a2f2c>] path_openat+0x17dc/0x3590 fs/namei.c:3534
[<ffffffff815a8fa7>] do_filp_open+0x197/0x270 fs/namei.c:3568
[<ffffffff8156b77d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
[<ffffffff8156ba5d>] SYSC_open fs/open.c:1090 [inline]
[<ffffffff8156ba5d>] SyS_open+0x2d/0x40 fs/open.c:1085
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839f3313>] 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: [<ffffffff813646ec>]
check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
#0: (rcu_read_lock){......}, at: [<ffffffff813646ec>]
watchdog+0x11c/0xa20 kernel/hung_task.c:239
#1: (tasklist_lock){.+.+..}, at: [<ffffffff81423ce0>]
debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3673:
#0: (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d579c>]
__fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3769:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f14b2>]
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211c792>]
n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
2 locks held by syz-executor0/12689:
#0: (sb_writers#12){.+.+.+}, at: [<ffffffff815de03f>] sb_start_write
include/linux/fs.h:1573 [inline]
#0: (sb_writers#12){.+.+.+}, at: [<ffffffff815de03f>]
mnt_want_write+0x3f/0xb0 fs/namespace.c:391
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2f2c>]
inode_lock_shared include/linux/fs.h:776 [inline]
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2f2c>]
do_last fs/namei.c:3314 [inline]
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2f2c>]
path_openat+0x17dc/0x3590 fs/namei.c:3534
2 locks held by syz-executor0/12694:
#0: (sb_writers#12){.+.+.+}, at: [<ffffffff815de03f>] sb_start_write
include/linux/fs.h:1573 [inline]
#0: (sb_writers#12){.+.+.+}, at: [<ffffffff815de03f>]
mnt_want_write+0x3f/0xb0 fs/namespace.c:391
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2625>]
inode_lock include/linux/fs.h:766 [inline]
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2625>]
do_last fs/namei.c:3312 [inline]
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2625>]
path_openat+0xed5/0x3590 fs/namei.c:3534
2 locks held by syz-executor0/12701:
#0: (sb_writers#12){.+.+.+}, at: [<ffffffff815de03f>] sb_start_write
include/linux/fs.h:1573 [inline]
#0: (sb_writers#12){.+.+.+}, at: [<ffffffff815de03f>]
mnt_want_write+0x3f/0xb0 fs/namespace.c:391
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2f2c>]
inode_lock_shared include/linux/fs.h:776 [inline]
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2f2c>]
do_last fs/namei.c:3314 [inline]
#1: (&sb->s_type->i_mutex_key#15){+++++.}, at: [<ffffffff815a2f2c>]
path_openat+0x17dc/0x3590 fs/namei.c:3534

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

NMI backtrace for cpu 1
CPU: 1 PID: 518 Comm: khungtaskd Not tainted 4.9.96-g71fce1e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
ffff8801d863fd08 ffffffff81eb0b69 0000000000000000 0000000000000001
0000000000000001 0000000000000001 ffffffff810b7d60 ffff8801d863fd40
ffffffff81ebbe97 0000000000000001 0000000000000000 0000000000000003
Call Trace:
[<ffffffff81eb0b69>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81eb0b69>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff81ebbe97>] nmi_cpu_backtrace.cold.2+0x48/0x87
lib/nmi_backtrace.c:99
[<ffffffff81ebbe2a>] 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
[<ffffffff81364c84>] trigger_all_cpu_backtrace include/linux/nmi.h:58
[inline]
[<ffffffff81364c84>] check_hung_task kernel/hung_task.c:125 [inline]
[<ffffffff81364c84>] check_hung_uninterruptible_tasks
kernel/hung_task.c:182 [inline]
[<ffffffff81364c84>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
[<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
[<ffffffff839f34dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:

NMI backtrace for cpu 0

CPU: 0 PID: 12687 Comm: syz-executor2 Not tainted 4.9.96-g71fce1e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8801d790e000 task.stack: ffff8801ba380000
RIP: 0010:[<ffffffff8214d0fb>] c [<ffffffff8214d0fb>] inb
arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff8214d0fb>] c [<ffffffff8214d0fb>]
io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0018:ffff8801ba3874e8 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff8214d0a1 RDI: ffffffff862aae78
RBP: ffff8801ba3874f8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff862aae40
R13: 0000000000000020 R14: fffffbfff0c5560f R15: fffffbfff0c555d1
FS: 00007f521ebd5700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c42663d000 CR3: 00000001cc40e000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
ffffffff862aae40 c 000000000000270a c ffff8801ba387548 c ffffffff8214ecc4 c
ffffffff81edbe88 c ffffffff862aae88 c ffffffff862ab07a c ffffffff862aae40 c
0000000000000067 c ffffffff8214ee10 c dffffc0000000000 c 0000000000000067 c
Call Trace:
[<ffffffff8214ecc4>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
[<ffffffff8214ecc4>] wait_for_xmitr+0x94/0x1e0
drivers/tty/serial/8250/8250_port.c:1997
[<ffffffff8214ee2f>] serial8250_console_putchar+0x1f/0x60
drivers/tty/serial/8250/8250_port.c:3103
[<ffffffff82137659>] uart_console_write+0x59/0xf0
drivers/tty/serial/serial_core.c:1859
[<ffffffff8215b038>] serial8250_console_write+0x528/0x820
drivers/tty/serial/8250/8250_port.c:3169
[<ffffffff82147baf>] univ8250_console_write+0x5f/0x70
drivers/tty/serial/8250/8250_core.c:594
[<ffffffff81259e7d>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360
kernel/printk/printk.c:1589
[<ffffffff8125cc7f>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
[<ffffffff8125d7d8>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1903
[<ffffffff8125db48>] vprintk+0x28/0x30 kernel/printk/printk.c:1913
[<ffffffff8125db6d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1914
[<ffffffff8142aab5>] vprintk_func kernel/printk/internal.h:36 [inline]
[<ffffffff8142aab5>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
[<ffffffff81cb9046>] __ext4_warning.cold.131+0x51/0x56 fs/ext4/super.c:664
[<ffffffff817dfd90>] ext4_resize_begin+0x1b0/0x1e0 fs/ext4/resize.c:43
[<ffffffff81762b76>] ext4_ioctl+0x1166/0x3620 fs/ext4/ioctl.c:713
[<ffffffff815b051c>] vfs_ioctl fs/ioctl.c:43 [inline]
[<ffffffff815b051c>] file_ioctl fs/ioctl.c:493 [inline]
[<ffffffff815b051c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
[<ffffffff815b159f>] SYSC_ioctl fs/ioctl.c:694 [inline]
[<ffffffff815b159f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839f3313>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: c24 cc9 c00 c00 c00 c49 c8d c7c c24 c38 c48 cb8 c00 c00
c00 c00 c00 cfc cff cdf c48 c89 cfa c48 cc1 cea c03 cd3 ce3
c80 c3c c02 c00 c75 c17 c41 c03 c5c c24 c38 c89 cda cec
c<5b> c0f cb6 cc0 c41 c5c c5d cc3 ce8 c18 cc3 c3e cff ceb
cc2 ce8 c71 cc3 c3e cff ceb c

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.

[syzbot]