INFO: task hung in xlog_grant_head_check (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 76567537 Linux 4.19.119
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13dd824c100000
kernel config: https://syzkaller.appspot.com/x/.config?x=dd6adfe2dd5d771
dashboard link: https://syzkaller.appspot.com/bug?extid=5f479e9a7382b68cc463
compiler: gcc (GCC) 9.0.0 20181231 (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+5f479e...@syzkaller.appspotmail.com

INFO: task syz-executor.4:22571 blocked for more than 140 seconds.
Not tainted 4.19.119-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D26960 22571 6794 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3559
xlog_grant_head_wait+0x150/0xce0 fs/xfs/xfs_log.c:263
xlog_grant_head_check+0x3b9/0x410 fs/xfs/xfs_log.c:325
xfs_log_reserve+0x344/0xa80 fs/xfs/xfs_log.c:454
xfs_log_write_unmount_record fs/xfs/xfs_log.c:854 [inline]
xfs_log_unmount_write fs/xfs/xfs_log.c:953 [inline]
xfs_log_quiesce+0x3e5/0xc00 fs/xfs/xfs_log.c:1020
xfs_log_unmount+0x1d/0xb0 fs/xfs/xfs_log.c:1034
xfs_log_mount_cancel+0x40/0x50 fs/xfs/xfs_log.c:816
xfs_mountfs+0x12ce/0x1bd0 fs/xfs/xfs_mount.c:1064
xfs_fs_fill_super+0xd0e/0x1530 fs/xfs/xfs_super.c:1720
mount_bdev+0x305/0x3c0 fs/super.c:1158
mount_fs+0xa3/0x30c fs/super.c:1261
vfs_kern_mount.part.0+0x68/0x400 fs/namespace.c:961
vfs_kern_mount fs/namespace.c:951 [inline]
do_new_mount fs/namespace.c:2469 [inline]
do_mount+0x4f4/0x2a40 fs/namespace.c:2799
ksys_mount+0xd7/0x150 fs/namespace.c:3015
__do_sys_mount fs/namespace.c:3029 [inline]
__se_sys_mount fs/namespace.c:3026 [inline]
__x64_sys_mount+0xba/0x150 fs/namespace.c:3026
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45f27a
Code: Bad RIP value.
RSP: 002b:00007fe5de806a68 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00000000005087c0 RCX: 000000000045f27a
RDX: 00007fe5de806ae0 RSI: 0000000020000140 RDI: 00007fe5de806b00
RBP: 000000000078bf00 R08: 00007fe5de806b40 R09: 00007fe5de806ae0
R10: 0000000000000000 R11: 0000000000000206 R12: 00000000ffffffff
R13: 0000000000000bf2 R14: 00000000004ce170 R15: 00007fe5de8076d4

Showing all locks held in the system:
1 lock held by khungtaskd/1071:
#0: 000000003fa6ed1e (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
2 locks held by systemd-journal/3682:
1 lock held by syz-executor.4/22571:
#0: 000000004035911e (&type->s_umount_key#75/1){+.+.}, at: alloc_super fs/super.c:226 [inline]
#0: 000000004035911e (&type->s_umount_key#75/1){+.+.}, at: sget_userns+0x1fc/0xcd0 fs/super.c:519

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

NMI backtrace for cpu 0
CPU: 0 PID: 1071 Comm: khungtaskd Not tainted 4.19.119-syzkaller #0
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+0x188/0x20d lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
watchdog+0x962/0xe40 kernel/hung_task.c:287
kthread+0x34a/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 15168 Comm: syz-executor.3 Not tainted 4.19.119-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:check_memory_region+0xb6/0x180 mm/kasan/kasan.c:268
Code: 08 4c 39 c0 0f 84 87 00 00 00 48 83 38 00 74 ed 4c 8d 40 08 eb 09 48 83 c0 01 49 39 c0 74 0a 80 38 00 74 f2 48 85 c0 75 5a 5b <5d> 41 5c c3 41 bc 08 00 00 00 45 29 c4 49 89 d8 4d 8d 0c 1c eb 0c
RSP: 0000:ffff88808fb47a88 EFLAGS: 00000046
RAX: fffffbfff168a0e6 RBX: 0000000000000000 RCX: ffffffff814f745b
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8b450728
RBP: fffffbfff168a0e6 R08: 0000000000000001 R09: fffffbfff168a0e6
R10: fffffbfff168a0e5 R11: ffffffff8b45072b R12: 0000000000000001
R13: 0000000000000000 R14: ffff88803bfe4140 R15: ffff888084df6488
FS: 00007f888cbbe700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000053c0e7a0 CR3: 000000008ec44000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
atomic_inc include/asm-generic/atomic-instrumented.h:109 [inline]
__lock_acquire+0x23b/0x49c0 kernel/locking/lockdep.c:3307
lock_acquire+0x170/0x400 kernel/locking/lockdep.c:3907
__might_fault mm/memory.c:4638 [inline]
__might_fault+0x152/0x1d0 mm/memory.c:4623
__copy_to_user include/linux/uaccess.h:102 [inline]
__setup_rt_frame arch/x86/kernel/signal.c:496 [inline]
setup_rt_frame arch/x86/kernel/signal.c:711 [inline]
handle_signal arch/x86/kernel/signal.c:755 [inline]
do_signal+0xe03/0x1710 arch/x86/kernel/signal.c:823
exit_to_usermode_loop+0x22b/0x2b0 arch/x86/entry/common.c:163
prepare_exit_to_usermode+0x27b/0x2e0 arch/x86/entry/common.c:198
retint_user+0x8/0x18
RIP: 0033:0x405be9
Code: d0 ff ff ff 01 48 8b 7c 24 28 c7 44 24 34 00 00 00 00 e8 ba ee 01 00 85 c0 75 23 48 6b 44 24 20 18 8b 7c 24 1c 48 03 44 24 38 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 57 0a 01 00 89 44 24 34 64 f0
RSP: 002b:00007f888cbbda70 EFLAGS: 00010206
RAX: 0000000053c0e790 RBX: 0000000000508780 RCX: 0000000000416687
RDX: cf7b95bc6b1e83f5 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 000000000078c0e0 R08: 00007f888cbbda70 R09: 000000000078c0e0
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000bf1 R14: 00000000004ce15b R15: 00007f888cbbe6d4


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[syzbot]

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