INFO: task hung in xlog_grant_head

INFO: task hung in xlog_grant_head_check (2)
Status: auto-closed as invalid on 2020/10/17 16:39
Reported-by: syzbot+5f479e9a7382b68cc463@syzkaller.appspotmail.com
First crash: 301d, last: 252d

similar bugs (3):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	INFO: task hung in xlog_grant_head_check	C		inconclusive	7	229d	383d	0/1	upstream: reported C repro on 2020/02/10 12:53
upstream	INFO: task hung in xlog_grant_head_check	C	done	error	37	226d	1012d	0/21	upstream: reported C repro on 2018/05/21 17:55
linux-4.19	INFO: task hung in xlog_grant_head_check				1	612d	611d	0/1	auto-closed as invalid on 2019/10/25 08:51

Sample crash report:

XFS (loop4): Filesystem has a realtime volume, use rtdev=device option
XFS (loop4): RT mount failed
XFS (loop2): Filesystem has a realtime volume, use rtdev=device option
XFS (loop2): RT mount failed
INFO: task syz-executor.0:22860 blocked for more than 140 seconds.
      Not tainted 4.19.128-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D26720 22860   6460 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2826 [inline]
 __schedule+0x8a2/0x1fc0 kernel/sched/core.c:3515
 schedule+0x8d/0x1b0 kernel/sched/core.c:3559
 xlog_grant_head_wait+0x143/0xce0 fs/xfs/xfs_log.c:263
 xlog_grant_head_check+0x3b9/0x410 fs/xfs/xfs_log.c:325
 xfs_log_reserve+0x345/0xa70 fs/xfs/xfs_log.c:454
 xfs_log_write_unmount_record+0x154/0x870 fs/xfs/xfs_log.c:854
 xfs_log_unmount_write fs/xfs/xfs_log.c:953 [inline]
 xfs_log_quiesce+0x4a4/0x570 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+0x12c1/0x1bc0 fs/xfs/xfs_mount.c:1064
 xfs_fs_fill_super+0xd03/0x1530 fs/xfs/xfs_super.c:1720
 mount_bdev+0x2fc/0x3b0 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+0x4f4/0x2b50 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: 0033:0x45f4aa
Code: 00 75 91 c6 84 24 48 01 00 00 00 48 8b ac 24 20 01 00 00 48 81 c4 28 01 00 00 c3 c6 84 24 48 01 00 00 01 48 8b ac 24 20 01 00 <00> 48 81 c4 28 01 00 00 c3 b8 38 00 00 00 e9 02 ff ff ff b8 38 00
RSP: 002b:00007f4b90c38a68 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000509a20 RCX: 000000000045f4aa
RDX: 00007f4b90c38ae0 RSI: 0000000020000080 RDI: 00007f4b90c38b00
RBP: 000000000078bf00 R08: 00007f4b90c38b40 R09: 00007f4b90c38ae0
R10: 0000000000000000 R11: 0000000000000206 R12: 00000000ffffffff
R13: 0000000000000c1e R14: 00000000004ce6db R15: 00007f4b90c396d4

Showing all locks held in the system:
1 lock held by khungtaskd/1083:
 #0: 0000000054c3cba9 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/6131:
 #0: 00000000d725864f (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:767
1 lock held by syz-executor.0/22860:
 #0: 0000000015dc6fde (&type->s_umount_key#69/1){+.+.}, at: alloc_super fs/super.c:226 [inline]
 #0: 0000000015dc6fde (&type->s_umount_key#69/1){+.+.}, at: sget_userns+0x1fc/0xcd0 fs/super.c:519

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

NMI backtrace for cpu 1
CPU: 1 PID: 1083 Comm: khungtaskd Not tainted 4.19.128-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+0x1fc/0x2fe 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+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10 Comm: rcu_preempt Not tainted 4.19.128-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__hlist_del include/linux/list.h:680 [inline]
RIP: 0010:detach_timer kernel/time/timer.c:817 [inline]
RIP: 0010:detach_if_pending+0x12f/0x460 kernel/time/timer.c:834
Code: 03 80 3c 02 00 0f 85 0b 03 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 08 4c 89 e2 48 c1 ea 03 80 3c 02 00 0f 85 f9 02 00 00 <48> 85 ed 49 89 2c 24 74 28 e8 43 ae 0e 00 48 8d 7d 08 48 b8 00 00
RSP: 0018:ffff8880a9eafb18 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffff8880a9eafc70 RCX: ffffffff8158eea6
RDX: 1ffff11015cc4788 RSI: ffffffff8158ec17 RDI: 0000000000000001
RBP: ffffffff89087aa0 R08: ffff8880a9e96280 R09: ffffed1015cc473b
R10: ffffed1015cc473a R11: ffff8880ae6239d3 R12: ffff8880ae623c40
R13: 0000000000000001 R14: ffff8880a9eafc78 R15: 00000000ffffffff
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2f46564018 CR3: 0000000093c99000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 try_to_del_timer_sync+0xaa/0x110 kernel/time/timer.c:1228
 del_timer_sync+0x1a4/0x270 kernel/time/timer.c:1293
 schedule_timeout+0x4c9/0xed0 kernel/time/timer.c:1807
 rcu_gp_kthread+0xf94/0x2050 kernel/rcu/tree.c:2202
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci2-linux-4-19	2020/06/19 16:38	linux-4.19.y	3fc89857	123cf502	.config	log	report
ci2-linux-4-19	2020/05/03 21:44	linux-4.19.y	fdc07232	58ae5e18	.config	log	report
ci2-linux-4-19	2020/05/02 03:08	linux-4.19.y	76567537	bc734e7a	.config	log	report