INFO: task can't die in iget5

INFO: task can't die in iget5_locked
Status: fixed on 2021/04/09 19:46
Reported-by: syzbot+1732f7c4545ff63c9119@syzkaller.appspotmail.com
Fix commit: 775c5033a0d1 fuse: fix live lock in fuse_iget()
First crash: 249d, last: 205d

similar bugs (5):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	INFO: task hung in chown_common (3)				11	209d	260d	0/22	auto-closed as invalid on 2021/05/20 23:06
linux-4.19	INFO: task hung in lock_mount (4)				3	23d	55d	0/1	upstream: reported on 2021/07/24 02:18
upstream	INFO: task can't die in lock_mount				73	198d	272d	0/22	closed as dup on 2021/01/18 10:01
upstream	INFO: task hung in lock_mount	C	error	error	1225	17d	1236d	0/22	upstream: reported C repro on 2018/04/30 17:46
linux-4.19	INFO: task hung in lock_mount (3)				1	220d	220d	0/1	auto-closed as invalid on 2021/06/09 16:09

Sample crash report:

INFO: task syz-executor.0:11059 can't die for more than 143 seconds.
task:syz-executor.0  state:R  running task     stack:27080 pid:11059 ppid:  8451 flags:0x00004006
Call Trace:
 context_switch kernel/sched/core.c:4324 [inline]
 __schedule+0x90c/0x21a0 kernel/sched/core.c:5075
 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:5235
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:183
 ilookup5_nowait fs/inode.c:1335 [inline]
 ilookup5 fs/inode.c:1364 [inline]
 iget5_locked+0xbd/0x2e0 fs/inode.c:1145
 fuse_iget+0x271/0x610 fs/fuse/inode.c:342
 fuse_lookup_name+0x447/0x630 fs/fuse/dir.c:439
 fuse_lookup.part.0+0xdf/0x390 fs/fuse/dir.c:469
 fuse_lookup+0x70/0x90 fs/fuse/dir.c:465
 __lookup_hash+0x117/0x180 fs/namei.c:1527
 filename_create+0x186/0x490 fs/namei.c:3597
 user_path_create fs/namei.c:3654 [inline]
 do_mkdirat+0xa0/0x310 fs/namei.c:3832
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x465007
RSP: 002b:00007f04d7c02fa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000465007
RDX: 0000000000000000 RSI: 00000000000001ff RDI: 0000000020000080
RBP: 00007f04d7c03040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000020000080 R14: 00007f04d7c03000 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1640:
 #0: ffffffff8bf744a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6327
1 lock held by in:imklog/8138:
 #0: ffff888021ec9c70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:961
4 locks held by syz-executor.0/11059:

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

Crashes (7):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci-upstream-linux-next-kasan-gce-root	2021/02/24 14:59	linux-next	577c283560fe	fcc6d71b	.config	log	report	info	INFO: task can't die in iget5_locked
ci-upstream-linux-next-kasan-gce-root	2021/02/07 13:03	linux-next	aa2b88209686	2ce644fc	.config	log	report	info	INFO: task can't die in iget5_locked
ci-upstream-linux-next-kasan-gce-root	2021/01/31 09:38	linux-next	b01f250d83f6	fc9fd31e	.config	log	report	info	INFO: task can't die in iget5_locked
ci-upstream-linux-next-kasan-gce-root	2021/01/30 22:06	linux-next	b01f250d83f6	fc9fd31e	.config	log	report	info	INFO: task can't die in iget5_locked
ci-upstream-linux-next-kasan-gce-root	2021/01/28 14:54	linux-next	d03154e8bb6a	eefc07f2	.config	log	report	info	INFO: task can't die in iget5_locked
ci-upstream-linux-next-kasan-gce-root	2021/01/28 04:25	linux-next	bc085f8fc88f	eefc07f2	.config	log	report	info	INFO: task can't die in iget5_locked
ci-upstream-linux-next-kasan-gce-root	2021/01/11 02:54	linux-next	1c925d2030af	2c1f2513	.config	log	report	info