INFO: task hung in __sync_dirty

INFO: task hung in __sync_dirty_buffer
Status: upstream: reported C repro on 2021/09/01 20:17
Reported-by: syzbot+91dccab7c64e2850a4e5@syzkaller.appspotmail.com
First crash: 56d, last: 23d

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: INFO: task hung in __sync_dirty_buffer (log)
Repro: C syz .config

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	INFO: task hung in __sync_dirty_buffer	C			3	29d	390d	0/1	upstream: reported C repro on 2020/09/29 05:34
linux-4.19	INFO: task hung in __sync_dirty_buffer	C		error	4	33d	378d	0/1	upstream: reported C repro on 2020/10/11 09:03

Sample crash report:

INFO: task syz-executor409:8464 blocked for more than 143 seconds.
      Not tainted 5.14.0-rc7-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor409 state:D stack:25624 pid: 8464 ppid:  8463 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4681 [inline]
 __schedule+0x93a/0x26f0 kernel/sched/core.c:5938
 schedule+0xd3/0x270 kernel/sched/core.c:6017
 io_schedule+0xba/0x130 kernel/sched/core.c:7988
 bit_wait_io+0x12/0xd0 kernel/sched/wait_bit.c:209
 __wait_on_bit_lock+0x121/0x1a0 kernel/sched/wait_bit.c:90
 out_of_line_wait_on_bit_lock+0xd5/0x110 kernel/sched/wait_bit.c:117
 wait_on_bit_lock_io include/linux/wait_bit.h:208 [inline]
 __lock_buffer fs/buffer.c:69 [inline]
 lock_buffer include/linux/buffer_head.h:368 [inline]
 __sync_dirty_buffer+0x363/0x3f0 fs/buffer.c:3138
 __ext4_handle_dirty_metadata+0x28f/0x720 fs/ext4/ext4_jbd2.c:361
 ext4_convert_inline_data_nolock+0x67a/0xf30 fs/ext4/inline.c:1237
 ext4_convert_inline_data+0x31a/0x490 fs/ext4/inline.c:1990
 ext4_fallocate+0x1ae/0x3ff0 fs/ext4/extents.c:4666
 vfs_fallocate+0x48d/0xd80 fs/open.c:311
 ksys_fallocate fs/open.c:334 [inline]
 __do_sys_fallocate fs/open.c:342 [inline]
 __se_sys_fallocate fs/open.c:340 [inline]
 __x64_sys_fallocate+0xcf/0x140 fs/open.c:340
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x444b09
RSP: 002b:00007fff1122eaa8 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00000000004004a0 RCX: 0000000000444b09
RDX: 0000000000000000 RSI: 0000000100000001 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: 000000002811fdff R11: 0000000000000246 R12: 00007fff1122ead0
R13: 0000000000000000 R14: 431bde82d7b634db R15: 00000000004004a0

Showing all locks held in the system:
1 lock held by khungtaskd/1654:
 #0: ffffffff8b97c280 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6446
2 locks held by syz-executor409/8464:
 #0: ffff88802f05a460 (sb_writers#5){.+.+}-{0:0}, at: ksys_fallocate fs/open.c:334 [inline]
 #0: ffff88802f05a460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_fallocate fs/open.c:342 [inline]
 #0: ffff88802f05a460 (sb_writers#5){.+.+}-{0:0}, at: __se_sys_fallocate fs/open.c:340 [inline]
 #0: ffff88802f05a460 (sb_writers#5){.+.+}-{0:0}, at: __x64_sys_fallocate+0xcf/0x140 fs/open.c:340
 #1: ffff8880379ea8a8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:142 [inline]
 #1: ffff8880379ea8a8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_convert_inline_data+0x21e/0x490 fs/ext4/inline.c:1988

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

NMI backtrace for cpu 0
CPU: 0 PID: 1654 Comm: khungtaskd Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
 watchdog+0xd0a/0xfc0 kernel/hung_task.c:295
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8471 Comm: kworker/u4:0 Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:kasan_check_range+0x15/0x180 mm/kasan/generic.c:188
Code: 39 02 0f 1f 00 48 89 f2 be f8 00 00 00 e9 a3 aa 39 02 0f 1f 00 48 85 f6 0f 84 70 01 00 00 49 89 f9 41 54 44 0f b6 c2 49 01 f1 <55> 53 0f 82 18 01 00 00 48 b8 ff ff ff ff ff 7f ff ff 48 39 c7 0f
RSP: 0018:ffffc900015af948 EFLAGS: 00000286
RAX: 0000000000000000 RBX: 1ffff920002b5f2d RCX: ffffffff815b2948
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8d6c81d0
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8d6c81d8
R10: ffffffff819871c0 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8b847e48 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd7c14da000 CR3: 000000000b68e000 CR4: 0000000000350ee0
Call Trace:
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
 cpumask_test_cpu include/linux/cpumask.h:344 [inline]
 cpu_online include/linux/cpumask.h:895 [inline]
 trace_lock_acquire include/trace/events/lock.h:13 [inline]
 lock_acquire+0xb8/0x510 kernel/locking/lockdep.c:5596
 __mutex_lock_common kernel/locking/mutex.c:959 [inline]
 __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
 arch_jump_label_transform_queue+0x58/0x100 arch/x86/kernel/jump_label.c:136
 __jump_label_update+0x12e/0x400 kernel/jump_label.c:451
 jump_label_update+0x1d5/0x430 kernel/jump_label.c:830
 static_key_disable_cpuslocked+0x152/0x1b0 kernel/jump_label.c:207
 static_key_disable+0x16/0x20 kernel/jump_label.c:215
 toggle_allocation_gate mm/kfence/core.c:637 [inline]
 toggle_allocation_gate+0x185/0x390 mm/kfence/core.c:615
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
----------------
Code disassembly (best guess):
   0:	39 02                	cmp    %eax,(%rdx)
   2:	0f 1f 00             	nopl   (%rax)
   5:	48 89 f2             	mov    %rsi,%rdx
   8:	be f8 00 00 00       	mov    $0xf8,%esi
   d:	e9 a3 aa 39 02       	jmpq   0x239aab5
  12:	0f 1f 00             	nopl   (%rax)
  15:	48 85 f6             	test   %rsi,%rsi
  18:	0f 84 70 01 00 00    	je     0x18e
  1e:	49 89 f9             	mov    %rdi,%r9
  21:	41 54                	push   %r12
  23:	44 0f b6 c2          	movzbl %dl,%r8d
  27:	49 01 f1             	add    %rsi,%r9
* 2a:	55                   	push   %rbp <-- trapping instruction
  2b:	53                   	push   %rbx
  2c:	0f 82 18 01 00 00    	jb     0x14a
  32:	48 b8 ff ff ff ff ff 	movabs $0xffff7fffffffffff,%rax
  39:	7f ff ff
  3c:	48 39 c7             	cmp    %rax,%rdi
  3f:	0f                   	.byte 0xf

Fix bisection attempts:
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-kasan-gce-root	2021/10/01 11:08	upstream	4de593fb965f	be2c130d	.config	log	report	syz	C

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-kasan-gce-root	2021/08/28 20:15	upstream	64b4fc45bea6	be2c130d	.config	log	report	syz	C		INFO: task hung in __sync_dirty_buffer
ci-upstream-linux-next-kasan-gce-root	2021/08/31 20:01	linux-next	52c7b727581f	7eb7e152	.config	log	report			info	INFO: task hung in __sync_dirty_buffer