[v6.1] INFO: task hung in migrate_pages

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syzbot

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Oct 9, 2023, 5:51:57 AM10/9/23
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Hello,

syzbot found the following issue on:

HEAD commit: ecda77b46871 Linux 6.1.56
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15a813ee680000
kernel config: https://syzkaller.appspot.com/x/.config?x=e82fa6f6f9ab7d72
dashboard link: https://syzkaller.appspot.com/bug?extid=da6bca601b02839466f1
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0b7814b5111f/disk-ecda77b4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f23a3c686699/vmlinux-ecda77b4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/474cde37da7a/bzImage-ecda77b4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+da6bca...@syzkaller.appspotmail.com

INFO: task kcompactd0:31 blocked for more than 143 seconds.
Not tainted 6.1.56-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kcompactd0 state:D stack:24544 pid:31 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6554
schedule+0xbf/0x180 kernel/sched/core.c:6630
io_schedule+0x88/0x100 kernel/sched/core.c:8782
folio_wait_bit_common+0x878/0x1290 mm/filemap.c:1296
__unmap_and_move mm/migrate.c:1032 [inline]
unmap_and_move mm/migrate.c:1186 [inline]
migrate_pages+0xaa7/0x4070 mm/migrate.c:1463
compact_zone+0x2aef/0x41e0 mm/compaction.c:2414
proactive_compact_node mm/compaction.c:2666 [inline]
kcompactd+0x1862/0x28e0 mm/compaction.c:2976
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
INFO: task syz-executor.2:9153 blocked for more than 143 seconds.
Not tainted 6.1.56-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.2 state:D stack:26936 pid:9153 ppid:469 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6554
schedule+0xbf/0x180 kernel/sched/core.c:6630
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6689
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
blkdev_put+0x100/0x750 block/bdev.c:911
blkdev_close+0x56/0x80 block/fops.c:514
__fput+0x3b7/0x890 fs/file_table.c:320
task_work_run+0x246/0x300 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:171
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:297
do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f1a39a7cae9
RSP: 002b:00007f1a3a8260c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007f1a39b9bf80 RCX: 00007f1a39a7cae9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007f1a39ac847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f1a39b9bf80 R15: 00007ffd6feb6578
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8d12a170 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8d12a970 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
1 lock held by khungtaskd/28:
#0: ffffffff8d129fa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:306 [inline]
#0: ffffffff8d129fa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#0: ffffffff8d129fa0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6493
2 locks held by kworker/u4:2/38:
#0: ffff8880b9939e18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
#1: ffff8880b9927788 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x3a3/0x770 kernel/sched/psi.c:988
2 locks held by getty/3305:
#0: ffff888027f7e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc900031262f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a7/0x1db0 drivers/tty/n_tty.c:2188
4 locks held by kworker/u4:24/4053:
#0: ffff8880b9939e18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
#1: ffff8880b9927788 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x43d/0x770 kernel/sched/psi.c:1000
#2: ffff888098554d40 (&wdev->mtx){+.+.}-{3:3}, at: sdata_lock net/mac80211/ieee80211_i.h:1114 [inline]
#2: ffff888098554d40 (&wdev->mtx){+.+.}-{3:3}, at: ieee80211_ibss_work+0xa0/0x1480 net/mac80211/ibss.c:1680
#3: ffffffff8d129fa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:306 [inline]
#3: ffffffff8d129fa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#3: ffffffff8d129fa0 (rcu_read_lock){....}-{1:2}, at: ieee80211_sta_active_ibss+0xb1/0x310 net/mac80211/ibss.c:654
1 lock held by udevd/11308:
#0: ffff88801f3574c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa10 block/bdev.c:813
1 lock held by syz-executor.2/9153:
#0: ffff88801f3574c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x100/0x750 block/bdev.c:911
1 lock held by syz-executor.2/9256:
#0: ffff88801f3574c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa10 block/bdev.c:813
1 lock held by syz-executor.2/9321:
#0: ffff88801f3574c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x148/0xa10 block/bdev.c:813

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.1.56-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1b0/0x3f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
watchdog+0xf88/0xfd0 kernel/hung_task.c:377
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 38 Comm: kworker/u4:2 Not tainted 6.1.56-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: bat_events batadv_nc_worker
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:228 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:240 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:__lock_acquire+0xcc9/0x1f80 kernel/locking/lockdep.c:5018
Code: 63 9c 24 80 00 00 00 48 89 d8 48 c1 e8 06 48 8d 3c c5 20 82 49 90 be 08 00 00 00 e8 11 4f 77 00 48 bf 00 00 00 00 00 fc ff df <48> 0f a3 1d df 36 df 0e 0f 83 40 08 00 00 49 8d 9d d0 0a 00 00 48
RSP: 0018:ffffc90000af79a0 EFLAGS: 00000056
RAX: 0000000000000001 RBX: 000000000000002b RCX: ffffffff816a4b2f
RDX: 0000000000000000 RSI: 0000000000000008 RDI: dffffc0000000000
RBP: ffff8880166dc6b0 R08: dffffc0000000000 R09: fffffbfff2093045
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff8880166dc658
R13: ffff8880166dbb80 R14: ffff8880166dc6d0 R15: 1ffff11002cdb8da
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c00a908948 CR3: 000000000ce8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661
rcu_lock_acquire include/linux/rcupdate.h:306 [inline]
rcu_read_lock include/linux/rcupdate.h:747 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
batadv_nc_worker+0xe8/0x610 net/batman-adv/network-coding.c:719
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>


---
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If the bug is already fixed, let syzbot know by replying with:
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(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
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If you want to undo deduplication, reply with:
#syz undup

syzbot

unread,
Jan 17, 2024, 4:52:13 AMJan 17
to syzkaller...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
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