[syzbot] [mm?] INFO: task hung in migrate_pages_batch (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5472d60c129f Merge tag 'trace-v6.18-2' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=129bba7c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8dbddd36d9f68a5e
dashboard link: https://syzkaller.appspot.com/bug?extid=f523acb98cd782b4872e
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, 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/3726636cb074/disk-5472d60c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c893bfa7d66d/vmlinux-5472d60c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b93fdd7cec90/bzImage-5472d60c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f523ac...@syzkaller.appspotmail.com

INFO: task syz.4.865:9483 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.865 state:D stack:25592 pid:9483 tgid:9481 ppid:5824 task_flags:0x400040 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1190/0x5de0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:7026
io_schedule+0xbf/0x130 kernel/sched/core.c:7871
folio_wait_bit_common+0x3d5/0x9e0 mm/filemap.c:1330
folio_lock include/linux/pagemap.h:1141 [inline]
migrate_folio_unmap mm/migrate.c:1241 [inline]
migrate_pages_batch+0x1487/0x3bb0 mm/migrate.c:1882
migrate_pages_sync+0x4c5/0x8a0 mm/migrate.c:2026
migrate_pages+0x1b5f/0x23a0 mm/migrate.c:2108
compact_zone+0x2018/0x4750 mm/compaction.c:2647
compact_node+0x1a3/0x2c0 mm/compaction.c:2916
compact_nodes mm/compaction.c:2938 [inline]
sysctl_compaction_handler mm/compaction.c:2989 [inline]
sysctl_compaction_handler+0x141/0x210 mm/compaction.c:2976
proc_sys_call_handler+0x442/0x570 fs/proc/proc_sysctl.c:600
iter_file_splice_write+0xa24/0x12e0 fs/splice.c:738
do_splice_from fs/splice.c:938 [inline]
direct_splice_actor+0x18f/0x6c0 fs/splice.c:1161
splice_direct_to_actor+0x342/0xa30 fs/splice.c:1105
do_splice_direct_actor fs/splice.c:1204 [inline]
do_splice_direct+0x174/0x240 fs/splice.c:1230
do_sendfile+0xb06/0xe50 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1425 [inline]
__se_sys_sendfile64 fs/read_write.c:1417 [inline]
__x64_sys_sendfile64+0x154/0x220 fs/read_write.c:1417
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f298278eec9
RSP: 002b:00007f2983563038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f29829e6090 RCX: 00007f298278eec9
RDX: 00002000000000c0 RSI: 0000000000000006 RDI: 0000000000000007
RBP: 00007f2982811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f29829e6128 R14: 00007f29829e6090 R15: 00007ffdc1780a28
</TASK>

Showing all locks held in the system:
3 locks held by kworker/0:1/10:
#0: ffff88813ff51948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc900000f7d00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
#2: ffff88807d510240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1b6/0x6da0 drivers/net/netdevsim/fib.c:1490
1 lock held by khungtaskd/31:
#0: ffffffff8e3c44a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e3c44a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8e3c44a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
6 locks held by kworker/1:2/3733:
#0: ffff888144ec0d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc9000d22fd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
#2: ffff8881447a3198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
#2: ffff8881447a3198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x4fe0 drivers/usb/core/hub.c:5898
#3: ffff88801b7bb198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
#3: ffff88801b7bb198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1006
#4: ffff888053dad160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
#4: ffff888053dad160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1006
#5: ffff888075830068 (&state->mutex){+.+.}-{4:4}, at: az6007_write drivers/media/usb/dvb-usb-v2/az6007.c:178 [inline]
#5: ffff888075830068 (&state->mutex){+.+.}-{4:4}, at: az6007_power_ctrl+0x2f0/0x800 drivers/media/usb/dvb-usb-v2/az6007.c:703
1 lock held by acpid/5169:
#0: ffffffff8e3cfa38 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:343
2 locks held by getty/5577:
#0: ffff88814d0060a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
1 lock held by syz-executor/5797:
4 locks held by udevd/5809:
#0: ffff8880496228b8 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x12d0 fs/seq_file.c:182
#1: ffff888034640088 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172
#2: ffff88804ae63008 (kn->active#24){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
#2: ffff88804ae63008 (kn->active#24){++++}-{0:0}, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:173
#3: ffff88801b7bb198 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:919 [inline]
#3: ffff88801b7bb198 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
1 lock held by syz-executor/5814:
#0: ffffffff8e3cfa38 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:343
4 locks held by kworker/0:4/5869:
#0: ffff888144ec0d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc900043a7d00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
#2: ffff888029493198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
#2: ffff888029493198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x4fe0 drivers/usb/core/hub.c:5898
#3: ffff888031acf198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
#3: ffff888031acf198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1006
1 lock held by udevd/8053:
#0: ffff888142f51358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:945
1 lock held by syz.4.865/9483:
#0: ffff88803451c420 (sb_writers#3){.+.+}-{0:0}, at: splice_direct_to_actor+0x342/0xa30 fs/splice.c:1105
1 lock held by syz.3.1367/11417:
#0: ffffffff8e3cf900 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6e0 kernel/rcu/tree.c:3820

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf3f/0x1170 kernel/hung_task.c:495
kthread+0x3c2/0x780 kernel/kthread.c:463
ret_from_fork+0x672/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: d7 75 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 e6 24 00 fb f4 <e9> 0c 0a 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e007df8 EFLAGS: 000002c2
RAX: 000000000252e2c3 RBX: 0000000000000000 RCX: ffffffff8b6532d9
RDX: 0000000000000000 RSI: ffffffff8db02c74 RDI: ffffffff8bf1d240
RBP: fffffbfff1c12f40 R08: 0000000000000001 R09: ffffed1017086655
R10: ffff8880b84332ab R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8e097a00 R14: ffffffff908329d0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8881249dd000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2fc0eff8 CR3: 000000007dd80000 CR4: 00000000003526f0
Call Trace:
<TASK>
arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
default_idle+0x13/0x20 arch/x86/kernel/process.c:767
default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:190 [inline]
do_idle+0x38d/0x500 kernel/sched/idle.c:330
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
rest_init+0x16b/0x2b0 init/main.c:757
start_kernel+0x3f3/0x4e0 init/main.c:1111
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291
common_startup_64+0x13e/0x148
</TASK>


---
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