rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P2133/1:b..l
rcu: (detected by 1, t=10502 jiffies, g=18689, q=505 ncpus=2)
task:kworker/u8:5 state:R running task stack:20344 pid:2133 tgid:2133 ppid:2 task_flags:0x24248060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0x1539/0x5080 kernel/sched/core.c:6907
preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7234
irqentry_exit+0x599/0x620 kernel/entry/common.c:239
asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:222 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:233 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:649 [inline]
RIP: 0010:cpu_online include/linux/cpumask.h:1231 [inline]
RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline]
RIP: 0010:lock_acquire+0x50/0x330 kernel/locking/lockdep.c:5831
Code: ac 24 98 00 00 00 65 48 8b 05 fc 7e 9c 11 48 89 44 24 58 0f 1f 44 00 00 65 8b 05 ff 7e 9c 11 83 f8 08 0f 83 83 01 00 00 89 c0 <48> 0f a3 05 68 99 91 0e 73 0d e8 21 1f 09 00 84 c0 0f 84 ca 01 00
RSP: 0018:ffffc900051f6700 EFLAGS: 00000297
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e960160
RBP: ffffffff8236cd60 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff2065f57 R12: 0000000000000002
R13: ffffffff8e960160 R14: 0000000000000000 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
rcu_read_lock include/linux/rcupdate.h:850 [inline]
lruvec_stat_mod_folio+0x8c/0x4b0 mm/memcontrol.c:797
__folio_start_writeback+0x752/0x9b0 mm/page-writeback.c:3017
ext4_bio_write_folio+0xebb/0x1fe0 fs/ext4/page-io.c:584
mpage_process_page_bufs+0x6d5/0x8e0 fs/ext4/inode.c:2191
mpage_prepare_extent_to_map+0xe1b/0x16f0 fs/ext4/inode.c:2730
ext4_do_writepages+0xbac/0x4600 fs/ext4/inode.c:2871
ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3019
do_writepages+0x32e/0x550 mm/page-writeback.c:2554
__writeback_single_inode+0x133/0x1060 fs/fs-writeback.c:1750
writeback_sb_inodes+0x92e/0x1940 fs/fs-writeback.c:2041
__writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2118
wb_writeback+0x459/0xad0 fs/fs-writeback.c:2229
wb_check_old_data_flush fs/fs-writeback.c:2333 [inline]
wb_do_writeback fs/fs-writeback.c:2386 [inline]
wb_workfn+0xaee/0xef0 fs/fs-writeback.c:2414
process_one_work+0x949/0x15a0 kernel/workqueue.c:3279
process_scheduled_works kernel/workqueue.c:3362 [inline]
worker_thread+0xb46/0x1140 kernel/workqueue.c:3443
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: rcu_preempt kthread starved for 10445 jiffies! g18689 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:27624 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0x1539/0x5080 kernel/sched/core.c:6907
__schedule_loop kernel/sched/core.c:6989 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7004
schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6653 Comm: vhost-6652 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:pgd_offset_pgd include/linux/pgtable.h:-1 [inline]
RIP: 0010:gup_fast_pgd_range mm/gup.c:3098 [inline]
RIP: 0010:gup_fast mm/gup.c:3157 [inline]
RIP: 0010:gup_fast_fallback+0x46c/0x22e0 mm/gup.c:3202
Code: 08 84 c0 0f 85 c1 1d 00 00 8b 1d 7b da 19 0c bf 40 00 00 00 89 de e8 d3 c9 b3 ff 48 83 fb 3f 0f 87 cb 1d 00 00 e8 84 c5 b3 ff <48> 8b 94 24 a8 00 00 00 48 89 d0 89 d9 48 d3 e8 25 ff 01 00 00 4d
RSP: 0018:ffffc90003e5f7c0 EFLAGS: 00000093
RAX: ffffffff8211745c RBX: 0000000000000027 RCX: ffff888029b78000
RDX: 0000000000000000 RSI: 0000000000000027 RDI: 0000000000000040
RBP: ffffc90003e5f9b0 R08: ffffffff9032fab7 R09: 1ffffffff2065f56
R10: dffffc0000000000 R11: fffffbfff2065f57 R12: 0000000000080001
R13: ffffc90003e5fa20 R14: ffff888077308000 R15: ffffffff821171fd
FS: 00007f04451ac6c0(0000) GS:ffff888125042000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 0000000077308000 CR4: 00000000003526f0
Call Trace:
set_bit_to_user drivers/vhost/vhost.c:2425 [inline]
log_write+0xc2/0x3c0 drivers/vhost/vhost.c:2451
vhost_update_used_flags+0x1ed/0x2b0 drivers/vhost/vhost.c:2582
vhost_disable_notify+0xad/0x1d0 drivers/vhost/vhost.c:3263
vhost_vsock_handle_tx_kick+0x163/0x10a0 drivers/vhost/vsock.c:513
vhost_run_work_list+0x14d/0x1e0 drivers/vhost/vhost.c:454
vhost_task_fn+0x2ef/0x4a0 kernel/vhost_task.c:49
ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245