rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6991/2:b..l
rcu: (detected by 0, t=10502 jiffies, g=14769, q=1348 ncpus=2)
task:syz.2.323 state:R running task stack:25304 pid:6991 tgid:6989 ppid:5825 task_flags:0x20400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1139/0x6150 kernel/sched/core.c:6863
preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190
irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:unwind_next_frame+0xc46/0x20b0 arch/x86/kernel/unwind_orc.c:656
Code: c0 49 c7 45 58 00 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 0f b6 34 10 49 8d 40 01 48 89 c7 48 c1 ef 03 0f b6 14 17 <4c> 89 c7 83 e7 07 40 38 fe 40 0f 9e c7 40 84 f6 40 0f 95 c6 40 84
RSP: 0018:ffffc9000443eea8 EFLAGS: 00000a07
RAX: ffffffff9159a67f RBX: 0000000000000001 RCX: ffffffff9159a67a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 1ffffffff22b34cf
RBP: ffffc9000443ef60 R08: ffffffff9159a67e R09: 000000000ac0d5af
R10: 0000000000000002 R11: 0000000000038868 R12: ffffc9000443ef68
R13: ffffc9000443ef18 R14: ffffc9000443f870 R15: ffffc9000443ef4c
arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
__call_rcu_common.constprop.0+0xa5/0xa10 kernel/rcu/tree.c:3119
slab_free_hook mm/slub.c:2504 [inline]
slab_free mm/slub.c:6670 [inline]
kmem_cache_free+0x171/0x770 mm/slub.c:6781
mempool_free+0xde/0x130 mm/mempool.c:712
bio_put_percpu_cache block/bio.c:808 [inline]
bio_put+0x355/0x5b0 block/bio.c:827
bio_endio+0x751/0x8a0 block/bio.c:1675
blk_update_request+0x914/0x15c0 block/blk-mq.c:1007
blk_mq_end_request+0x59/0x430 block/blk-mq.c:1169
blk_mq_complete_request block/blk-mq.c:1347 [inline]
blk_mq_complete_request+0x8b/0xb0 block/blk-mq.c:1344
nullb_complete_cmd drivers/block/null_blk/main.c:1402 [inline]
null_handle_cmd drivers/block/null_blk/main.c:1454 [inline]
null_queue_rq+0xb69/0xfd0 drivers/block/null_blk/main.c:1693
null_queue_rqs+0xe9/0x2f0 drivers/block/null_blk/main.c:1707
__blk_mq_flush_list block/blk-mq.c:2848 [inline]
__blk_mq_flush_list+0x9a/0xc0 block/blk-mq.c:2844
blk_mq_dispatch_queue_requests+0x184/0x7b0 block/blk-mq.c:2893
blk_mq_flush_plug_list+0x1f2/0x600 block/blk-mq.c:2981
__blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
blk_finish_plug+0x53/0xa0 block/blk-core.c:1249
blkdev_writepages+0xe9/0x140 block/fops.c:488
do_writepages+0x27a/0x600 mm/page-writeback.c:2598
filemap_writeback+0x225/0x2d0 mm/filemap.c:387
filemap_fdatawrite_range mm/filemap.c:412 [inline]
filemap_write_and_wait_range.part.0+0x88/0x110 mm/filemap.c:684
filemap_write_and_wait_range mm/filemap.c:680 [inline]
filemap_invalidate_pages mm/filemap.c:2904 [inline]
kiocb_invalidate_pages+0xde/0x180 mm/filemap.c:2923
blkdev_direct_write block/fops.c:716 [inline]
blkdev_write_iter+0x48f/0xe00 block/fops.c:791
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x7d3/0x11d0 fs/read_write.c:686
ksys_write+0x12a/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f652e18f749
RSP: 002b:00007f652c3f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f652e3e6090 RCX: 00007f652e18f749
RDX: 00000000ffffffdb RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f652e213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f652e3e6128 R14: 00007f652e3e6090 R15: 00007ffc0907a288
rcu: rcu_preempt kthread starved for 10561 jiffies! g14769 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:28440 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1139/0x6150 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:6960
schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: Stack dump where RCU GP kthread last ran:
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 10/25/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: b6 5f 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 13 39 12 00 fb f4 cc 35 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e007df8 EFLAGS: 000002c6
RAX: 00000000007732d9 RBX: 0000000000000000 RCX: ffffffff8b7826d9
RDX: 0000000000000000 RSI: ffffffff8dacdf23 RDI: ffffffff8bf2b400
RBP: fffffbfff1c12f68 R08: 0000000000000001 R09: ffffed101708673d
R10: ffff8880b84339eb R11: ffffffff8e098670 R12: 0000000000000000
R13: ffffffff8e097b40 R14: ffffffff9088b4d0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8881248f5000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000002e000 CR3: 000000005d59e000 CR4: 00000000003526f0
Call Trace:
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:191 [inline]
do_idle+0x38d/0x510 kernel/sched/idle.c:332
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430
rest_init+0x16b/0x2b0 init/main.c:757
start_kernel+0x3ef/0x4d0 init/main.c:1206
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