rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P9964/1:b..l P11004/2:b..l rcu: (detected by 0, t=10502 jiffies, g=37933, q=328 ncpus=2) task:syz.3.1322 state:R running task stack:23864 pid:11004 tgid:11003 ppid:5838 task_flags:0x2040044c flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6790 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7113 irqentry_exit+0x6f/0x90 kernel/entry/common.c:307 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_release+0x2b5/0x3e0 kernel/locking/lockdep.c:5896 Code: 51 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 75 56 f7 c3 00 02 00 00 74 01 fb 65 48 8b 05 3b af fe 10 <48> 3b 44 24 28 0f 85 8b 00 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e RSP: 0018:ffffc9000462e750 EFLAGS: 00000206 RAX: c0abeb809f03db00 RBX: 0000000000000202 RCX: c0abeb809f03db00 RDX: 0000000000000001 RSI: ffffffff8db707c4 RDI: ffffffff8be1c200 RBP: ffff888024c74718 R08: ffffc9000462ef10 R09: 0000000000000000 R10: ffffc9000462e8d8 R11: fffff520008c5d1d R12: 0000000000000001 R13: 0000000000000001 R14: ffffffff8e13ee60 R15: ffff888024c73c00 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0x19a9/0x2390 arch/x86/kernel/unwind_orc.c:680 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4359 kmalloc_noprof include/linux/slab.h:905 [inline] slab_free_hook mm/slub.c:2333 [inline] slab_free mm/slub.c:4643 [inline] kmem_cache_free+0x166/0x400 mm/slub.c:4745 blk_update_request+0x5eb/0xe70 block/blk-mq.c:987 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1149 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+0xbfe/0xe30 drivers/block/null_blk/main.c:1693 null_queue_rqs+0x123/0x270 drivers/block/null_blk/main.c:1707 __blk_mq_flush_list block/blk-mq.c:2826 [inline] blk_mq_dispatch_queue_requests+0x414/0x800 block/blk-mq.c:2871 blk_mq_flush_plug_list+0x432/0x550 block/blk-mq.c:2959 blk_add_rq_to_plug+0x175/0x450 block/blk-mq.c:1388 blk_mq_submit_bio+0xbd3/0x22d0 block/blk-mq.c:3208 __submit_bio+0x207/0x5a0 block/blk-core.c:635 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x4ab/0xb50 block/blk-core.c:751 __block_write_full_folio+0x810/0xe10 fs/buffer.c:1939 blkdev_writepages+0xd1/0x170 block/fops.c:483 do_writepages+0x32b/0x550 mm/page-writeback.c:2636 filemap_fdatawrite_wbc mm/filemap.c:386 [inline] __filemap_fdatawrite_range mm/filemap.c:419 [inline] filemap_write_and_wait_range+0x217/0x310 mm/filemap.c:691 filemap_write_and_wait include/linux/pagemap.h:68 [inline] sync_blockdev block/bdev.c:260 [inline] bdev_release+0x192/0x650 block/bdev.c:1126 blkdev_release+0x15/0x20 block/fops.c:684 __fput+0x44c/0xa70 fs/file_table.c:465 task_work_run+0x1d4/0x260 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x6b5/0x22e0 kernel/exit.c:964 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105 get_signal+0x125e/0x1310 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3fa078e929 RSP: 002b:00007f3fa1511038 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 RAX: fffffffffffffe00 RBX: 00007f3fa09b5fa0 RCX: 00007f3fa078e929 RDX: 000000000000006f RSI: 0000000000000084 RDI: 0000000000000004 RBP: 00007f3fa0810b39 R08: 0000200000000180 R09: 0000000000000000 R10: 0000200000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f3fa09b5fa0 R15: 00007ffc7d9fd928 task:kworker/u8:16 state:R running task stack:22888 pid:9964 tgid:9964 ppid:2 task_flags:0x4208060 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6790 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7113 irqentry_exit+0x6f/0x90 kernel/entry/common.c:307 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707 RIP: 0010:lock_acquire+0x0/0x360 kernel/locking/lockdep.c:5831 Code: 05 55 c3 fe 10 a9 00 ff ff 00 0f 95 c0 c3 cc cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 55 41 57 41 56 41 55 41 54 53 48 83 ec 60 4d 89 ce 45 RSP: 0018:ffffc900033c7a10 EFLAGS: 00000246 RAX: 0000000000000001 RBX: ffff88802d8e0380 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e13ee60 RBP: ffff88807722c938 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: fffffbfff1f4177f R12: dffffc0000000000 R13: ffffffff8b35bfc2 R14: ffff888030634d80 R15: 0000000000000127 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline] batadv_nc_worker+0xef/0x610 net/batman-adv/network-coding.c:719 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread timer wakeup didn't happen for 10582 jiffies! g37933 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=28266 rcu: rcu_preempt kthread starved for 10583 jiffies! g37933 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 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:I stack:27320 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6790 __schedule_loop kernel/sched/core.c:6868 [inline] schedule+0x165/0x360 kernel/sched/core.c:6883 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 11030 Comm: syz.2.1329 Not tainted 6.16.0-rc5-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:check_preemption_disabled+0x40/0x120 lib/smp_processor_id.c:55 Code: 08 65 8b 05 26 de 34 07 65 8b 0d 1b de 34 07 f7 c1 ff ff ff 7f 74 23 65 48 8b 0d fb dd 34 07 48 3b 4c 24 08 0f 85 cc 00 00 00 <48> 83 c4 10 5b 41 5e 41 5f 5d c3 cc cc cc cc cc 48 c7 04 24 00 00 RSP: 0018:ffffc900040b6f48 EFLAGS: 00000246 RAX: 0000000000000001 RBX: 0000000000000000 RCX: adf2ecc79ea82100 RDX: ffff8880256b0000 RSI: ffffffff8be1c1e0 RDI: ffffffff8be1c1a0 RBP: 0000000000000001 R08: ffff8880256b0000 R09: 0000000000000002 R10: 00000000ffffffff R11: 0000000000000002 R12: 00000000fffffff1 R13: dffffc0000000000 R14: ffff888035f1a000 R15: ffff88807b356000 FS: 00007ff522bb46c0(0000) GS:ffff888125d51000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c3b7c21 CR3: 0000000058bb4000 CR4: 00000000003526f0 Call Trace: rcu_lockdep_current_cpu_online+0x37/0x120 kernel/rcu/tree.c:3998 rcu_read_lock_held_common kernel/rcu/update.c:113 [inline] rcu_read_lock_held+0x1e/0x50 kernel/rcu/update.c:349 qdisc_lookup_rcu+0x68/0x6d0 net/sched/sch_api.c:327 qdisc_tree_reduce_backlog+0x1b2/0x480 net/sched/sch_api.c:800 fq_change+0x1519/0x1f50 net/sched/sch_fq.c:1147 fq_init+0x699/0x960 net/sched/sch_fq.c:1201 qdisc_create+0x7ac/0xea0 net/sched/sch_api.c:1324 __tc_modify_qdisc net/sched/sch_api.c:1749 [inline] tc_modify_qdisc+0x1426/0x2010 net/sched/sch_api.c:1813 rtnetlink_rcv_msg+0x779/0xb70 net/core/rtnetlink.c:6953 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:727 ____sys_sendmsg+0x505/0x830 net/socket.c:2566 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff524d8e929 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff522bb4038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007ff524fb6160 RCX: 00007ff524d8e929 RDX: 0000000000000000 RSI: 0000200000001200 RDI: 000000000000000d RBP: 00007ff524e10b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff524fb6160 R15: 00007ffc680bf0b8 hrtimer: interrupt took 1630070863 ns