rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5987/1:b..l rcu: (detected by 0, t=10503 jiffies, g=7813, q=1269 ncpus=2) task:syz.0.19 state:R running task stack:26536 pid:5987 tgid:5980 ppid:5808 task_flags:0x40044c flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7194 irqentry_exit+0x17b/0x670 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x5e/0x330 kernel/locking/lockdep.c:5872 Code: 05 bb 32 01 12 83 f8 07 0f 87 a4 02 00 00 48 0f a3 05 46 2e d4 0e 0f 82 6f 02 00 00 8b 35 de 5e d4 0e 85 f6 0f 85 8a 00 00 00 <48> 8b 44 24 30 65 48 2b 05 5d 32 01 12 0f 85 b8 02 00 00 48 83 c4 RSP: 0018:ffffc9000517f4d8 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8dc1f504 RDI: ffffffff8bfa35a0 RBP: ffffffff8e5e32e0 R08: 0000000086db7919 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:867 [inline] class_rcu_constructor include/linux/rcupdate.h:1195 [inline] unwind_next_frame+0xd1/0x1ea0 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 save_stack+0x162/0x1e0 mm/page_owner.c:165 __reset_page_owner+0x84/0x190 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0x822/0x1130 mm/page_alloc.c:2973 __folio_put+0x3b4/0x540 mm/swap.c:112 folio_put_refs include/linux/mm.h:1636 [inline] gup_put_folio+0x1cb/0x270 mm/gup.c:114 unpin_all_folios drivers/dma-buf/udmabuf.c:203 [inline] deinit_udmabuf drivers/dma-buf/udmabuf.c:229 [inline] release_udmabuf+0x1c7/0x320 drivers/dma-buf/udmabuf.c:242 dma_buf_release+0x159/0x2d0 drivers/dma-buf/dma-buf.c:160 __dentry_kill+0x23e/0x600 fs/dcache.c:675 finish_dput+0x76/0x480 fs/dcache.c:879 dput.part.0+0x456/0x570 fs/dcache.c:928 dput+0x1f/0x30 fs/dcache.c:920 __fput+0x519/0xb40 fs/file_table.c:476 task_work_run+0x150/0x240 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x829/0x2a30 kernel/exit.c:971 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034 arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x86/0x4b0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4fe/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f57ec79aeb9 RSP: 002b:00007f57ed5e9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000003 RBX: 00007f57eca16090 RCX: 00007f57ec79aeb9 RDX: 0000200000000000 RSI: 0000000040187542 RDI: 0000000000000009 RBP: 00007f57ec808c1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f57eca16128 R14: 00007f57eca16090 R15: 00007ffdc947a1c8 rcu: rcu_preempt kthread starved for 1497 jiffies! g7813 f0x0 RCU_GP_DOING_FQS(6) ->state=0x0 ->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:R running task stack:28408 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7194 irqentry_exit+0x17b/0x670 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:force_qs_rnp+0x15/0xa80 kernel/rcu/tree.c:2727 Code: 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 41 57 41 56 41 55 41 54 55 53 48 83 ec 70 0f b6 05 90 0a 73 0c 05 89 0a 73 0c 00 48 89 7c 24 08 88 05 7d 0a 73 0c 8b 05 6b 5b RSP: 0018:ffffc90000157b88 EFLAGS: 00000286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006 RDX: 1ffffffff1c42250 RSI: ffffffff8dc454ef RDI: ffffffff81ec1790 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8e211280 R13: ffffc90000157c98 R14: 1ffff9200002af87 R15: 0000000000000000 rcu_gp_fqs kernel/rcu/tree.c:2039 [inline] rcu_gp_fqs_loop+0x6b6/0xb00 kernel/rcu/tree.c:2105 rcu_gp_kthread+0x21e/0x320 kernel/rcu/tree.c:2285 kthread+0x3b3/0x730 kernel/kthread.c:463 ret_from_fork+0x754/0xaf0 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: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: 66 78 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 83 bc 14 00 fb f4 fc 31 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffc90000197df0 EFLAGS: 00000246 RAX: 0000000001f09005 RBX: ffff88801e2aa4c0 RCX: ffffffff8b76c4b5 RDX: 0000000000000000 RSI: ffffffff8dc454ef RDI: ffffffff8bfa35a0 RBP: 0000000000000001 R08: 0000000000000001 R09: ffffed10170a673d R10: ffff8880b85339eb R11: 0000000000000000 R12: ffffed1003c55498 R13: 0000000000000001 R14: ffffffff90b74bd0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881246db000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000057000 CR3: 000000007c820000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x9/0x10 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+0x35b/0x4b0 kernel/sched/idle.c:332 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x148 net_ratelimit: 12951 callbacks suppressed bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:3a:bc:45:27:01:d9, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:3a:bc:45:27:01:d9, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:36:2f:d9:ba:c8:9a, vlan:0) net_ratelimit: 18929 callbacks suppressed bridge0: received packet on veth0_to_bridge with own address as source address (addr:3a:bc:45:27:01:d9, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:36:2f:d9:ba:c8:9a, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0) bridge0: received packet on veth0_to_bridge with own address as source address (addr:36:2f:d9:ba:c8:9a, vlan:0) bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)