rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4426/1:b..l (detected by 0, t=10502 jiffies, g=11653, q=142 ncpus=2) task:syz.1.19 state:R running task stack:25248 pid:4426 ppid:4254 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873 irqentry_exit+0x63/0x70 kernel/entry/common.c:439 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:rcu_is_watching+0x63/0xa0 kernel/rcu/tree.c:722 Code: 89 f7 e8 60 48 67 00 48 c7 c3 a8 57 03 00 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 2f 8b 03 65 ff 0d 55 68 97 7e <74> 0c 83 e0 04 c1 e8 02 5b 41 5e 41 5f c3 e8 b2 79 95 ff eb ed 48 RSP: 0018:ffffc9000532f4f0 EFLAGS: 00000286 RAX: 0000000000072f44 RBX: ffff8880b8e357a8 RCX: da668651909d9f00 RDX: ffff888027591dc0 RSI: ffffffff8abf1340 RDI: ffffffff8abf1300 RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff2117049 R10: fffffbfff2117049 R11: 1ffffffff2117048 R12: 0000000000000cc0 R13: dffffc0000000000 R14: ffffffff8c3d0970 R15: dffffc0000000000 rcu_read_lock include/linux/rcupdate.h:792 [inline] blk_cgroup_congested+0x54/0x220 block/blk-cgroup.c:2012 __cgroup_throttle_swaprate+0x6d/0x1a0 mm/swapfile.c:3671 cgroup_throttle_swaprate include/linux/swap.h:662 [inline] folio_throttle_swaprate include/linux/swap.h:671 [inline] shmem_add_to_page_cache+0x9c1/0x1c00 mm/shmem.c:717 shmem_get_folio_gfp+0x158b/0x3400 mm/shmem.c:1971 shmem_fault+0x1be/0x7b0 mm/shmem.c:2156 __do_fault+0x13b/0x4e0 mm/memory.c:4280 do_read_fault mm/memory.c:4631 [inline] do_fault mm/memory.c:4760 [inline] handle_pte_fault mm/memory.c:5031 [inline] __handle_mm_fault mm/memory.c:5173 [inline] handle_mm_fault+0x28ca/0x3e70 mm/memory.c:5294 faultin_page mm/gup.c:1026 [inline] __get_user_pages+0x3ff/0xeb0 mm/gup.c:1250 populate_vma_page_range+0x214/0x2b0 mm/gup.c:1607 __mm_populate+0x248/0x370 mm/gup.c:1721 mm_populate include/linux/mm.h:2823 [inline] vm_mmap_pgoff+0x203/0x2b0 mm/util.c:525 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7ff384b8e929 RSP: 002b:00007ff3849de038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007ff384db6160 RCX: 00007ff384b8e929 RDX: b635773f06ebbeef RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007ff384c10b39 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff384db6160 R15: 00007ffeb4764558 rcu: rcu_preempt kthread starved for 10534 jiffies! g11653 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:26496 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873 irqentry_exit+0x63/0x70 kernel/entry/common.c:439 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696 RIP: 0010:timer_delete_sync+0x181/0x2a0 kernel/time/timer.c:1456 Code: d5 75 10 00 4d 89 ef 48 85 db 49 bd 00 00 00 00 00 fc ff df 75 07 e8 be 75 10 00 eb 06 e8 b7 75 10 00 fb 65 8b 1d 87 0e 92 7e <89> de 81 e6 00 00 0f 00 31 ff e8 00 79 10 00 81 e3 00 00 0f 00 74 RSP: 0018:ffffc90000157b00 EFLAGS: 00000293 RAX: ffffffff817060b9 RBX: 0000000080000000 RCX: ffff88813fe95940 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000157bb0 R08: dffffc0000000000 R09: fffffbfff1bfd0b6 R10: fffffbfff1bfd0b6 R11: 1ffffffff1bfd0b5 R12: 1ffff9200002af60 R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc90000157be0 del_timer_sync include/linux/timer.h:198 [inline] schedule_timeout+0x164/0x280 kernel/time/timer.c:1966 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.141-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:736 Code: 48 89 df e8 47 d4 b8 f7 e9 4c ff ff ff e8 bd 15 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 17 24 4d 00 fb f4 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48 RSP: 0018:ffffffff8c607d88 EFLAGS: 000002c6 RAX: c557afacb3db2600 RBX: ffffffff8a197f77 RCX: c557afacb3db2600 RDX: 0000000000000001 RSI: ffffffff8a6bffe0 RDI: ffffffff8abf1360 RBP: ffffffff8c607ec0 R08: dffffc0000000000 R09: ffffed10171c6af6 R10: ffffed10171c6af6 R11: 1ffff110171c6af5 R12: 0000000000000000 R13: dffffc0000000000 R14: ffffffff8c6bc680 R15: 1ffffffff1bfd0f6 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c3985cb CR3: 000000007caa5000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: default_idle_call+0x84/0xc0 kernel/sched/idle.c:109 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x1fc/0x570 kernel/sched/idle.c:303 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401 rest_init+0x2dc/0x300 init/main.c:733 arch_call_rest_init+0xa/0xa init/main.c:893 start_kernel+0x490/0x539 init/main.c:1140 secondary_startup_64_no_verify+0xcf/0xdb