rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5617/1:b..l P5564/1:b..l (detected by 1, t=10503 jiffies, g=20317, q=191 ncpus=2) task:syz.1.296 state:R running task stack:23792 pid:5564 ppid:4272 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874 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:check_kcov_mode kernel/kcov.c:182 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x13/0x60 kernel/kcov.c:216 Code: 48 8b 3d f0 52 9d 0c 48 89 de 5b e9 67 21 50 00 00 00 cc cc 00 00 cc 48 8b 04 24 65 48 8b 0d c4 fc 7f 7e 65 8b 15 c5 fc 7f 7e <81> e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 RSP: 0018:ffffc90005016c98 EFLAGS: 00000246 RAX: ffffffff8156e9d0 RBX: ffff88807e21bb80 RCX: ffff88807e21bb80 RDX: 0000000080000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: dffffc0000000000 R09: 1ffffffff215e648 R10: dffffc0000000000 R11: fffffbfff215e649 R12: 0000000000000cc0 R13: 0000000000000001 R14: ffff88807e21bbac R15: dffffc0000000000 kthread_blkcg+0x50/0xd0 kernel/kthread.c:1528 blkcg_css+0x10/0x1c0 block/blk-cgroup.c:74 blk_cgroup_congested+0xba/0x220 block/blk-cgroup.c:2013 __cgroup_throttle_swaprate+0x6d/0x1a0 mm/swapfile.c:3671 cgroup_throttle_swaprate include/linux/swap.h:672 [inline] folio_throttle_swaprate include/linux/swap.h:681 [inline] shmem_add_to_page_cache+0x9ec/0x1c50 mm/shmem.c:717 shmem_get_folio_gfp+0x158e/0x3400 mm/shmem.c:1971 shmem_get_folio mm/shmem.c:2072 [inline] shmem_write_begin+0xee/0x3f0 mm/shmem.c:2556 generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862 __generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960 generic_file_write_iter+0xab/0x2e0 mm/filemap.c:3989 __kernel_write_iter+0x285/0x650 fs/read_write.c:517 dump_emit_page fs/coredump.c:950 [inline] dump_user_range+0x412/0x850 fs/coredump.c:977 elf_core_dump+0x30a6/0x35d0 fs/binfmt_elf.c:2354 do_coredump+0x165b/0x22f0 fs/coredump.c:824 get_signal+0x10aa/0x1350 kernel/signal.c:2857 arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1490 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0033:0x7f563939acc1 RSP: 002b:fffffffffffffe70 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007f5639616090 RCX: 00007f563939acb9 RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000 RBP: 00007f5639408bf7 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 00007f5639616128 R14: 00007f5639616090 R15: 00007ffe4cbcc3b8 task:sed state:R running task stack:24336 pid:5617 ppid:5616 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874 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:mas_validate_limits lib/maple_tree.c:7141 [inline] RIP: 0010:mt_validate+0x1c82/0x4cb0 lib/maple_tree.c:7244 Code: f4 ac ec 0c 4c 8b 74 24 20 4c 89 f7 4c 89 fe e8 54 a5 68 f7 4d 39 fe 0f 87 8b 00 00 00 e8 66 a3 68 f7 4c 8b b4 24 20 01 00 00 <4c> 89 ff 4c 89 f6 e8 33 a5 68 f7 4d 39 f7 0f 82 1f 01 00 00 e8 45 RSP: 0018:ffffc9000526f1c0 EFLAGS: 00000293 RAX: ffffffff8a19cf0a RBX: 0000000000000004 RCX: ffff88802be50000 RDX: 0000000000000000 RSI: 00007f529ad4bfff RDI: 00007f529ad4afff RBP: ffffc9000526f370 R08: ffff88802be50000 R09: 0000000000000003 R10: 0000000000000003 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff88805a59ac80 R14: 00007f529ac97000 R15: 00007f529ad4bfff validate_mm_mt+0xe2/0x440 mm/mmap.c:295 validate_mm+0xe1/0x2e0 mm/mmap.c:332 __vma_adjust+0x1855/0x1cd0 mm/mmap.c:879 vma_adjust include/linux/mm.h:2810 [inline] __split_vma+0x3a7/0x500 mm/mmap.c:-1 do_mas_align_munmap+0x7b9/0x12b0 mm/mmap.c:2501 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2650 __mmap_region mm/mmap.c:2698 [inline] mmap_region+0x6e0/0x1ca0 mm/mmap.c:2916 do_mmap+0x964/0xfd0 mm/mmap.c:1436 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:520 ksys_mmap_pgoff+0x516/0x6f0 mm/mmap.c:1482 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f529ad6d242 RSP: 002b:00007ffc16efd5f8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f529aa91000 RCX: 00007f529ad6d242 RDX: 0000000000000005 RSI: 0000000000002000 RDI: 00007f529aa91000 RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000002000 R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffc16efd648 R13: 00007f529ad4a050 R14: 00007ffc16efda30 R15: 00000fff82ddfac2 rcu: rcu_preempt kthread starved for 10588 jiffies! g20317 f0x0 RCU_GP_WAIT_FQS(5) ->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:28016 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 schedule+0xb9/0x180 kernel/sched/core.c:6638 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x99/0x3b0 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: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742 Code: 48 89 df e8 a7 10 9d f7 e9 44 ff ff ff e8 7d 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 87 5d 50 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:ffffc90000177de8 EFLAGS: 000002c6 RAX: ebffd9ef57680700 RBX: ffffffff8a3651a7 RCX: ebffd9ef57680700 RDX: 0000000000000001 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0c20 RBP: ffffc90000177f20 R08: ffff8880b8f3580b R09: 1ffff110171e6b01 R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 1ffff9200002efc8 R13: dffffc0000000000 R14: ffff888017731dc0 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8d419e8400 CR3: 000000006817f000 CR4: 00000000003506e0 Call Trace: default_idle_call+0x84/0xc0 kernel/sched/idle.c:109 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x20d/0x5a0 kernel/sched/idle.c:303 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401 start_secondary+0xe4/0xf0 arch/x86/kernel/smpboot.c:281 secondary_startup_64_no_verify+0xcf/0xdb