From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f72.google.com (mail-oa1-f72.google.com [209.85.160.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1CCCA357732 for ; Mon, 12 Jan 2026 13:13:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.72 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768223584; cv=none; b=JuYSUkSmkj9BsIMelIgdZP1xCQLAAi/6LrlHqITKZe0lW7Qa4r//ObvNoEht/oBdlkkRoGR+o3a6cXP2wHAM5md3kVfWZ231EZeZzZNLXcVGsg9tG6N3C3RNL5IT7wPbQKrKfJpRUOF4Zn1n4m6xX5fhPytIdgZHoViOUvSilsg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768223584; c=relaxed/simple; bh=/a9LhYhXeQTwhB2K9OCc0IqjfFZ2/SH/NuluosdIWF4=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:22a7:b0:65d:7e5:d49d with SMTP id 006d021491bc7-65f5509e346mr9171331eaf.72.1768223582167; Mon, 12 Jan 2026 05:13:02 -0800 (PST) Date: Mon, 12 Jan 2026 05:13:02 -0800 In-Reply-To: <20260112120904.2172-1-hdanton@sina.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6964f35e.050a0220.eaf7.00a5.GAE@google.com> Subject: Re: [syzbot] [mm?] INFO: rcu detected stall in purge_vmap_node From: syzbot To: akpm@linux-foundation.org, hdanton@sina.com, kartikey406@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, urezki@gmail.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: INFO: rcu detected stall in x64_sys_call rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6717/1:b..l P5934/1:b..l rcu: (detected by 1, t=10502 jiffies, g=15885, q=682 ncpus=2) task:kworker/1:4 state:R running task stack:27080 pid:5934 tgid:5934 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: events cleanup_vm_area_work 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_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:unwind_next_frame+0x14e/0x20b0 arch/x86/kernel/unwind_orc.c:510 Code: c0 74 08 3c 01 0f 8e 20 0a 00 00 41 f6 86 88 00 00 00 03 0f 85 71 02 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8d 75 35 4c 89 f2 <48> c1 ea 03 0f b6 04 02 4c 89 f2 83 e2 07 38 d0 7f 08 84 c0 0f 85 RSP: 0018:ffffc900033477a8 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: 0000000000000001 RCX: 00000000c5fffc65 RDX: ffffc9000334784d RSI: ffffffff8bf2b380 RDI: ffffffff8dd7cf28 RBP: ffffc90003347860 R08: 0000000076218ff6 R09: 00000000676218ff R10: 0000000000000002 R11: ffff888025fb54b0 R12: ffffc90003347868 R13: ffffc90003347818 R14: ffffc9000334784d R15: ffff888025fb4980 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 save_stack+0x160/0x1f0 mm/page_owner.c:165 __reset_page_owner+0x84/0x1a0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0x7df/0x1170 mm/page_alloc.c:2943 vfree+0x1fd/0xb50 mm/vmalloc.c:3474 cleanup_vm_area_work+0x4c/0x100 mm/vmalloc.c:3771 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 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 task:cmp state:R running task stack:25800 pid:6717 tgid:6717 ppid:6660 task_flags:0x40000c flags:0x00080000 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:rcu_lock_acquire include/linux/rcupdate.h:331 [inline] RIP: 0010:rcu_read_lock include/linux/rcupdate.h:867 [inline] RIP: 0010:class_rcu_constructor include/linux/rcupdate.h:1195 [inline] RIP: 0010:unwind_next_frame+0xbe/0x20b0 arch/x86/kernel/unwind_orc.c:495 Code: ea 03 80 3c 02 00 0f 85 5d 18 00 00 49 8b 45 38 48 89 44 24 10 e8 c2 47 36 00 31 d2 45 31 c9 45 31 c0 48 8d 05 00 00 00 00 50 02 00 00 00 31 f6 48 c7 c7 a0 96 3c 8e e8 1f 45 2d 00 e8 da 80 RSP: 0018:ffffc900032e75b8 EFLAGS: 00000246 RAX: ffffffff816cb66d RBX: 0000000000000001 RCX: ffffc900032e7584 RDX: 0000000000000000 RSI: ffffffff817b2e92 RDI: ffff8880338ea944 RBP: ffffc900032e7678 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000007b2b R12: ffffffff81a96170 R13: ffffc900032e7630 R14: 0000000000000000 R15: ffff8880338ea4c0 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:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2540 [inline] slab_free mm/slub.c:6670 [inline] kmem_cache_free+0x2d8/0x770 mm/slub.c:6781 anon_vma_chain_free mm/rmap.c:146 [inline] unlink_anon_vmas+0x173/0x820 mm/rmap.c:420 free_pgtables+0x212/0xc10 mm/memory.c:414 exit_mmap+0x3f1/0xb60 mm/mmap.c:1288 __mmput+0x12a/0x410 kernel/fork.c:1173 mmput+0x62/0x70 kernel/fork.c:1196 exit_mm kernel/exit.c:581 [inline] do_exit+0x7d7/0x2bd0 kernel/exit.c:959 do_group_exit+0xd3/0x2a0 kernel/exit.c:1112 __do_sys_exit_group kernel/exit.c:1123 [inline] __se_sys_exit_group kernel/exit.c:1121 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1121 x64_sys_call+0x151c/0x1740 arch/x86/include/generated/asm/syscalls_64.h:232 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: 0033:0x7f3b0dc696c5 RSP: 002b:00007ffe72640248 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f3b0dd6afe8 RCX: 00007f3b0dc696c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000 RBP: 0000000000000001 R08: 00007ffe726401d8 R09: 0000000000000000 R10: 00007ffe72640070 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f3b0dd69680 R15: 00007f3b0dd6b000 rcu: rcu_preempt kthread starved for 10573 jiffies! g15885 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:27720 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: 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 10/25/2025 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: a6 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 19 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: 0000:ffffc90000197de8 EFLAGS: 000002c6 RAX: 00000000000e7bab RBX: 0000000000000001 RCX: ffffffff8b7846d9 RDX: 0000000000000000 RSI: ffffffff8daceab2 RDI: ffffffff8bf2b400 RBP: ffffed1003b56498 R08: 0000000000000001 R09: ffffed10170a673d R10: ffff8880b85339eb R11: ffff88801dab2ff0 R12: 0000000000000001 R13: ffff88801dab24c0 R14: ffffffff9088bdd0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881249f5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005555787857d0 CR3: 000000003ccf6000 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 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x148 Tested on: commit: 0f61b186 Linux 6.19-rc5 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=102239fc580000 kernel config: https://syzkaller.appspot.com/x/.config?x=1859476832863c41 dashboard link: https://syzkaller.appspot.com/bug?extid=d8d4c31d40f868eaea30 compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=167a399a580000