From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f198.google.com (mail-il1-f198.google.com [209.85.166.198]) (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 8FF261AAE17 for ; Thu, 28 Aug 2025 03:08:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756350487; cv=none; b=FIqWIWE2pO63B2Q2XyIndqvN9l5CLNQXnXG6xUWdz/Q3wrynP+vSiMumcxAxnyyVYFIgA16NOnN29ZDpzG5LpW2GyYlbGELX4eCnlQ3YsOiDaDpU0uXW5JwJ6/xqiHLegcmZSOnnvhbFfTxYLu66HUNYEh+KX/CZVO2yYOZQjGo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756350487; c=relaxed/simple; bh=OBbafKjywxsHzUmzz7M30RIkaRAUiga+jtQnihqR7OM=; 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:a05:6e02:1aa2:b0:3f1:f2:1a47 with SMTP id e9e14a558f8ab-3f100f21bb3mr32320155ab.31.1756350484705; Wed, 27 Aug 2025 20:08:04 -0700 (PDT) Date: Wed, 27 Aug 2025 20:08:04 -0700 In-Reply-To: X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <68afc814.050a0220.8762d.0005.GAE@google.com> Subject: Re: [syzbot] [mm?] INFO: rcu detected stall in sys_munmap (2) From: syzbot To: akpm@linux-foundation.org, jannh@google.com, liam.howlett@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, pfalcato@suse.de, syzkaller-bugs@googlegroups.com, vbabka@suse.cz 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 corrupted rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5218/1:b..l rcu: (detected by 0, t=10502 jiffies, g=10417, q=327 ncpus=2) task:udevd state:R running task stack:26640 pid:5218 tgid:5218 ppid:1 task_flags:0x400140 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288 irqentry_exit+0x36/0x90 kernel/entry/common.c:197 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707 RIP: 0010:lock_acquire+0x30/0x350 kernel/locking/lockdep.c:5828 Code: 4d 89 cf 41 56 41 89 f6 41 55 41 89 d5 41 54 45 89 c4 55 89 cd 53 48 89 fb 48 83 ec 38 65 48 8b 05 0d 79 3e 12 48 89 44 24 30 <31> c0 66 90 65 8b 05 29 79 3e 12 83 f8 07 0f 87 bc 02 00 00 89 c0 RSP: 0018:ffffc90003d0f530 EFLAGS: 00000286 RAX: 4b548df46ee33600 RBX: ffffffff8e5c11e0 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e5c11e0 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: ffffc90003d0f618 R11: 00000000000135a3 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xd1/0x20a0 arch/x86/kernel/unwind_orc.c:479 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:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2417 [inline] slab_free mm/slub.c:4680 [inline] kfree+0x2b4/0x4d0 mm/slub.c:4879 tomoyo_realpath_from_path+0x19f/0x6e0 security/tomoyo/realpath.c:286 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_perm+0x274/0x460 security/tomoyo/file.c:822 security_inode_getattr+0x116/0x290 security/security.c:2377 vfs_getattr fs/stat.c:259 [inline] vfs_statx_path fs/stat.c:299 [inline] vfs_statx+0x121/0x3f0 fs/stat.c:356 vfs_fstatat+0x7b/0xf0 fs/stat.c:375 __do_sys_newfstatat+0x97/0x120 fs/stat.c:542 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f47f6d11b0a RSP: 002b:00007ffd84c35818 EFLAGS: 00000246 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 0000559b20c5e418 RCX: 00007f47f6d11b0a RDX: 00007ffd84c35820 RSI: 0000559b20c4cef3 RDI: 00000000ffffff9c RBP: 0000559b5aa6d668 R08: 00063d641a57c867 R09: 00007f47f7457000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffd84c35820 R14: 0000000000000000 R15: 00063d641a57c867 rcu: rcu_preempt kthread starved for 966 jiffies! g10417 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:28936 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d7/0x6f0 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: 6556 Comm: syz.1.23 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:36 [inline] RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:139 [inline] RIP: 0010:wrmsrq arch/x86/include/asm/msr.h:199 [inline] RIP: 0010:native_apic_msr_write arch/x86/include/asm/apic.h:212 [inline] RIP: 0010:native_apic_msr_write+0x28/0x40 arch/x86/include/asm/apic.h:206 Code: 90 90 f3 0f 1e fa 8d 87 30 ff ff ff 83 e0 ef 74 20 89 f8 83 e0 ef 83 f8 20 74 16 c1 ef 04 31 d2 89 f0 8d 8f 00 08 00 00 0f 30 <66> 90 c3 cc cc cc cc c3 cc cc cc cc 89 f6 31 d2 89 cf e9 b1 4d ae RSP: 0018:ffffc900031479f0 EFLAGS: 00000046 RAX: 000000000000003e RBX: ffff8880b8523a00 RCX: 0000000000000838 RDX: 0000000000000000 RSI: 000000000000003e RDI: 0000000000000038 RBP: 000000000000003e R08: 0000000000000005 R09: 000000000000003f R10: 0000000000000020 R11: ffffffff9b0d2580 R12: dffffc0000000000 R13: 0000000000000000 R14: 0000000000000020 R15: ffffed10170a4745 FS: 0000555558775500(0000) GS:ffff8881247bc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c00732e000 CR3: 0000000077210000 CR4: 00000000003526f0 Call Trace: apic_write arch/x86/include/asm/apic.h:405 [inline] lapic_next_event+0x10/0x20 arch/x86/kernel/apic/apic.c:416 clockevents_program_min_delta+0x173/0x3a0 kernel/time/clockevents.c:248 clockevents_program_event+0x2a6/0x380 kernel/time/clockevents.c:336 tick_program_event+0xa9/0x140 kernel/time/tick-oneshot.c:44 __hrtimer_reprogram kernel/time/hrtimer.c:685 [inline] __hrtimer_reprogram kernel/time/hrtimer.c:659 [inline] hrtimer_reprogram+0x27b/0x450 kernel/time/hrtimer.c:868 hrtimer_start_range_ns+0x9d4/0xfc0 kernel/time/hrtimer.c:1330 __posixtimer_deliver_signal kernel/time/posix-timers.c:322 [inline] posixtimer_deliver_signal+0x30d/0x6b0 kernel/time/posix-timers.c:348 dequeue_signal+0x307/0x520 kernel/signal.c:660 get_signal+0x602/0x26d0 kernel/signal.c:2914 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5114d8ebe9 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:00007ffcc5e18098 EFLAGS: 00000246 RAX: fffffffffffffffc RBX: 00000000000231ee RCX: 00007f5114d8ebe9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f5114fb5fac RBP: 0000000000000032 R08: 00007f5115bce000 R09: 00000012c5e1838f R10: 00007ffcc5e18190 R11: 0000000000000246 R12: 00007f5114fb5fac R13: 00007ffcc5e18190 R14: 0000000000023220 R15: 00007ffcc5e181b0 Tested on: commit: a1617343 skip the validate_mm() for stall test git tree: git://git.infradead.org/users/jedix/linux-maple.git no_validate console output: https://syzkaller.appspot.com/x/log.txt?x=13441fbc580000 kernel config: https://syzkaller.appspot.com/x/.config?x=d4703ac89d9e185a dashboard link: https://syzkaller.appspot.com/bug?extid=8785aaf121cfb2141e0d compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 Note: no patches were applied.