From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A075D34CDD; Thu, 5 Feb 2026 01:50:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770256229; cv=none; b=Mh1ogF6W7TNX5CTPXQXsbPz4m4pmdX1kPhZcpVuzQGjWHj7EQJQWgepzBFpN8k0lt3S578O7+ifBZKRgMCaMepeDLYzYwjMueCu1km8kLLyfTItCE4BIxd+8hT9q7B10BKN088mCB02kP4XQPAgKI/Z9FS20WznGi90Rlhb3fks= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770256229; c=relaxed/simple; bh=nPRY4vVJAIFccVMk8CH+5lvP9L8860L47h2sDG4AXlU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jr7oJU7yFoEQdzAUyD0Qf3GCMlmFKFXdUI8QaXRWmsDtfT+UemDL/rCNEUtRMAkzklNIx8KQN1k2xLiHFHjdLScl+z0EDMqmsQzqUm1/+bOVzv778Q1zAgi/LrcnTWVwN6v83GMgkqNse6QT+Y4UEiVuF7mf6PGtKK/Ag1c2YLI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=BCV+BkvT; arc=none smtp.client-ip=192.198.163.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="BCV+BkvT" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1770256229; x=1801792229; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=nPRY4vVJAIFccVMk8CH+5lvP9L8860L47h2sDG4AXlU=; b=BCV+BkvT4+zh8KdA3jRaKRPp1F9W22R/0nq2T3ZbqCmXA1EAY8+jiE4A FyVI3QaN9/iFqLE1UJn6EXtzF0XPKqV/rGPbktb1Qe/8NihQzBeHA1540 Plh5vqgzTy/jxuIWSL5hnHgtXIV4VfT7CUorxVfIg1EEWlalN9nmw8K5p A3HpxeYAGwuXaUxIymmAUrjxxXw4sqctGzqhKXb7v+3/NVQJ07x3+IcwW 7PMrL8vTQpHgofwlmQktTXdwNya0CA0rTmnIWQp369hXLltxrHKpsKWhy Qevrd21s6Bw/pmI3xF1s++y3IJie9GVp7YFktg8kFT9VN92WIxg95/tvk g==; X-CSE-ConnectionGUID: JTiPRyX3TkWUZ7H7H7a++Q== X-CSE-MsgGUID: V74WsJkjTyKP7ASKH+rudQ== X-IronPort-AV: E=McAfee;i="6800,10657,11691"; a="82190174" X-IronPort-AV: E=Sophos;i="6.21,273,1763452800"; d="scan'208";a="82190174" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Feb 2026 17:50:28 -0800 X-CSE-ConnectionGUID: bzN0Ael8TmOEOtG8q/o2qg== X-CSE-MsgGUID: FxNw+gg/T9CLnkOK61wowA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,273,1763452800"; d="scan'208";a="209634401" Received: from unknown (HELO [10.238.0.190]) ([10.238.0.190]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Feb 2026 17:50:25 -0800 Message-ID: <5a8b9593-d458-474d-b084-3c2374b1c039@linux.intel.com> Date: Thu, 5 Feb 2026 09:50:23 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [WARNING] WARNING in x86_pmu_stop() (arch/x86/events/core.c:1624) triggered by syzkaller repro To: =?UTF-8?B?5piv5Y+C5beu?= , "linux-perf-users@vger.kernel.org" , "x86@kernel.org" Cc: "linux-kernel@vger.kernel.org" , "peterz@infradead.org" , "dave.hansen@linux.intel.com" , "bp@alien8.de" , "acme@kernel.org" References: Content-Language: en-US From: "Mi, Dapeng" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Thanks for reporting this issue. I would look at it later. On 2/4/2026 9:11 PM, 是参差 wrote: > Hi, > I’m reporting a reproducible WARNING observed in the x86 perf PMU stop path. > The WARNING is triggered by a syzkaller C reproducer that performs multiple perf_event_open() calls with high-frequency sampling settings and then exercises a workload that heavily hits perf/tracepoint paths (e.g., sched tracepoints). The kernel hits a WARN in x86_pmu_stop() while handling perf event throttling/overflow. > The WARNING report points to: > WARNING: arch/x86/events/core.c:1624 at x86_pmu_stop+0x247/0x260, CPU#0: syz.2.7419/25339 > Call trace (trimmed to the perf-relevant part): > perf_event_throttle.part.0 > __perf_event_account_interrupt > __perf_event_overflow > perf_swevent_overflow > perf_swevent_event > perf_tp_event > perf_trace_run_bpf_submit > perf_trace_sched_stat_runtime > ... > This suggests a possible state-machine inconsistency or corner-case interaction between the perf throttling/overflow handling and the x86 PMU stop path (x86_pmu_stop()), potentially triggered by an unusual perf_event_attr combination and high event rate. > Reproducer: > C reproducer: https://pastebin.com/raw/t9u91hQf > console output: https://pastebin.com/raw/XUw5zuQg > kernel config: https://pastebin.com/raw/dP93yBLn > Kernel: > git tree: torvalds/linux > kernel version: 6.19.0-rc7 #1 VOLUNTARY (QEMU Ubuntu 24.10) > HEAD commit:63804fed149a6750ffd28610c5c1c98cce6bd377 > > > > EXT4-fs (loop2): mounting ext3 file system using the ext4 subsystem > EXT4-fs (loop2): 1 truncate cleaned up > EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none. > ------------[ cut here ]------------ > WARNING: arch/x86/events/core.c:1624 at x86_pmu_stop+0x247/0x260 arch/x86/events/core.c:1624, CPU#0: syz.2.7419/25339 > CPU: 0 UID: 0 PID: 25339 Comm: syz.2.7419 Not tainted 6.19.0-rc7 #1 VOLUNTARY > Hardware name: QEMU Ubuntu 24.10 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > RIP: 0010:x86_pmu_stop+0x247/0x260 arch/x86/events/core.c:1624 > Code: 4c 89 ef e8 9b 59 6e 00 e9 48 ff ff ff 4c 89 ef e8 2e 5a 6e 00 eb 85 4c 89 e7 e8 84 59 6e 00 e9 83 fe ff ff e8 6a 99 3e 00 90 <0f> 0b 90 e9 44 ff ff ff 4c 89 e7 e8 69 59 6e 00 eb 96 0f 1f 80 00 > RSP: 0018:ffff88800bebe868 EFLAGS: 00010012 > RAX: 000000000000797b RBX: ffff888010488000 RCX: ffffc90000390000 > RDX: 0000000000080000 RSI: ffff88802e495640 RDI: 0000000000000002 > RBP: 0000000000000000 R08: ffffffff87073701 R09: ffffffff8120c1a6 > R10: 0000000000000001 R11: ffffffff86e3a6c7 R12: 0000000000000001 > R13: ffff8880104881f8 R14: 0000000000000001 R15: 0000000000000000 > FS: 00007f99e6c976c0(0000) GS:0000000000000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000200000002000 CR3: 000000005f659000 CR4: 0000000000350ef0 > DR0: 0000200000000080 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 > Call Trace: > > perf_event_throttle.part.0+0x89/0xf0 kernel/events/core.c:2682 > perf_event_throttle kernel/events/core.c:2678 [inline] > perf_event_throttle_group kernel/events/core.c:2700 [inline] > __perf_event_account_interrupt+0x2a6/0x430 kernel/events/core.c:10258 > __perf_event_overflow+0xb6/0xa00 kernel/events/core.c:10405 > perf_swevent_overflow+0xac/0x150 kernel/events/core.c:10545 > perf_swevent_event+0x14d/0x2e0 kernel/events/core.c:10583 > perf_tp_event+0x3b7/0x810 kernel/events/core.c:11090 > perf_trace_run_bpf_submit+0xef/0x180 kernel/events/core.c:11014 > do_perf_trace_sched_stat_runtime include/trace/events/sched.h:553 [inline] > perf_trace_sched_stat_runtime+0x360/0x680 include/trace/events/sched.h:553 > __do_trace_sched_stat_runtime include/trace/events/sched.h:576 [inline] > trace_sched_stat_runtime include/trace/events/sched.h:576 [inline] > update_se+0x39b/0x480 kernel/sched/fair.c:1159 > update_curr+0x71/0x450 kernel/sched/fair.c:1209 > put_prev_entity+0x97/0x1b0 kernel/sched/fair.c:5504 > pick_next_task_fair+0xf7e/0x17b0 kernel/sched/fair.c:8949 > __pick_next_task kernel/sched/core.c:5890 [inline] > pick_next_task kernel/sched/core.c:6426 [inline] > __schedule+0x740/0x1df0 kernel/sched/core.c:6809 > preempt_schedule_common kernel/sched/core.c:7051 [inline] > __cond_resched+0x45/0x70 kernel/sched/core.c:7378 > mutex_lock+0x75/0xe0 kernel/locking/mutex.c:287 > ext4_mb_group_or_file fs/ext4/mballoc.c:5886 [inline] > ext4_mb_initialize_context+0x85e/0xcf0 fs/ext4/mballoc.c:5930 > ext4_mb_new_blocks+0x603/0x3fc0 fs/ext4/mballoc.c:6304 > ext4_alloc_branch fs/ext4/indirect.c:340 [inline] > ext4_ind_map_blocks+0x1635/0x20c0 fs/ext4/indirect.c:635 > ext4_map_create_blocks fs/ext4/inode.c:615 [inline] > ext4_map_blocks+0xb51/0x1350 fs/ext4/inode.c:816 > _ext4_get_block+0x1bb/0x550 fs/ext4/inode.c:916 > ext4_block_write_begin+0x88a/0x1040 fs/ext4/inode.c:1203 > ext4_write_begin+0x75f/0x11d0 fs/ext4/inode.c:1364 > generic_perform_write+0x37d/0x800 mm/filemap.c:4314 > ext4_buffered_write_iter+0x11a/0x430 fs/ext4/file.c:299 > ext4_file_write_iter+0x560/0x1790 fs/ext4/file.c:723 > new_sync_write fs/read_write.c:593 [inline] > vfs_write fs/read_write.c:686 [inline] > vfs_write+0xa66/0xe30 fs/read_write.c:666 > ksys_write+0x120/0x240 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xa9/0x320 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x4b/0x53 > RIP: 0033:0x7f99e822ebe9 > 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:00007f99e6c97038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 00007f99e8465fa0 RCX: 00007f99e822ebe9 > RDX: 000000000208e24b RSI: 0000200000000340 RDI: 000000000000000a > RBP: 00007f99e82b1e19 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007f99e8466038 R14: 00007f99e8465fa0 R15: 00007ffc60f336c8 > > ---[ end trace 0000000000000000 ]--- > > Thanks