From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 12FDC17A5BD for ; Mon, 2 Sep 2024 08:26:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725265574; cv=none; b=hxzBdY8nv6l9AbVyXUYUbueyfH8W5bOHbNib5PE2wooYgAl8w5k4W5ppL88h9pnOQVvWsc9OHrB0wt8sEeDBnOSxZbCmYu1HBBQvQ8qWl2Xt7Rl6bMYA8C12bUcAFiYKtgcV9+MZm54LrBqer9ysUMgMRiGyP/mVpwMLnZtc2Cw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725265574; c=relaxed/simple; bh=nmBl9sAHM51BZJE4rFRSUamfaIahwDY3T+X4Ktf45lM=; h=From:To:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=h1ZHPaEq5FGJq2JrdA6vt7I1Dd32Vy8ON8jXEK8lpmgoBTK4FGAouA3x545NIA3njg1rthniGj4mdZBtZ1VXTu1fSbJbD9/BY6GXN6GVqLnj8PounrZfyVOJB1fH13wcwMbwJk6Af6Y3QE46IzXBA5TGTcYdkjet2eG/5rPE23g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=DeBXiyC4; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=y4MVeBj5; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="DeBXiyC4"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="y4MVeBj5" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1725265571; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eF3PvzqmwhOKgO+9ni5+AK2f9itfVksLzdm/qhifh6I=; b=DeBXiyC4ZxrYXXWnKTV3MGdOeArOSdWxEMcAWa8H8TBRxdj7N8AiXTlO82qjNACX86YwZB Myhfc7MHSgRKA8NdyFLiEQQcv+98ABUs4Y5F5XcQakOwQbJ1eQErVmJIVZSpn/iUKtbtB2 EDSeugzvMCxjUFYYmAfw5zqRfUe4Fbpy+Ovz66RbaenWQpklKsGZ0LbVPl2ZqCeQdEVEjd UB28/YLCz/7OyIE2hF4rA0wZglOhVxlRGbmd598e1eKUrM31Q6T6/Ucg+6i8GUHxlXkIz5 WprGhsPBpNlEbv62eBknXLVvMEeHPvaKlRKIM5e4KGk26PeNVK+Z0Hdfxvwrmw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1725265571; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eF3PvzqmwhOKgO+9ni5+AK2f9itfVksLzdm/qhifh6I=; b=y4MVeBj5OeAiajLIaOFICxqRQDiGFdtf/hSu2l3RC5UdNdTVpPCWyPkgv2zenQE0r+MKud T6DZd3UAHUtX/bAA== To: syzbot , linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, x86@kernel.org, linux-mm@kvack.org Subject: Re: [syzbot] [kernel?] KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn (2) In-Reply-To: <000000000000d47d440620d54f15@google.com> References: <000000000000d47d440620d54f15@google.com> Date: Mon, 02 Sep 2024 10:26:10 +0200 Message-ID: <87le0a797h.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Aug 29 2024 at 09:53, syzbot wrote: Cc-: x86 folks. Just because something happens on x86 does not mean it's an x86 problem Cc+: mm folks. It's entirely clear where this belongs to: > read-write to 0xffffffff88bb27ac of 4 bytes by task 3354 on cpu 0: > pcpu_update_empty_pages mm/percpu.c:602 [inline] No? > Hello, > > syzbot found the following issue on: > > HEAD commit: d5d547aa7b51 Merge tag 'random-6.11-rc6-for-linus' of git:.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=164c067b980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=6fafac02e339cc84 > dashboard link: https://syzkaller.appspot.com/bug?extid=6d392a44667baa45bb5a > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/e636aa58c364/disk-d5d547aa.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/f5ecd0d96afa/vmlinux-d5d547aa.xz > kernel image: https://storage.googleapis.com/syzbot-assets/fe7d474f148f/bzImage-d5d547aa.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+6d392a44667baa45bb5a@syzkaller.appspotmail.com > > ================================================================== > BUG: KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn > > read-write to 0xffffffff88bb27ac of 4 bytes by task 3354 on cpu 0: > pcpu_update_empty_pages mm/percpu.c:602 [inline] > pcpu_chunk_populated mm/percpu.c:1531 [inline] > pcpu_balance_populated mm/percpu.c:2062 [inline] > pcpu_balance_workfn+0x94e/0xa60 mm/percpu.c:2212 > process_one_work kernel/workqueue.c:3231 [inline] > process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312 > worker_thread+0x526/0x6e0 kernel/workqueue.c:3389 > kthread+0x1d1/0x210 kernel/kthread.c:389 > ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > read to 0xffffffff88bb27ac of 4 bytes by task 6821 on cpu 1: > pcpu_alloc_noprof+0x9a7/0x10c0 mm/percpu.c:1894 > bpf_map_alloc_percpu+0xad/0x210 kernel/bpf/syscall.c:466 > prealloc_init+0x19f/0x470 kernel/bpf/hashtab.c:341 > htab_map_alloc+0x630/0x8e0 kernel/bpf/hashtab.c:576 > map_create+0x83c/0xb90 kernel/bpf/syscall.c:1333 > __sys_bpf+0x667/0x7a0 kernel/bpf/syscall.c:5692 > __do_sys_bpf kernel/bpf/syscall.c:5817 [inline] > __se_sys_bpf kernel/bpf/syscall.c:5815 [inline] > __x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5815 > x64_sys_call+0x2625/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:322 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > value changed: 0x00000001 -> 0x00000004 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 1 UID: 0 PID: 6821 Comm: syz.4.1651 Not tainted 6.11.0-rc5-syzkaller-00081-gd5d547aa7b51 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup