From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B61AD410D0B for ; Thu, 26 Feb 2026 18:25:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772130319; cv=none; b=LltvcvRGGbO+jJ+qcm9JdH/2bGmIm3opuBkW6QiL3mvR25NNxF7jp4M4r+rYOqk+ogLfhH233gzK29+Iw2iYXf9smq78kaEnBbQqU6wqcZtvvEoN6zzwRoQDrN00viNw6Bbl9eTbZbKVyoCGUAuK+rlZlQg0MvhctpXs5a81jSg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772130319; c=relaxed/simple; bh=jfMff4Gl6e4MBoQvWfFtpIMIZ+n9o8V8+kADuSP57iw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uYUAdLp0sWZ4mlMd4vBVY3KOgVeuSf+vAr56sQymD56TAqJAbhVtwj06pC3+alm+ypf/ixEZznnz5oe/Fae2DkCudtc2fQF+7+DvIsfCocq+MqgAV9jTK+jUJDYTct333VjpaC9VNSG4ExJ0+1EybnvCnZ+Xk3SprdKJR+DLm8g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NOwhH9eg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NOwhH9eg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFC77C116C6; Thu, 26 Feb 2026 18:25:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772130319; bh=jfMff4Gl6e4MBoQvWfFtpIMIZ+n9o8V8+kADuSP57iw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NOwhH9egiNcn+t7MqkfmuYBcFV91Tw8sbA3d7EinxbrxVe3N7i6KNwIblL2NP7Azm 5bdy0mgPas/gv4JdSL1aSqAyNsw/7fmHEDRYem6myikiwWFyp47uSHhJb8Mik/FUld 1KzshbwFSi7WCZSSVH6OoBGFxVYJck305FoIw7eqbbRbkjYVas73i2gZoe6okP2TPT uTH1Z0H1dzgDogMAadc447coWUa9UItt8Ar16QaYfAZH/MSR7yAG0EowuRr0WMWVXw rXaAXEy6TCH1RfY1AhJs9S3hPNUXGB81GYkeD4IYD4lL6QWSSNtKxmDcSr9eAqFKK0 KtFEx+n/2GQIQ== Date: Thu, 26 Feb 2026 18:25:14 +0000 From: Will Deacon To: syzbot Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, maz@kernel.org Subject: Re: [syzbot] [arm?] BUG: using __this_cpu_read() in preemptible code in __delay Message-ID: References: <69a06135.050a0220.305b49.0024.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <69a06135.050a0220.305b49.0024.GAE@google.com> On Thu, Feb 26, 2026 at 07:05:25AM -0800, syzbot wrote: > syzbot found the following issue on: > > HEAD commit: 32a92f8c8932 Convert more 'alloc_obj' cases to default GFP.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1019fc02580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=b77d736d2f4fe1b1 > dashboard link: https://syzkaller.appspot.com/bug?extid=b29d18a34746f34c94cc > compiler: aarch64-linux-gnu-gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 > userspace arch: arm64 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/fa3fbcfdac58/non_bootable_disk-32a92f8c.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/aabf4d7d9d6a/vmlinux-32a92f8c.xz > kernel image: https://storage.googleapis.com/syzbot-assets/0367e274b699/Image-32a92f8c.gz.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+b29d18a34746f34c94cc@syzkaller.appspotmail.com > > BUG: using __this_cpu_read() in preemptible [00000000] code: syz.0.1012/5537 > caller is __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64 > CPU: 0 UID: 0 PID: 5537 Comm: syz.0.1012 Tainted: G L syzkaller #0 PREEMPT > Tainted: [L]=SOFTLOCKUP > Hardware name: linux,dummy-virt (DT) > Call trace: > show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:499 (C) > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x7c/0xb0 lib/dump_stack.c:120 > dump_stack+0x1c/0x28 lib/dump_stack.c:129 > check_preemption_disabled+0xe0/0xe8 lib/smp_processor_id.c:47 > __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64 > __arch_counter_get_cntvct_stable arch/arm64/include/asm/arch_timer.h:195 [inline] > __delay+0x40/0x374 arch/arm64/lib/delay.c:39 > __const_udelay+0x48/0x64 arch/arm64/lib/delay.c:66 > udelay include/asm-generic/delay.h:62 [inline] This should be fixed by the first patch in this series: https://lore.kernel.org/r/20260226082234.26707-1-maz@kernel.org I'll queue that today. Will #syz fix: arm64: Fix sampling the "stable" virtual counter in preemptible section