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 27B78101E2 for ; Thu, 23 May 2024 22:32:47 +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=1716503569; cv=none; b=N5Uis7dQGV2J/TQAOwxMD8USKJueo5rkYI9XLL2K6qyYbAj6ozj8nvDzzTaVPswEEoBlVUIDi7eQbjaGhd2VKsf3zxF4qm7je+j12b896FhNMjQpbP0mkknEoKUttWx/nOACg2sxuPh1/GKBkLWH/TN8ogV9Kcm/zoBP3IJ7X8M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716503569; c=relaxed/simple; bh=w0yAmaXElVRuUzavPH0AzyMtrbdonziNp5Tcb9MGaHY=; h=From:To:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=m5cevW5jTQhl2ehtQBnggm3vF2h7HtAj4zQ5t6cmtvp9zJeIk3Hla1Kj5niUqC9EZAIYh1SV/WZNZQDQYMJQ1ixYD3uaOsS9mTPkf9W+r1aCAhW4wnluXH8vgW93/igwp1lM9dU3I0CeMp0rynVnYreS3UsqIMWIwfc6/GsLieo= 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=gq3kyfpz; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=m0EJq6Q3; 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="gq3kyfpz"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="m0EJq6Q3" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1716503566; 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=gcwhKwWiYkkvnly8C5LXaEQL7Q16QzdORDIjhnOhuyM=; b=gq3kyfpzkAMxNlWrSXHiO/lJ0kdC4Wi4ESKWucqD/5LEu5xs+wMsAZtX8mLDA9pfBJNGZy a2mRjuKBHte7t8StGqHF9Fk+kPTY7r8I3Cf0dFjcL/FUjRD9xjXqj6N0FDOIw3IFb4EsTt N2T26nbNuYx7iKRIDnGteZDvRkl2duANvHAVsoTTHRDkW4bl+adzkQwFEd0/+i2DA2swn9 0o+V4UgstK2eMM2DDBYIutQeltqqS9keNW5DONP42RqIIIwhRzkJEt/Nvx1uKDp+MKhh3G n9Q11MNbx/rtJ0lEwzwkJy9HVmjTa20j62/586hAVX/qJ3Wn1wPxBm6emGokVQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1716503566; 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=gcwhKwWiYkkvnly8C5LXaEQL7Q16QzdORDIjhnOhuyM=; b=m0EJq6Q3Bv+wtnC9MmrXKCodOcybz7kUd9Oz53glx+aoR1LP39QA2EAtMmnXBwuSIjXCtm AiCAbqN8xkwFAtAA== To: Vlastimil Babka , syzbot , bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com, syzkaller-bugs@googlegroups.com, x86@kernel.org, linux-mm@kvack.org, Sebastian Andrzej Siewior , Tejun Heo , Lai Jiangshan Subject: Re: [syzbot] [kernel?] WARNING in flush_cpu_slab In-Reply-To: <2149ee23-5321-4422-808f-e6a9046662fc@suse.cz> References: <0000000000008c9d27061915ca9c@google.com> <87v834g6hn.ffs@tglx> <2149ee23-5321-4422-808f-e6a9046662fc@suse.cz> Date: Fri, 24 May 2024 00:32:45 +0200 Message-ID: <87r0dsdur6.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, May 23 2024 at 23:03, Vlastimil Babka wrote: > On 5/23/24 12:36 PM, Thomas Gleixner wrote: >>> ------------[ cut here ]------------ >>> DEBUG_LOCKS_WARN_ON(l->owner) >>> WARNING: CPU: 3 PID: 5221 at include/linux/local_lock_internal.h:30 local_lock_acquire include/linux/local_lock_internal.h:30 [inline] >>> WARNING: CPU: 3 PID: 5221 at include/linux/local_lock_internal.h:30 flush_slab mm/slub.c:3088 [inline] >>> WARNING: CPU: 3 PID: 5221 at include/linux/local_lock_internal.h:30 flush_cpu_slab+0x37f/0x410 mm/slub.c:3146 > > I'm puzzled by this. We use local_lock_irqsave() on !PREEMPT_RT everywhere. > IIUC this warning says we did the irqsave() and then found out somebody else > already set the owner? But that means they also did that irqsave() and set > themselves as l->owner. Does that mey there would be a spurious irq enable > that didn't go through local_unlock_irqrestore()? > > Also this particular stack is from the work, which is scheduled by > queue_work_on() in flush_all_cpus_locked(), which also has a > lockdep_assert_cpus_held() so it should fullfill the "the caller must ensure > the cpu doesn't go away" property. But I think even if this ended up on the > wrong cpu (for the full duration or migrated while processing the work item) > somehow, it wouldn't be able to cause such warning, but rather corrupt > something else Indeed. There is another report which makes no sense either: https://lore.kernel.org/lkml/000000000000fa09d906191c3ee5@google.com Both look like data corropution issues caused by whatever... Thanks, tglx