From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9A16CA0EEB for ; Tue, 19 Aug 2025 15:30:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7EA0A8E0023; Tue, 19 Aug 2025 11:30:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7C2078E0007; Tue, 19 Aug 2025 11:30:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7006B8E0023; Tue, 19 Aug 2025 11:30:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 5934B8E0007 for ; Tue, 19 Aug 2025 11:30:57 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 2193C585C2 for ; Tue, 19 Aug 2025 15:30:57 +0000 (UTC) X-FDA: 83793894954.17.C31FF49 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf22.hostedemail.com (Postfix) with ESMTP id B8966C0008 for ; Tue, 19 Aug 2025 15:30:55 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none); spf=pass (imf22.hostedemail.com: domain of cmarinas@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=cmarinas@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755617455; a=rsa-sha256; cv=none; b=rzdbukM3TPV8uzRFlHxQ4O5KXPijhh55zUBIylp2YW/e2pOWu0saHasDmD5WGANPArtb9l bgLFYDdGVzuCbwtJ2RVTGht+NTKM8m2+Fr7wE4fgiiK/yBOCm/CHEQA7zeQK++Twz/D1tr MG97TjkELi8PocAYYhA7kydlZlL2jY4= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none); spf=pass (imf22.hostedemail.com: domain of cmarinas@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=cmarinas@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755617455; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2e9n1br5LLALvMcnjB2cBa8bX5b7dKNPs6WqYF8aw7E=; b=XtD4oA+5Hap4rVp0zu/lIPl0JW+ytm6WNJXSCgv7lC2NA7MOv0WNF7hJxo4IQYUBX231fx 9Lo6aHRicl74EbpXHIFsQE86PV4BUhgnvhSGru/OCuTdYgmcVi2jEiADOar41ngbTBKc84 P7O7LdRMk7J5KFxt2kVKLPWkFdchCpw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 17A9160209; Tue, 19 Aug 2025 15:30:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 202F6C4CEF1; Tue, 19 Aug 2025 15:30:52 +0000 (UTC) Date: Tue, 19 Aug 2025 16:30:51 +0100 From: Catalin Marinas To: Gu Bowen Cc: Andrew Morton , Greg Kroah-Hartman , stable@vger.kernel.org, linux-mm@kvack.org, Waiman Long , Breno Leitao , John Ogness , Lu Jialin Subject: Re: [PATCH v4] mm: Fix possible deadlock in kmemleak Message-ID: References: <20250818090945.1003644-1-gubowen5@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250818090945.1003644-1-gubowen5@huawei.com> X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: B8966C0008 X-Stat-Signature: u1jqz6htrjjsrrgzo7jr6qxd8iyo1p8r X-HE-Tag: 1755617455-872304 X-HE-Meta: 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 4BH2jeWR CQmC4p3ezZLtYO4GmDM/eCDI4KeA/BF0LE9DiEXttzdi5tlsLrRWtekWypbfu+uVRacPN X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 18, 2025 at 05:09:44PM +0800, Gu Bowen wrote: > Our syztester report the lockdep WARNING [1], which was identified in > stable kernel version 5.10. However, this deadlock path no longer exists > due to the refactoring of console_lock in v6.2-rc1 [2]. Coincidentally, > there are two types of deadlocks that we have found here. One is the ABBA > deadlock, as mentioned above [1], and the other is the AA deadlock was > reported by Breno [3]. The latter's deadlock issue persists. It's better to include the lockdep warning here rather than linking to other threads. Also since we are targeting upstream with this patch, I don't think we should mention lockdep warnings for 5.10. > To solve this problem, switch to printk_safe mode before printing warning > message, this will redirect all printk()-s to a special per-CPU buffer, > which will be flushed later from a safe context (irq work), and this > deadlock problem can be avoided. The proper API to use should be > printk_deferred_enter()/printk_deferred_exit() [4]. > > [1] > https://lore.kernel.org/all/20250730094914.566582-1-gubowen5@huawei.com/ > [2] > https://lore.kernel.org/all/20221116162152.193147-1-john.ogness@linutronix.de/ > [3] > https://lore.kernel.org/all/20250731-kmemleak_lock-v1-1-728fd470198f@debian.org/#t > [4] > https://lore.kernel.org/all/5ca375cd-4a20-4807-b897-68b289626550@redhat.com/ > ==================== > > Signed-off-by: Gu Bowen > --- I suggest you add the 5.10 mention here if you want, text after "---" is normally stripped (well, not sure with Andrew's scripts). Otherwise the patch looks fine. Reviewed-by: Catalin Marinas