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 03271C2BD09 for ; Fri, 12 Jul 2024 04:29:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8F9D46B009E; Fri, 12 Jul 2024 00:29:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A88B6B00A2; Fri, 12 Jul 2024 00:29:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7985A6B00A3; Fri, 12 Jul 2024 00:29:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 588A26B009E for ; Fri, 12 Jul 2024 00:29:20 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 033D7160900 for ; Fri, 12 Jul 2024 04:29:19 +0000 (UTC) X-FDA: 82329821280.22.EA723B3 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) by imf11.hostedemail.com (Postfix) with ESMTP id A8B7940024 for ; Fri, 12 Jul 2024 04:29:17 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=i+TvpkiE; spf=pass (imf11.hostedemail.com: domain of youling.tang@linux.dev designates 91.218.175.177 as permitted sender) smtp.mailfrom=youling.tang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1720758524; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=91kt2GmWN9YbpB1swLWRn5wi5i5GBzkMGgIhKOw2Kfg=; b=Bn9AyfAB+d6w5Wcz63gjDVhmQpri7mzxnJCvFlXbO6YxTF3gWBzW7SUGOerhgnc5NqZiWx gqHSLLuU9WpI92OzGeUywKIQofKP6gUWoj79gQ6waBTAf6aIN2NMhZu/1xu1Ustp7qabEr IolluKd6Gn/eKKaSVbZ3oU6Q1twV6kc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1720758524; a=rsa-sha256; cv=none; b=DtijwnM+IeTVdXwkk1uRXR7V7wF1Z7LU3YFSI9U2hSMjUrS2WHcV+YDNhX49dhSxV/vPfT 24c3R3dARRjvBcTFe84jlLXUldkSdn+kwUR4eX7zTsdMtBG/j87pyVdvvuAj4NJL9OelOX 9ygDbjdTB1EvN9+5/Cb4O3v8M53cfcY= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=i+TvpkiE; spf=pass (imf11.hostedemail.com: domain of youling.tang@linux.dev designates 91.218.175.177 as permitted sender) smtp.mailfrom=youling.tang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Envelope-To: kent.overstreet@linux.dev DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1720758556; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=91kt2GmWN9YbpB1swLWRn5wi5i5GBzkMGgIhKOw2Kfg=; b=i+TvpkiEJn2vxXXHEwy5YpK5gI3DkJj87abjO3vdr214Fu8eMfTvHm8c4hlgZtnOa9eglb mBReAbnoytCvfYX66aNAU0t3C9t6W4s+gRR7lKHRc6ujF/oOYj+A5XyxKI/XoyrQDoM1pX 8iBo+mXhrhIOd4G4ZEGKNNs+YGkcMM4= X-Envelope-To: akpm@linux-foundation.org X-Envelope-To: linux-mm@kvack.org X-Envelope-To: linux-kernel@vger.kernel.org X-Envelope-To: tangyouling@kylinos.cn Message-ID: <8ce42a2e-783f-4244-8e75-21dcd578adf5@linux.dev> Date: Fri, 12 Jul 2024 12:28:57 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] mm: list_lru: Fix NULL pointer dereference in list_lru_add() To: Kent Overstreet Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Youling Tang References: <20240712032554.444823-1-youling.tang@linux.dev> Content-Language: en-US, en-AU X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Youling Tang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A8B7940024 X-Stat-Signature: urdytpkrx585agh9y5caotpujfqsntm5 X-HE-Tag: 1720758557-477752 X-HE-Meta: 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 K1FRTr6O Oq5NuPjv8wkT4T4abOhjBMEg9bXU7sFJXGsp4v+GHUnTrUCS50BeAZ4Tl7Jp85fM1bWWYkpNYhOf3CvFBKRlRwdNaW7GUmEVJIARu+UczO4+gRLdkqA7EB3p3Ju/QKWEF5DZ0TYyAVORlvKI9kjtVEaAW0sRuR4A3oGYhfhgr6mVdDC493LgyL5xkc6viVmGZXK17g1qdZQcThcqcWUIJmyNCKKwzcONNbUnu0/SkeKZvQNV6W7Mdp/U+XcMF3ysL36TQ 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: Hi, Kent On 12/07/2024 12:07, Kent Overstreet wrote: > On Fri, Jul 12, 2024 at 11:25:54AM GMT, Youling Tang wrote: >> From: Youling Tang >> >> Note that list_lru_from_memcg_idx() may return NULL, so it is necessary >> to error handle the return value to avoid triggering NULL pointer >> dereference BUG. >> >> The issue was triggered for discussion [1], >> Link [1]: https://lore.kernel.org/linux-bcachefs/84de6cb1-57bd-42f7-8029-4203820ef0b4@linux.dev/T/#m901bb26cdb1d9d4bacebf0d034f0a5a712cc93a6 > I see no explanation for why this is the correct fix, and I doubt it is. > What's the real reason for the NULL lru_list_one, and why doesn't this > come up on other filesystems? We can break it down into two questions (independent of each other): 1) Error handling is necessary when l (lru_list_one) is NULL here. 2) Why does marking SLAB_ACCOUNT in bcachefs cause lru_list_one    to be NULL? This patch only fixes the first issue, and the real cause of the second issue still needs to be analyzed. Thanks, Youling.