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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7EBE2C43458 for ; Sat, 11 Jul 2026 05:32:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 709D96B0005; Sat, 11 Jul 2026 01:32:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 693EC6B0088; Sat, 11 Jul 2026 01:32:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 55BB56B008A; Sat, 11 Jul 2026 01:32:25 -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 313BA6B0005 for ; Sat, 11 Jul 2026 01:32:25 -0400 (EDT) Received: from smtpin05.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id AB5DD4064C for ; Sat, 11 Jul 2026 05:32:24 +0000 (UTC) X-FDA: 84975375408.05.71C0E94 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by imf05.hostedemail.com (Postfix) with ESMTP id D5808100005 for ; Sat, 11 Jul 2026 05:32:22 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=deige75K; spf=pass (imf05.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 as permitted sender) smtp.mailfrom=qi.zheng@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=1783747943; 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=G5NmJY2iw9mr7LiD+wBGyisuFVRNUZ+aiJ7vkuUhCAE=; b=Xo8TyscrdAXZzSn7u/A53U5K4CmS+ya/Ifobq3YfnDJB4fs6COkg9nkLrE7LNgOzfvUM30 u21YbPJlwOA7XNR8+/Wkuzv8wLx1sMcleJ5rUwiyouHgSwhptAQU7lk5PaRSoElid7C9+2 bc9fQKMOP6fdr029q7Lo3kWbOMHV4wU= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=deige75K; spf=pass (imf05.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783747943; b=MkVg5NqTxZVOmrcPXQzHgbCoQErgO/lKxv4oQDTIhxe6KkzOsIzFGwF+8ohSTkhj4RVX0J chTxq6gVSYxXH7MCx6Dvl0hSuB6AY0bernaicjSjWtEfSM0peCvt+FYan2NehK+/lbALPE 9lkh9ud+ok3iTE1+Nlh/kcENCkpWrUo= Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1783747940; 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=G5NmJY2iw9mr7LiD+wBGyisuFVRNUZ+aiJ7vkuUhCAE=; b=deige75KcMd91XGDV/xznNzEracNWg8yXfEIAK9/OOOe8uqF1uoLyRtIg5SSGFwX2AQ8jc WqXflyjQsmlcZq67w+XQRJVVFQ4k2yAoCA5Pj3Ag6IHox67Nho1Z+EK2liTxHbD25RhjwS 8hKFh1eTpSfmQhoXQoLcCR3KpQ6sEZA= Date: Sat, 11 Jul 2026 13:31:47 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] mm: shrinker: Fix double-free in alloc_shrinker_info error path To: Hongling Zeng , akpm@linux-foundation.org, david@fromorbit.com, roman.gushchin@linux.dev, muchun.song@linux.dev Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, zhongling0719@126.com, stable@vger.kernel.org References: <20260711041954.95749-1-zenghongling@kylinos.cn> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <20260711041954.95749-1-zenghongling@kylinos.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D5808100005 X-Stat-Signature: 4t1eorwitf31kuqfptztf4syzw6zk1yp X-HE-Tag: 1783747942-131605 X-HE-Meta: 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 v0RQg0QO DoIu42AIbyN7YbnlR2OCoPliC6hNkz93INaavf/T+zqXId3PSwJtARK6DdlZBPsSQnFdNU9vLJlUczhg84y215uPwQlvMbaJq0zrk6I1f9qDq9cjxq/avpnGajUiENLAyyoWO0s+WOb6UkW3X7bawBOO/9ShYa/zdLaWqobhJU/2KhBh8pdBQk+pgfsk2LL49xqzZswqpci/yZPxRwk/6BXwNc/tEFAHPFU88mqhE9+Xbf5TEMpoqGHgtqGGUNjl0wS8RGcRKDjHXbD/vdNjPt1EAMA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Hongling, On 7/11/26 12:19 PM, Hongling Zeng wrote: > In alloc_shrinker_info(), when shrinker_unit_alloc() fails for a node, > the error handler calls free_shrinker_info() which iterates over ALL > nodes and tries to free their shrinker_info. For the failed node, > rcu_assign_pointer() was skipped, so its shrinker_info still points > to old data. This causes double-free of valid shrinker_info structures. No, it will be NULL, not old data. Therefore, the double-free you mentioned doesn't exist. Before sending the fix, please verify the problem exists and your fix actually works. And as a reminder, please don't repeatedly send identical patches: 1. https://lore.kernel.org/all/20260711041509.92926-1-zenghongling@kylinos.cn/ 2. https://lore.kernel.org/all/20260711041823.95135-1-zenghongling@kylinos.cn/ 3. https://lore.kernel.org/all/20260711041954.95749-1-zenghongling@kylinos.cn/ One last thing, please make sure to base your changes on the latest tree. Thanks, Qi > > Fix by tracking which node failed and only freeing shrinker_info > structures that were successfully assigned via rcu_assign_pointer() > in this call. Failed/unhandled nodes are left untouched. > > Fixes: 15e8156713cc ("mm: shrinker: avoid memleak in alloc_shrinker_info") > Cc: stable@vger.kernel.org > Signed-off-by: Hongling Zeng > --- > mm/shrinker.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/mm/shrinker.c b/mm/shrinker.c > index 7082d01c8c9d..92c6cb455fc9 100644 > --- a/mm/shrinker.c > +++ b/mm/shrinker.c > @@ -78,6 +78,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) > { > int nid, ret = 0; > int array_size = 0; > + int failed_nid; > > mutex_lock(&shrinker_mutex); > array_size = shrinker_unit_size(shrinker_nr_max); > @@ -98,8 +99,18 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) > return ret; > > err: > + failed_nid = nid; > + for_each_node(nid) { > + struct shrinker_info *info; > + > + if (nid >= failed_nid) > + break; > + info = shrinker_info_protected(memcg, nid); > + rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, NULL); > + shrinker_unit_free(info, 0); > + kvfree(info); > + } > mutex_unlock(&shrinker_mutex); > - free_shrinker_info(memcg); > return -ENOMEM; > } >