From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B7C29606A320 for ; Wed, 28 Oct 2026 08:24:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=oKxKo39Y Received: by kanga.kvack.org (Postfix) id D91C36B05CE; Wed, 28 Oct 2026 04:24:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D69C06B05CF; Wed, 28 Oct 2026 04:24:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7F226B05D0; Wed, 28 Oct 2026 04:24:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 9ECB76B05CE for ; Wed, 28 Oct 2026 04:24:50 -0400 (EDT) Received: from smtpin09.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 98674160C31 for ; Wed, 28 Oct 2026 08:24:49 +0000 (UTC) X-FDA: 85371349098.09.4ABEFFD Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by imf06.hostedemail.com (Postfix) with ESMTP id 18358180005 for ; Wed, 28 Oct 2026 08:24:44 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=oKxKo39Y; spf=pass (imf06.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.130 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793175886; 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=nfoVrSYOIzxmSP8r27IFAd8Frmu7ylTcKW71rW773Fg=; b=irUU0+riLP4jxp2czLEcNQvIUUI+glNuvuZQJcJMZAO9Ti78oGmOwjnX8AfU406wMX6TZz oRaiwivaXeWdzFgAYYDS701WHq6as0UozL1pLVp44uECStQOZbQXWpZTF529URij31zZEA enhfS4dfWLXJzoMX1dfma1OOnPaBxCQ= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=oKxKo39Y; spf=pass (imf06.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.130 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793175886; b=gXiM6+O8QDUi4zJg+W6+G9IVSGEZWPqoJ7nvZbLQuWzN3ur/M9F/Z/3nZTKOSgCCoC9IPw g5i6PkY/jIlw97McBjWk6gW9Bcs+HCnwllDN+mFGMDD9AsZiFDmyphS1oy+xIUFLkZqWMi q761SwCwiAXnBHqdZZeRIxn8yPNeTfk= DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1793175881; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=nfoVrSYOIzxmSP8r27IFAd8Frmu7ylTcKW71rW773Fg=; b=oKxKo39YnjDecrJ9vQGt5VoDSJr5iOvdeo5dTF68P2GSUvraMmJwlYd+dqHwG1ST8U4ESsrSd6sR2qxP4vw15s2Lfn4N9GtulczSotGaEOzs7oDpySA4WoPu/Cdncu77y02zTC83CUvEhdJIWcY+5k7NanA0dseuJ82RI6lF09Q= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037033178;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=65;SR=0;TI=SMTPD_---0XDgGDMt_1793175874; Received: from 30.74.144.137(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XDgGDMt_1793175874 cluster:ay36) by smtp.aliyun-inc.com; Wed, 28 Oct 2026 16:24:37 +0800 Message-ID: Date: Wed, 28 Oct 2026 16:24:34 +0800 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/46] mm/mglru: don't use stack pointers when walking PUD and PMD tables To: "David Hildenbrand (Arm)" , Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Josef Bacik , stable@vger.kernel.org References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-1-6f74bec9a5bb@kernel.org> From: Baolin Wang In-Reply-To: <20261027-fixes_core-v1-1-6f74bec9a5bb@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 18358180005 X-Stat-Signature: g399n47wyngwazgehq6y3rgzgmjb8o5w X-Rspam-User: X-Spam-Status: No, score=-19.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1793175884-668837 X-HE-Meta: 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 /J0XOHSf o/y4DJQgCPSAXMuhM+rlrtA9IWEKX8FzAeF3QJ/RupoGMGw0VvljDYTIKVSDHLjwk8vbYjeP3HobgYtdJbRAfUZm3977v+iQ095t2UD8HKs1VYTe7uQHZ1vCKPPg6fC6+Qo+9JzLy+5v6ag41S91HnEjVs5jOHXTohrudcOBpMvJr9OhzXzi8EGJyjPwas6HZhY2tzXSjdnHKTq25JNCw4iqOgRRgcS7HoivvxQ96EkIjp6vJDw7xi2is3gIf78kBMBS+ZjQuGni1O3sPfMuzxpmPcj6XcJAPjjADyk60GBf55WmnDiEme26x8htwnq3fv2EaJH6rB3Sojo2tpSLpGaaP86HuoXix5nAYLhfduPqfm0mL+Fcrdrm32DXYALerkBJ5PvDla5ow/ZCBgGExu5YxDrZzuVbuXk9tfbDv9ZfZUkZgnWpxvRq6wS7bcK6RVi201c6WsaTv28Q= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/27/26 7:17 AM, David Hildenbrand (Arm) wrote: > From: Josef Bacik > > MGLRU passes stack copies of page-table entries in walk_pud_range() and > walk_pmd_range() when walking to the next level. These copies can become > stale when khugepaged or MADV_DONTNEED (CONFIG_PT_RECLAIM) removes a PTE > table concurrently. > > This pattern dates back to commit bd74fdaea146 ("mm: multi-gen LRU: > support page table walks"). Likely, earlier locking masked the latent > bug. Later changes exposed it: commit 1d65b771bc08 ("mm/khugepaged: > retract_page_tables() without mmap or vma lock") allowed concurrent > retraction, and commit cf4a65539c13 ("memcg-v1: no need for memcg locking > for MGLRU") dropped the walker's outer RCU protection. > > The fix is simple, so just fix the original commit so we don't have to > speculate. To fix it, pass the actual PMD/PUD pointers. This restores the > RCU-protected lookup and validation against the live PMD. Note that the PUD > handling is required as well to handle folded page tables correctly in all > cases. > > Fix generated by an LLM and sent by Josef Bacik in private. > > Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") > Cc: stable@vger.kernel.org > Signed-off-by: Josef Bacik > [ david: handle walk_pud_range() as well, clarify+simplify description, > adjust Fixes: ] > Signed-off-by: David Hildenbrand (Arm) > --- LGTM. Reviewed-by: Baolin Wang