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 D53A9606A31E for ; Mon, 26 Oct 2026 23:18:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=N0Io6SX8 Received: by kanga.kvack.org (Postfix) id CFCC16B05B4; Mon, 26 Oct 2026 19:18:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CACF06B05B6; Mon, 26 Oct 2026 19:18:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B9B9D6B05B7; Mon, 26 Oct 2026 19:18:17 -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 88F076B05B4 for ; Mon, 26 Oct 2026 19:18:17 -0400 (EDT) Received: from smtpin07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 19A5B408E6 for ; Mon, 26 Oct 2026 23:18:17 +0000 (UTC) X-FDA: 85366343034.07.C163A97 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf28.hostedemail.com (Postfix) with ESMTP id 42EB0C0002 for ; Mon, 26 Oct 2026 23:18:15 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=N0Io6SX8; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793056695; 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=NUBP2xRnXTWkvkzljjau88QTTUDveY6Hz9RAZJBGdTA=; b=KE1Gs1NDxN152S3zKZJMiEZu7cwi6UI6WUhHL+JcJK5XLcnEWcpthGc4vW7VvEct1w2xsE /uhJNQUzS2hYjzszx+GIHymrUyAjadqlM/4ogWuGZ2Nlp53VYSNDb/CMj+piBNTR0RihkV MCmzrKKp8EzWdzTSGVThpzmxpm0M9S4= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=N0Io6SX8; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793056695; b=3T8eAaf/PSiJ85xvbNfndyJ12JYEqQmoFwVeB5I0aKbnvLbW9RVWDuNvVuHZCZaXNc2bvH gLN/a/SYt+kZmy5aLJmk0fbrJqV8ANANyCPJJaGyQfPkQHgl5WyJbtLO2ephq5TCr8ivJy CdIm7T75FlDfOdA8TIzbEk4IsSUA+po= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 7390C4095A; Mon, 26 Oct 2026 23:18:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4034A1F01828; Mon, 26 Oct 2026 23:18:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793056694; bh=NUBP2xRnXTWkvkzljjau88QTTUDveY6Hz9RAZJBGdTA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=N0Io6SX8cBzzTDOb7cpNCY6FTZU/h+KZanqCjpiuERrlKcwqPUmds2XacPzDJEdk4 PYZRLj+AoUQoLE6z+36JUW94y4Bp88f3cJod9gQlvbGbNdqQlAhw18OBaLdHFRSS/q AmNfMdre4JdR5YYAE/k4Rm8QdRbDk1YvBQqj3ljM08SjJ/W5VLEH6Of+WTIkuE7YcM aAnkYNndmFBxnm4FtuLiESvFhlCip+lgP5vzefuhDl3xbxXkMESzxxRjpavTYuronn umBEwX+v+06COBgPtWP50OU+jEh3Dd9mcFm9RqijNKNh6N3UEEBuJYsTMOvJ5UqGVT OMLDSeCDpWsOA== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 00:17:21 +0100 Subject: [PATCH 01/46] mm/mglru: don't use stack pointers when walking PUD and PMD tables X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261027-fixes_core-v1-1-6f74bec9a5bb@kernel.org> References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> In-Reply-To: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "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, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2223; i=david@kernel.org; h=from:subject:message-id; bh=35PvaXKWWy0wg30tuDie4oWbed0+71n+0SGauq9bLs4=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu35+kxCFy6tE/r17VSuMD+w0ueUdwpk73e7hsKZNdZ IP9v4zojlIWBjEOBlkxRZag4PsGL1+uq61242OGmcPKBDKEgYtTACZyJ5nhD5c65/fu+Q1lbuVX lQuzF8Wx5tbVeTgvc1zKKt+8aWesCiPDfdkuFpbL603lW0oeZNmsVj9stXrGL6G3u6s954V9rgn hAwA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 42EB0C0002 X-Stat-Signature: mcow6ok456qu85tf1juiouufra5u5fdj X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793056695-935708 X-HE-Meta: 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 l44ePkOf euovkEx//86UeXxR99hBU8BsFes7/HxtKcMEU7BhFp3g+l8uVMXTcaoXcYnkyGOekLJArmLUwhMMKGNFCnIK5DLTDQey7fJ8CKEP10xYoB63MJwYTLf8oWznaDyq3rdBZLHdso1jakaa0Bw2JP8teJ6Zape88bl0ftiW3oohK6VdCQ90VrJjtyvQnfpN6sAGoLcYYVx2Ymq/kdPIHxdxljbJi7sIS43CtMGnnEKytFw/6nt/qIyvmf3bAZposaTc6ccW5IDyYCaX0nuh6q5udLdJMT9O3Zo18esoeAA4V/ANidB5eEGah6lJIGMCbNqImCj1XdLXKY4+Oaly9gOtJykRK/Ecx8otKZcIjGHImM9ST1+sjzxMhHwDhmlBSvRIPxCP2 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 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) --- mm/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 9959ca158ce83..6a1af9b92349f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3911,7 +3911,7 @@ static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end, walk->mm_stats[MM_NONLEAF_FOUND]++; - if (!walk_pte_range(&val, addr, next, args)) + if (!walk_pte_range(pmd + i, addr, next, args)) continue; walk->mm_stats[MM_NONLEAF_ADDED]++; @@ -3947,7 +3947,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end, if (!pud_present(val) || WARN_ON_ONCE(pud_leaf(val))) continue; - walk_pmd_range(&val, addr, next, args); + walk_pmd_range(pud + i, addr, next, args); if (need_resched() || walk->batched >= MAX_LRU_BATCH) { end = (addr | ~PUD_MASK) + 1; -- 2.43.0