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 1D1B960A2607 for ; Thu, 29 Oct 2026 20:33:54 +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=BtblEQni Received: by kanga.kvack.org (Postfix) id 23D766B05B1; Thu, 29 Oct 2026 16:33:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 214AC6B05B3; Thu, 29 Oct 2026 16:33:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 104B06B05B5; Thu, 29 Oct 2026 16:33:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D04146B05B1 for ; Thu, 29 Oct 2026 16:33:47 -0400 (EDT) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 430FAA0502 for ; Thu, 29 Oct 2026 20:33:47 +0000 (UTC) X-FDA: 85376814894.28.9AE2099 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf11.hostedemail.com (Postfix) with ESMTP id 874DB40006 for ; Thu, 29 Oct 2026 20:33:45 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=BtblEQni; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1793306025; 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=Hl8Hja7261+PqX6A1yngTbcTCPox77BGspRqPrmbmIw=; b=yx5SGRnBbMg8KsI6qsUbVnsaBq/g6FjIKgnrsJrwi5WWVvYZdFQ62nqAoUGm9zrMOetfmn MLw9B2T7tbvMBONUEtX0m0BM3+kT7EHouXimER7t2ARAzHlrNZycJ/NeMGIowi4wD+FVwY ordJp8ZIKgYlezSn0jylcKBcPR6fx04= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=BtblEQni; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793306025; b=a57KK5tKrBrPdowd/ReeZfLcJNnG3+YcjSZvZ/laXGa8klELadrALa1gz+vkqQkUoaJxU1 J8nd7En05ed7tDjte63rfskNw1XPWINwxnllEyP4NrlGENde2+ZJkoo5AOmi19FUPsNzDx XIlggcAQyvT11kDNQ3KH8I6wHBI+lfE= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id E8418600DA; Thu, 29 Oct 2026 20:33:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6E1B1F031E2; Thu, 29 Oct 2026 20:33:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306024; bh=Hl8Hja7261+PqX6A1yngTbcTCPox77BGspRqPrmbmIw=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=BtblEQni/tV7KmG4ZsM9UPfe8T47hGMbbRdFSbdDMyagtA6eYkZbhluhI9z5BurdL 1e78U6Dqg2OUvWYcFR0R5N87ly5LSuFRTWMfolODfDF1YuUhHuMAr0b1iHsc7D3Zok WWXgLFaB/7lS8DNFBPkUEV5jhF93hksYscJQ72sXQp+mQe59teJ8lUli9p5tFfB4A9 Wz6e9K2qIY/jLVAnShYPw0I9kE8fFZ2d73v1Bo2z6zzKA/PIuyGuoriHgYP9CxUnrd fa/lB7eBUKMmE00K0RofgBKFQ5hGuNr17dEBDn3gMz8NHlng/llC5yjiUWyFxZr+iQ 1NGfRY7z8HfBQ== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:32:56 +0100 Subject: [PATCH v2 01/47] 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: <20261029-fixes_core-v2-1-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> In-Reply-To: <20261029-fixes_core-v2-0-a64ce7f83abb@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, Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2764; i=david@kernel.org; h=from:subject:message-id; bh=kEXlYNiQWeqMYPtO5Vb4nXU0nymzCVHXtW6ux1YnkxM=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer2256v+r64KNwb7oXRXbchL8DsTsVdVJFHuRImHuO 1Xm9q1ZHaUsDGIcDLJiiixBwfcNXr5cV1vtxscMM4eVCWQIAxenAEzESYvhD9/mT2dFj7Wqffct nXRd8fk7gdkPyxdo7bD4kys6+eDSXysZ/lc7b9U16thV9e2thKX+9d0xK38eTp3Zs4hT2P0qxyT NN9wA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Queue-Id: 874DB40006 X-Stat-Signature: oo7m4x3aheu3qjrw7q914zy18opwadj5 X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-18.8 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: 1793306025-995981 X-HE-Meta: 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 iMuOssXl 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 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. [ david: handle walk_pud_range() as well, clarify+simplify description, adjust Fixes: ] Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik Reviewed-by: Rik van Riel Reviewed-by: Qi Zheng Reviewed-by: Dev Jain Reviewed-by: Lorenzo Stoakes (ARM) Reviewed-by: Kairui Song Tested-by: Muhammad Usama Anjum Reviewed-by: Harry Yoo (Meta) Reviewed-by: Barry Song Reviewed-by: Baolin Wang Reviewed-by: Pedro Falcato Reviewed-by: Kiryl Shutsemau (Meta) 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 9959ca158ce8..6a1af9b92349 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