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 03ADB60A2619 for ; Thu, 29 Oct 2026 20:37:16 +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=dnPvAICq Received: by kanga.kvack.org (Postfix) id 1A8D76B05CA; Thu, 29 Oct 2026 16:37:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 180FD6B05CB; Thu, 29 Oct 2026 16:37:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 01C696B05CC; Thu, 29 Oct 2026 16:37:14 -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 D6A236B05CA for ; Thu, 29 Oct 2026 16:37:14 -0400 (EDT) Received: from smtpin25.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 643874050D for ; Thu, 29 Oct 2026 20:37:14 +0000 (UTC) X-FDA: 85376823588.25.AD0CFCA Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf13.hostedemail.com (Postfix) with ESMTP id 93FDA2000B for ; Thu, 29 Oct 2026 20:37:12 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=dnPvAICq; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.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=1793306232; 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=tNxobpWlUXNjZHphvvtOgvNQKSqjJiSYupG+wXJMVoE=; b=Xl8mjb2pE/+E5IopxampZV3ezlr4o0kZjz8DObnLtEJOqESjGaCY8u0E9MjfxOIaf4tRNP eGMDuLzDD6WA9UemzAvnR2aM+D6tOuWPhcHvNUVKR0XZVDb0h8Ownljsc5uw7NevFyhc2I etq9J6Ryp5U6WhmRIjEi0yRCwMosDaE= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=dnPvAICq; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.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=1793306232; b=uK5Vptwr5DhN02bqy373rC7JFQxSqhDTgWRfPyIYJA8V4cuw2q9LmjKCeJACXfPWjfOj0f cIK85n1oBRPiEt9jQB8UVBf+tVT5QHSlwWNVIB5lC42VeWwuJv+NcRRTWhkGGR5ipdLdsi UYvLf+dFUAcVMI3cNzA+oLvHdcOcodc= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 3597B6020F; Thu, 29 Oct 2026 20:37:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 800E91F01816; Thu, 29 Oct 2026 20:36:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306231; bh=tNxobpWlUXNjZHphvvtOgvNQKSqjJiSYupG+wXJMVoE=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=dnPvAICqs5R8ijwgTMhLfxbmgHzO9ja4TQwnVekFvzI4/Y7pZ5RiY6O6tVJsThGVV 0+fRYRkM1yM1n6cFK+iCf3ZqyzqyhwSxWilIYYeoHZzbo9N29g9v86q9A13gDR/zAg 8DtvbNaMzwDgGrBUQB5UExtEwWaK0Dn9sbaFts/LVGL/R1SW2YpAU0BrON2RUO4yYy cu/4SgzAJ0FHs5/Ri+ZxG/yPhlMK/kh2s08tuIv4giMR88cv5B14Ge4CBnqQ8xk6oa 1CwTQSEOwzHx7AbzR0KZQSktdzwEh8USZEjLO2tgQvbt5Dkn/jHz3doUQYIsiZKPxC 3UQpIdOeycdlw== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:10 +0100 Subject: [PATCH v2 15/47] mm/khugepaged: always recheck the pmd in try_collapse_pte_mapped_thp() X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261029-fixes_core-v2-15-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, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1608; i=david@kernel.org; h=from:subject:message-id; bh=KkwG8uxQMmQsjX2diZyIiRGRbeEH7cv/itYGtmQ0sPg=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer23LVcs0DZ+Vey1b3SqpnrEvsuh3u9sunSOS0y9ke OvO3DSho5SFQYyDQVZMkSUo+L7By5fraqvd+Jhh5rAygQxh4OIUgIl0pTD8Zglw/6lYZenzR8hk r8l90wVv172VFuh9dvaBH8e5W5P3izP8DzWJnPD4TI3eYUNe26sd69i/56mUL3HNdaxgFvxTHXi AAQA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Queue-Id: 93FDA2000B X-Stat-Signature: 8sdidwnw48pkdp9xjaty59u88rhydaf5 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-Rspamd-Server: rspam09 X-HE-Tag: 1793306232-328444 X-HE-Meta: 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 JE1L/7OG TbWkWRspvPevHllFjAKXgRiU0EkjnkkOW4Vpd1Xq5JGnDo7Qzszg1yWbyo4x6cfGm3fep8pQP2Y9IThthzpHgwfAyhXxlkvBtLADh45+0h6VWx2HEx4yQ/GzsmS4poZ1biPy4d7KxocxDVMNYWTYqu5f9oucGcLAjF/0FSd1+U05tCw7NroGRDG4kURY1D8y1PQGMbchz3WPzjRWYIAZyJBet0Zy3xNCXnzLF21r3p5QRh0vEz2dgEgoQ42wybty/4GrDPl9jKzxYefsxAGPL6qTHA8fxUR2vzDaaJrDnSslOb+cvFry5vQcP2FYm6OT6jTFyr0xL6lqDxkU9u+W++4qrlNoeGyVeTAHTO8gUlAv6clLiCqDuYfeWt0bnsAmYCgOuFsqwTaIhIZqk3EYbNuc+bR0mGJ8tFHCnOPScTdh7pRd9NkEGAn79hMv5tVdXwLt9N8gVG1qI8GYjia94S3XHuJvzO/kQEwyc 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 try_collapse_pte_mapped_thp() drops the PTE lock after it has cleared the page table, and takes the PMD lock and the PTE lock to remove it. In between, MADV_DONTNEED with CONFIG_PT_RECLAIM can reclaim the page table. The pmd_same() check is supposed to handle this, but it is only done with CONFIG_SPLIT_PTE_PTLOCKS. Fix it by performing the check unconditionally. Fix generated by an LLM and sent by Josef Bacik in private. Fixes: 6375e95f381e ("mm: pgtable: reclaim empty PTE page in madvise(MADV_DONTNEED)") Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik [ david: adjust description ] Reviewed-by: Gregory Price (Meta) Tested-by: Gregory Price (Meta) Signed-off-by: David Hildenbrand (Arm) --- mm/khugepaged.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 4b71d010b2af..f53c50507c83 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2013,12 +2013,11 @@ static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsign /* step 4: remove empty page table */ if (!pml) { pml = pmd_lock(mm, pmd); - if (ptl != pml) { + if (ptl != pml) spin_lock_nested(ptl, SINGLE_DEPTH_NESTING); - if (unlikely(!pmd_same(pgt_pmd, pmdp_get_lockless(pmd)))) { - flush_tlb_mm(mm); - goto unlock; - } + if (unlikely(!pmd_same(pgt_pmd, pmdp_get_lockless(pmd)))) { + flush_tlb_mm(mm); + goto unlock; } } pgt_pmd = pmdp_collapse_flush(vma, haddr, pmd); -- 2.43.0