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 0E267606A334 for ; Thu, 29 Oct 2026 20:37:31 +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=edeLt9zS Received: by kanga.kvack.org (Postfix) id 21DF26B05CC; Thu, 29 Oct 2026 16:37:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1F54A6B05CD; Thu, 29 Oct 2026 16:37:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 10BF36B05CE; Thu, 29 Oct 2026 16:37:30 -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 D08816B05CC for ; Thu, 29 Oct 2026 16:37:29 -0400 (EDT) Received: from smtpin09.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 534AA1A04C6 for ; Thu, 29 Oct 2026 20:37:29 +0000 (UTC) X-FDA: 85376824218.09.1DFCB01 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf06.hostedemail.com (Postfix) with ESMTP id 764E8180005 for ; Thu, 29 Oct 2026 20:37:27 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=edeLt9zS; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.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=1793306247; 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=234gD00LbP/Qk5j9zzqqy4STm6BqPfRIm1wBmbH9iNI=; b=ncweEh1cdRksdAEQ5Z/GqAS/4GZLuywQheV4Q69ZJsVXttU2iJjjUfAKs9qoasHKJPJZ9B rH5Arn36iOIfsY5Nrgbc8RzLYid/iRKbtHZtW7HVY/OhQbdlFyrgek1+TFwRhrSB/PYIV/ YuEDQM2hhTB1mM3pxbUgLD3nGYDt4W0= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=edeLt9zS; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.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=1793306247; b=nX6xbaZ1M6EPwJ9mV1ecOdWs7F1gdxIlbj2cseSFD/Dux2KI1rgQfKI2dtq+6yJyDdkyQ5 WydlK3jT9bHhCuKD3ukNQxjYdncV6cb7SmOSxq5ocLDig2xwA0TOXuIKivLyFVpqde9phr gIJq6zPI35W8zcLAyddIAfGs6GhY/W0= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C1D5F40C19; Thu, 29 Oct 2026 20:37:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75EB11F01816; Thu, 29 Oct 2026 20:37:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306246; bh=234gD00LbP/Qk5j9zzqqy4STm6BqPfRIm1wBmbH9iNI=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=edeLt9zS7/wt/9hnNB2ETmthM71RS43pg/tv3+Z3wip3JVZEmnW2zTc7BWQycloNy eiIxLdX2AHK+EIcGUho5VTaK6l3mGn1X0zTJHt1HL5v9rCLaz+t973Eeuf6OOZpwZq tzpjQ6ahggUdoqQsqXxoW/WHIIkOV547zpUK6vVcyeinMHiK9ttzsEiW87eUaXbGYB nnyFsqJECi9wQRjroEq+7Q5o/UeBBVUs5gLJ9jm2YeNOiFcd8EkUI59EM8WsoTFPNk 7toOVO78y+mRJVbYNeCeT6CcidBYrIzM+V4Q0SmKtYGNSa+6jYaaKFXHRob2/z8Y/b AxJkCxCEB1CXw== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:11 +0100 Subject: [PATCH v2 16/47] mm/khugepaged: fix PMD table lock leak 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-v2-16-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=2386; i=david@kernel.org; h=from:subject:message-id; bh=+GceeJLIEkYM45yBBgdZk6QP/zPFquzOdoh39+pg3EQ=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer23bNeP0wWvJS/X6pHY8L0u7YrDU4cqVVPcHeybd3 /DS7Vcsd0cpC4MYB4OsmCJLUPB9g5cv19VWu/Exw8xhZQIZwsDFKQATuV/CyHAx7CXX1+3Hj39y +TlL3JavOKg2cNKBuSrRv73q1jxe/4yf4a/Uz9D1Sdue6uUISi9b0CaQFe5uEnz6z6rLxwJNO+Y 3svEDAA== X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 764E8180005 X-Stat-Signature: ngrxht14hkuhmyr7m3nzzr595omez45s 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: 1793306247-901932 X-HE-Meta: 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 eXiNN+ol 4d6y8vhAV0EHmmrFgh8+S0IGOxQ+fbWKCoYTdoSwuUDiqQuFW4eZYVi9OwLlSaEZOdaKwdszTa7lDRFHKJHqNBTgRFf+QyR0IZFy3ZSdR/nFZGJUoqtPWL/R4+CxWaSJt2P2nV6o1085JO0oRFHZVcY9YLDBP0/AfpoDmkHp7utmRcWN98XsGuBdVeayslnpq5f02Ipgv5QMl6/CWv2fe4pgIFjDz/u3z33U4nDchakq8hOt9h/2yg9MSWqPQt6T7T8syUAbJeynATEi4bz2AMQO5Yh8PJeWp3IoV9bsLB8neKLV994dkyPKHIq64zqDQB6210oWJcFF1Om+iG/Xo+7SsxSMBshtB0o9yD5Cz7uU9dk7GLeusOQ+8O/Q9TSaJdp3BEQo2YkNBhJzmPzr2BBXAfr4aRoXAjykl3T9t+jed/K2OcqnnwZMbGvqCXExfLPL/AfyNdcBcwzJ+YM7AdzDUcB2AEGnRi+jIGI5R3Cd5Hpo= 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 For a private mapping with userfaultfd, try_collapse_pte_mapped_thp() takes the PMD table lock before it maps the page table for the second time. If that (pte_offset_map_rw_nolock) fails, because the page table vanished in the meantime due to concurrent page table reclaim, it leaves through the abort label, where the PMD table lock is unlocked if it differs from PTE table lock. In case the PMD table lock and the PTE table lock match, which is the case without CONFIG_SPLIT_PTE_PTLOCKS after pte_offset_map_rw_nolock() failed, we miss to unlock the PMD table. To fix it, forget the PTE table lock when we unmap+unlock the PTE table. 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: move the ptl = NULL handling; rewrite description, drop wrong comments ] Reviewed-by: Gregory Price (Meta) Tested-by: Gregory Price (Meta) Signed-off-by: David Hildenbrand (Arm) --- mm/khugepaged.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index f53c50507c83..04d9bb21ff52 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1904,7 +1904,7 @@ static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsign result = SCAN_FAIL; start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); - if (!start_pte) /* mmap_lock + page lock should prevent this */ + if (!start_pte) goto drop_folio; /* step 1: check all mapped PTEs are to the right huge page */ @@ -1935,6 +1935,7 @@ static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsign } pte_unmap_unlock(start_pte, ptl); + ptl = NULL; mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, haddr, haddr + HPAGE_PMD_SIZE); mmu_notifier_invalidate_range_start(&range); @@ -1952,7 +1953,7 @@ static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsign pml = pmd_lock(mm, pmd); start_pte = pte_offset_map_rw_nolock(mm, pmd, haddr, &pgt_pmd, &ptl); - if (!start_pte) /* mmap_lock + page lock should prevent this */ + if (!start_pte) goto abort; if (!pml) spin_lock(ptl); -- 2.43.0