From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793439818; b=iOUNAXvEeUbLX+ouZk29c1CQi4ViRwWOUNmoibR6IK7aAZm+A2A38rARxKtcacvmEBeP JUShFy+osZC0VNKOYF1/l0AOUVqRjzIRvz7+b9hQaLP/F+203WmEdjt7ncs8Got/8b3Vq PyjuvssPrWdiSk06AkP1vJdtQCN0bQ0Xv9XCFNvt1OwSfM8kex0Agaeibankr2uPKxou1 2iOV7N3D+a8fSnnD4VfulQMBeu2CpQodSOhstjMHkBWkv/D3q+SQjFqsNF6g6GDXkpZtI ORQ5mMw7KrsD9KkGEG0v+rmMQnJO9o7jj0y9Did2GZKSlCFKYJe+eCaqhBDiG6eXGow== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793439818; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=75zyuTtsuafOzEahVl+WZW7s8/QVADxO/YkiuCeEnRo=; b=2/pcWoAK7pTJ+vhmviEaxYfVZwcBMqWe8gYnv8zCTF2SIS6Pl8aJsDxagPGz3mK/YGF9 dxnCkOS8RKQ4su1Uk9FLKPr8JUh74w/FwRYYUR7+h0ToqBMtHMFDJNzAmCOSQEEXIUmKv MjJ560I8+UsPuzmuBMLGgYurv6aJ8ClIMhNb1WI3OR45D7FDBWOJk70fKrKmyaDXG2g1D pW0SYaPkuwLnmVyj0sLjVv7X6/GtIOAf0DOGtHdOvTAzKEMD8Qa/SdH/VS5Xe2ME6IZJD YMXVsPnIaYh43/CsdVfefvCRv10SNQRIKx4mz5SEektQdTDeLO0qoPkpIS9Gr/avGIQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="gcS0/DUx"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5B150606A31D; Sat, 31 Oct 2026 09:43:38 +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=gcS0/DUx Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8303F1F0093A; Sat, 31 Oct 2026 09:43:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793439817; bh=75zyuTtsuafOzEahVl+WZW7s8/QVADxO/YkiuCeEnRo=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=gcS0/DUxOyrED5eDMwrEZauk5YChzRD/FtWcSvQxODQn2n1L5cR+0qiSKRFzIBJLJ rFW7DasU5sYC/6T6La5izc16PE0mNI4Rmq7lrcAoDy/3JSML3NIwB2Dy4LwGNEkDzk SdCGyPFFzDm+aklv+bE5cesAY0SEdFelz+QT39Tz91CacOq/vM0xsOKUwUYWUrjM+Q rPAdwWRYW+lOcIU/oOjW4RbqF6vJKaHKvYVsDcVjBWiOHyd3KKoUDsIsEbWEI/D7UH g9meyzaJhxk6j3y+CO+n4QNctXXT5KX/JCqJD9f+HW+WtwxJCB3nR1DFqH5enrefnD SX5I+DKM4l9vA== From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:39:42 +0100 Subject: [PATCH v3 13/47] mm/huge_memory: fix truncate racing with PMD zapping X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261031-fixes_core-v3-13-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> In-Reply-To: <20261031-fixes_core-v3-0-d6437171ecc3@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, Chris Mason , 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=2170; i=david@kernel.org; h=from:subject:message-id; bh=1pZO1fewpEQg6xUjsBTP9l8Sg2iOXw60MZ7AwrYjmYc=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebk/TS8wsNG5f1ynrc6d0j+aVF32aYYfOzW1q9LWMM mKWe3q+o5SFQYyDQVZMkSUo+L7By5fraqvd+Jhh5rAygQxh4OIUgIk8rmX4wxHw3HS79LrHHm83 7faz1PnZltr5tf2xrC3z5ppta08Jr2P4xXyOYYqJ9velqxW93AXPKWv0JXPH/myoOvmtu/OBy7I CdgA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A From: Chris Mason zap_huge_pmd_folio() removes the rmap before calling folio_mark_dirty(). If this was the last mapping, truncation can skip unmapping the folio and proceed without waiting for the PMD lock, racing with dirtying. ifs_set_range_dirty() can oops if MADV_DONTNEED races with ftruncate() on XFS, when we get the folio set dirty after it was found to not be mapped anymore. Move folio_mark_dirty() and folio_mark_accessed() before rmap removal, matching the PTE zap path. This keeps the folio mapped while updating its state, so truncation must wait for the page table lock. Fix generated by an LLM and sent by Chris Mason in private. Fixes: fe6cf984939d ("mm/huge_memory: transfer the pmd dirty bit to the folio on zap") Cc: stable@vger.kernel.org Signed-off-by: Chris Mason [ david: simplify comment and description ] Reviewed-by: Gregory Price (Meta) Tested-by: Muhammad Usama Anjum Signed-off-by: David Hildenbrand (Arm) --- mm/huge_memory.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2b31a425c7a32..1d65c4f576f9c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2495,10 +2495,6 @@ static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma, { const bool is_device_private = folio_is_device_private(folio); - /* Present and device private folios are rmappable. */ - if (is_present || is_device_private) - folio_remove_rmap_pmd(folio, &folio->page, vma); - if (folio_test_anon(folio)) { add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); } else { @@ -2512,6 +2508,13 @@ static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma, folio_mark_accessed(folio); } + /* + * Present and device private folios are rmappable. Remove the + * rmap after transferring young+dirty to the folio. + */ + if (is_present || is_device_private) + folio_remove_rmap_pmd(folio, &folio->page, vma); + /* Device private folios are pinned. */ if (is_device_private) folio_put(folio); -- 2.43.0