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=1794273206; b=KHZ4/JGR43bihr76BRxB/y8s+6lfJB6BXqmALKQ7ymbV7S+7gXOTjUmBeUzn6mneRTTT cVurXpdg7xXZecrHgzUm2UMVObnCHnnUR8p/7qu0qL/lMS0TEQ6dhLNEpc1LVv+z0mKsK p9CYnrws7epQr4ddamcEJXF45gL+GgjbMLOJ5DkmDV6tKPkb8esntJutMKh6ep3sUsl1g LM04Ve6XWiDkaVcBS1thNT6DLDAQaMvOuGbsEexZ3NA4DBpuYRUReHL1OoZbZXcI/pMPX z9LTQZB+bNNzlfmkNBtJFFtmsKs4DE/B4Tk45Rpw4mKeUgmZ5bUPlMKQ6rRiYCxkhQQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794273206; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=43/tFBgEF0BSlo4C3zOQYURBaxwj2NGmcAhTktQUmEw=; b=GjwYbdXp8dBY9PSIUGCzfMj7h0ndGRqlOQLYnW6GqtpDIzGjm3Ag+cZR2SwokNhD3KH4 +JzgcQ3MAuSTeFpxIfq7KM6psC7WmctaFXd40zidEp2dmImHkikZ0rlLjjATmlq0YZQex v5+tYI/jrN0cxBPBLNMHctN93cOeHkDzULnp59/k2pCPnTUO9rUabDbN7mI2EC7v2NJEt DWBO3TnMdMqSD7ALlgZ1WA1Qfj+ji7tkc5pBvhkoP8eNuRSqq+0pYEUU6iffWgZA4hUgl UJftlyUucedGMm6Zm6ssdeFO/9Y0AFn7lvm2ExupUF79RDPlMYyc3XPda5tRlZjpJRg== 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=i58KaxPj; 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 1C2EE606A31C for ; Tue, 10 Nov 2026 01:13:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=i58KaxPj Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F6D01F0089F; Tue, 10 Nov 2026 01:13:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794273206; bh=43/tFBgEF0BSlo4C3zOQYURBaxwj2NGmcAhTktQUmEw=; h=From:To:Cc:Subject:Date; b=i58KaxPjGDr5xwnZJEtl6PvFkOUf20TtLvQFI9w4C3n+vtUneQySIJdv+9hc6smIt Q/lOCzvUZqbRtCifBN8yF00pW1NCoWm1OFKmHjAVsIhDSiYADnUHKYrC7POtco8iEa MzBcaLlrtZBURdHIluzCUSTuEumASGffBqMA2gEtu/TzZkhaR9KuBSzCsxCnoFYEDE zyphbwNcGmFYZWRRpbb08Gl7mtbd1ZJKEz2PY6qltsvNwDl3qipL53qs2K6ZGX1ZCb v6rUkXE3gPHTuttX6FHW4ILBPzHp4QhWzLL2CI9NhH9m0So9sky7bzRdVAvc3hmRi3 frlKPJK6SKofA== From: Sasha Levin To: mason@kernel.org, gourry@gourry.net, usama.anjum@arm.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, david@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] mm/huge_memory: fix truncate racing with PMD zapping" failed to apply to 6.6-stable tree Date: Mon, 9 Nov 2026 20:13:24 -0500 Message-ID: <20261109201323-failed-6.6-e6a07d29b0a6@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@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: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x e6a07d29b0a60f3a4cfe77fe34eeb4b3fb38d6c4 # git commit -s git send-email --to '' --in-reply-to '20261109201323-failed-6.6-e6a07d29b0a6@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From e6a07d29b0a60f3a4cfe77fe34eeb4b3fb38d6c4 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Sat, 31 Oct 2026 10:39:42 +0100 Subject: [PATCH] mm/huge_memory: fix truncate racing with PMD zapping 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 Link: https://patch.msgid.link/20261031-fixes_core-v3-13-d6437171ecc3@kernel.org Reviewed-by: Zi Yan Reviewed-by: Baolin Wang 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 283c4bc8b927c..ce52962db16b9 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); -- 2.53.0