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=1794272700; b=e1KBDgfHbJ7peIwpTomyyVopCkqkzeBXLV6A+D5UKBlgMlTQxfuC19DGRYTYldTWLzdi v0niw+lS2s01w45y0y+0NVrFqBc5MnnLLu9ovSg6GyXt0HvIsbB+3eXeZQekLVctgSMp+ YqQXY/o4e6alkGr8AvvbEhwCEPWwnMAPBOjgPNjSQlJomyHlLIFXo7qALIZkWADOn0BUr Hm5vosNs5c2H9+CWEQIuS3SXY4azB9QzYPdiWlMUTPkgb6owkC95/Yxdug0SQfv/S03hf vmSYzyxfzi65ukMioR5sGhYNX0cv/wYXc/DBhbW6MmqYedqNalneIuSDFKvEXwB+X6w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794272700; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=PJoem8rsTZPVaH1EMPkhycYJe/SXScaAJGrvoswRZho=; b=mGUgneqPetdYcTyI9xA22bUVvhD0UT4V/lenvHv5Tk6GeJ/VmMmT3+62RBVHnCDoeM15 smHbHWm8zzYt+rkNNcKvmHt1I0uj12IJGfWiifa442VDd7htKcrGHmOMGm0OT01izOmqX 670q/bXhfvmKHTtPidC8hVqeC+eFK3MSpVcSDunESpMDieC+YCtL/5/TZVNYuuNO+Fwp/ 76cqMJ7POQOWfCgsatz69N5zyKXXfA+ULWJHmTGrxd/XbZ+jXFMisdf6vky3vAmzVnp4z qNGcUN9CwMZpBmnA9j+5mFraR06VPQkeMu99x/Rd3q+FdMGU0gdVV0W0zApnqR3nkNQ== 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=mmhk1cVX; 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 BD280606A321 for ; Tue, 10 Nov 2026 01:04:59 +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=mmhk1cVX Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE95D1F0089F; Tue, 10 Nov 2026 01:04:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794272699; bh=PJoem8rsTZPVaH1EMPkhycYJe/SXScaAJGrvoswRZho=; h=From:To:Cc:Subject:Date; b=mmhk1cVXuxTNzhO51qWgzABdjmWPA0FXcgXnC+7ibCXsA9Mjrps0Q36EhaAenXq74 BdyGH6uqu9/f/6qmQPjYt2kkvWiyNJ7D1AqGQjPYK4qxEuW2KOROUC2sbR8U+iy3e4 HDp5Yqi4aQw2p91s02qpSCTAMxW9Lv2QaRC79RjMrRYB5j5F4xachBp24iDwIf5woN 9zTLHQMwOcz1+rta3sCI8+mav8PxhDni0O0lHKuVlrUjU9GI3hUuWnASrTUGLu4PGc D9hl0vBw8uIfGmSB1svpAl9hadBkLE7pM3jH3Sh1aV8booRTp/i4oFv1UKmiW79l+N crblxMo4/oxqw== 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 6.18-stable tree Date: Mon, 9 Nov 2026 20:04:57 -0500 Message-ID: <20261109200457-failed-6.18-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 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x e6a07d29b0a60f3a4cfe77fe34eeb4b3fb38d6c4 # git commit -s git send-email --to '' --in-reply-to '20261109200457-failed-6.18-e6a07d29b0a6@kernel.org' --subject-prefix 'PATCH 6.18.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