From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3464E60A2639 for ; Thu, 29 Oct 2026 20:36:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=1Ul1ub7J; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Wn33W2jS DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=q5vK/qK4XuBQrL53cs9TeuLxUrSX2eJpWdLNS5EZvqY=; b=1Ul1ub7JAjprg7 WQkJ0jVQrOvVrvkqaPDjPyoiingfndfb3wxPeVCSCWv3CfWFv72gOgvkNAK5r8f0svNfv7H6Dnlb9 vRcaV4TWW3RIiUXam3aVxj1LBbae6Vhvm8mCwfwBLitK/950Phdza5wpDanO2obLyHw8fufm6Rf2i 7xm3wnLfKnUgQQ1b01e18DPOR2f9Hs8o2ew4TRi6Psw+Vv6r7gIZXfBrCtDiiSa3yR2txUdOEWtnK fb7rjF3mdP0MvdOJ/u3vUNl1RIaonItmdajpl3znoa9P6SERXFkElBt/aOlLf+ZKrhVh/+P2EqMhU ZAVJSBE2XymjcRSFr7vA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMWrb-0000000AKur-3kkB; Thu, 29 Oct 2026 20:36:43 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMWra-0000000AKuh-3O5Z for kexec@lists.infradead.org; Thu, 29 Oct 2026 20:36:42 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3E89240F48; Thu, 29 Oct 2026 20:36:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B39EF1F01816; Thu, 29 Oct 2026 20:36:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306202; bh=q5vK/qK4XuBQrL53cs9TeuLxUrSX2eJpWdLNS5EZvqY=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=Wn33W2jSO7FMd6s0f6J+WahGrG50HQ170ETyv6hs47qSO1TwExsP9mS9I9/sBR3+c 7wsvODaM9WxAO5Rc5MJD34QTdFNd4D08AlxQyrVme7gS4+H0uLmPkOVIJZg7RTVfdc zaLgXKXLjTgdZKdtfmg0AFBGu9Ssc9s+ntFiFxRAjCvlss1/LcmLsBYqtdrqVGlRG0 9CDMyd4sYfaUFqKRB9NscT9OhnDRrKnXImU+vH5BiOtbyQW/e/5qy85Fn5d/9xx7cr Su1TurTVFKrvkJSSNlOjYBJx5bpNzRnX2gPRMqdkL8WXnfFrlviI2cmvyyjoLIzbjy 7x2DRkHzJkQnw== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:08 +0100 Subject: [PATCH v2 13/47] mm/huge_memory: fix truncate racing with PMD zapping X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261029-fixes_core-v2-13-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, Chris Mason , stable@vger.kernel.org, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2058; i=david@kernel.org; h=from:subject:message-id; bh=whzXA4Qm4HXSA1pqm4tcjWrVcDozZ04CivHfstsAKVQ=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer221D+SO8q1Sly3O/b/h+7nDEu/kw7iWNp/nM7Vet HgP39H4jlIWBjEOBlkxRZag4PsGL1+uq61242OGmcPKBDKEgYtTAG6yEMM/UwX358mXle/zSWT1 C8a7zAkNVfL6do+z7XPyZJFLRnKKDL+YK/rkNSuXzGoxr93d/TuuL1y5+PQNd8e8cyxz3n6uMeQ BAA== X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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 ] 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 2b31a425c7a3..1d65c4f576f9 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