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=1794420919; b=VzsmssmN2KQGCeUdUQtufNSm0tb33GIofRobybgVOzgoYpWUaeF+OJJLwvVEcqZTXVYJ IV2LwaBaLoqaPBShbuFwW38QA5Ml3/V8udexzlDcmzTOcVC7UlJOaohMaY0rsvZfIN+3O CqGuxw4AnUN3ZHepk5wORTgShjs+YMgEfd95R7D7O6ZFCEeeYQwxJCTCIK//bUII4QzuA TAaabO3qpAmkL3KDdHgiZKgRb/Qcxb6cQrwIwnZcq2F2SB+dnE2V81kR2rh3t+vdB0/sp sAayeI8Ph+vnA5GJiuKw3P+jzv8r2F4oG8fKUXE0P7fip8YZSHsvN8o6WVJtd1H47cQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794420919; 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=h/gMKka0KRVoDYIjz1ajHMHaZowebVJOe2Ih0vRtI6w=; b=abUMFIQzW1wGAtakasGIUVvs5YquvbrvEjCuquQCyyLqcSPM7CRSLY4MnPfDItQGqsf2 8i+BYfq+M7T8FPtRkDJvHHD1udv3YmItff5KTcWjotqz4Q11n88CBJDMJ/OX5CLi6BPT+ Ys1bQnAA+vr7WueARjtXvBCBSV486Tw54j88N1Cgt52cG7cjmciMdb/D5+opIPSVMUKI1 vCtrU3Rzq9rhVfsLMHBwXtqBbpa+3bslo4TGtHAsQVJP5069VtTNrIY/yWGspjVKUwtGp YRLyCMR5mY8U1UuucXV1q/SvGFT96yegBFxpSLt7E1UaI174QXePDAFnmMXO8/176Bg== 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="G3G/Avwr"; 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 67DF2606A88D; Wed, 11 Nov 2026 18:15:19 +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=G3G/Avwr Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14AEC1F00A05; Wed, 11 Nov 2026 18:15:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794420919; bh=h/gMKka0KRVoDYIjz1ajHMHaZowebVJOe2Ih0vRtI6w=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=G3G/AvwrGxMCrgciaaymdYokDEwWVMqcW7sQoSgNfmLG73ObWU4/CgPD83q/GF3HC l6OrGPBF3VkAfcGm48h26cMxgB7gl+iWHYpL9jLI89e5MkWICAxZ9cXNa5RVf2AuDd NkZMzfZtPNsjZ6C8UMlihXtXGK53CtGfw8s5FG19kEVcWjA6DBL+cbnKSq6cCfxLH6 H/tt27z5bi9yoy5sBEc4ixkK0plFfI3O6qSdFra3ueHxclDVFiCV6jAOKMIFxwQlzg 0uQHib+dInkNx5CR9sn3rPUgt8skTptKHSpECdXZOq/WGl6wPw96Z1SlCiYG6AtzPM 32lhC+r1+zjBw== From: "Lorenzo Stoakes (ARM)" Date: Wed, 11 Nov 2026 18:13:21 +0000 Subject: [PATCH 07/13] mm/migrate_device: look up fault folio after a split X-Mailing-List: linux-kernel@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: <20261111-mason-migrate-et-al-fixes-v1-7-3d2454362e8d@kernel.org> References: <20261111-mason-migrate-et-al-fixes-v1-0-3d2454362e8d@kernel.org> In-Reply-To: <20261111-mason-migrate-et-al-fixes-v1-0-3d2454362e8d@kernel.org> To: David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , David Rientjes , Shakeel Butt , Andrew Morton , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Nhat Pham , Johannes Weiner , Zi Yan , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Usama Arif , Kairui Song , Balbir Singh , =?utf-8?q?J=C3=A9r=C3=B4me_Glisse?= , Kiryl Shutsemau , Yu-cheng Yu , Dave Hansen , Dennis Zhou , Tejun Heo , Christoph Lameter , Peng Fan , Josef Bacik , Chris Mason Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Borislav Petkov (AMD)" , Mark Brown , "Dennis Zhou (Facebook)" , Rick Edgecombe , "Lorenzo Stoakes (ARM)" , Josef Bacik , stable@vger.kernel.org X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1644; i=ljs@kernel.org; h=from:subject:message-id; bh=4y13Zn4Hv1aBFdu53Ug8OJJPI5ryvtg3+l0TbgSLV/c=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLK+bMiuPGJq8Kpaq2TdZ+lvpce7bHgDLux73dg61z/n8 1/R4EVTO0pZGMS4GGTFFFmefxHfHyQSNq/zgr8bzBxWJpAhDFycAjAR/VMM/5TmGzLqzJ/p75i+ 4/qipbOme54KaW6avPTDk0kZpg8Kz5QwMvQsmeGpL6hfW2uxSua96fsk/f/LAxdMWOl7fOvHrQ/ 2K7AAAA== X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 From: Josef Bacik migrate_vma_collect_pmd() looks up the folio of migrate->fault_page once, when it is entered, at which point the folio is locked. The fault folio is assumed not to change after this, however if migrate_vma_split_folio() splits a PTE-mapped large folio which contains the fault page, the fault page ends up in a different folio. Resolve the issue by looking up fault_folio again after each restart of the walk. Fixes: 022a12deda53 ("mm/migrate_device: handle partially mapped folios during collection") Cc: Signed-off-by: Josef Bacik [ ljs: pared down commit message ] Signed-off-by: Lorenzo Stoakes (ARM) --- mm/migrate_device.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/migrate_device.c b/mm/migrate_device.c index ae795fdf36f4..45e571dbfb4c 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -233,11 +233,14 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, struct mm_struct *mm = vma->vm_mm; unsigned long addr = start, unmapped = 0; spinlock_t *ptl; - struct folio *fault_folio = migrate->fault_page ? - page_folio(migrate->fault_page) : NULL; + struct folio *fault_folio; pte_t *ptep; again: + /* The fault page is in another folio once its folio has been split */ + fault_folio = migrate->fault_page ? + page_folio(migrate->fault_page) : NULL; + /* [start, addr) is collected if we get here after splitting a folio */ if (pmd_trans_huge(*pmdp) || !pmd_present(*pmdp)) { int ret = migrate_vma_collect_huge_pmd(pmdp, addr, end, walk, fault_folio); -- 2.56.0