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=1794606410; b=rdUUnd5iekUDUIOzL4QtK0fTkcGjPJ2npMHhWT90Kcn7Unip2/MQguXOcjfTZ9fcmnlA j8eYctBBcMdYO6yJPaCg0zKiCD5/6Nikz7ugTLalS/IkB/iYM8U1NA70wiMN7fQJS+isI ekml4VQH7uYDp6jMVdQKfTyjoF050ip4ZUXu6slgseQkN9f0RhcQz0bxX2DXbxIVv5z9F FlwI96Hrc5OEc+YPl3cuZFVtiORtA21BpSLk6Bzo3Saw17IRa9w8HaOHNKiTdcGi/oROn i1T2w7YbK4ew3a8/GWMlpN0pJHSgp/e/cjDA+EggwtXbF0Ijpho9z0cKCSB/P9LcK0Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794606410; 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=SbhSMWJZhoke2qAl0UjjAwvOzQBu4RiiX5KWSyo8Ios=; b=pVzHVkt3kjPzhUYHwiEgHMrlICPqvL0bjzmXybF3PqAAt7w24CqQh+qmYobbmJFsatfR f748pziQDVJBMUJGEXdX1ZoBo7P/AfnikVGvLOngw0f1oKCBInmMZZe4CeTjILqxPHJrT RwG+rVdTboogTGOCeggayrSruP/db+WAQadBtB9VhvHk3Pt2T+u1fm//1wNCXyZ/NPcJ8 KHDQg4wNbJyg/I8taENK1ZjD5h+tjT8SeEelCHUNbtJ84vBCqTOdX1lBK/MJCgpV8nixO tRJmxT+VcaxPzx/mYeOnQDCALU2R+0YWJ0hmrJwKh6UPH89hmgexyXs6YCjPGlcCoww== 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=hU8D9s6j; 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 6BC5B606A333; Fri, 13 Nov 2026 21:46:50 +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=hU8D9s6j Received: by smtp.kernel.org (Postfix) with ESMTPSA id A20511F000C7; Fri, 13 Nov 2026 21:46:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794606410; bh=SbhSMWJZhoke2qAl0UjjAwvOzQBu4RiiX5KWSyo8Ios=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=hU8D9s6joQEtJUegFkkfvSvT2iHHsk8iGzhEVv/uUzwH0PWF1GXbVRGwT4bHxvrfn 2EZcYgGgzpl8nEakZMp2ukOZuBhscxUIKsBNmlylUAMN4zuHbEKxOtMIyY9uSkF3Sq +Ej6ej6y+vU3SBRKADrtJgUejWo4lRa4QkqfhHi1GffmudNcx3vkK4swiTwZxZLEYE 1wUR1VOSl9R38mrkzmCSOrdHetR+zQ1eXRJH8U36PauhLGeMWgnv2UYVqE79iEnSFr WP5M3yisa3L1br9ED2b+ibn17z430NFhzGSE5k7bC4vKyU2xfkay79I6BxX4AKR50C iWuLW73rJ9YDA== From: "Lorenzo Stoakes (ARM)" Date: Fri, 13 Nov 2026 21:45:25 +0000 Subject: [PATCH v2 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: <20261113-mason-migrate-et-al-fixes-v2-7-50a2ed382b61@kernel.org> References: <20261113-mason-migrate-et-al-fixes-v2-0-50a2ed382b61@kernel.org> In-Reply-To: <20261113-mason-migrate-et-al-fixes-v2-0-50a2ed382b61@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=1695; i=ljs@kernel.org; h=from:subject:message-id; bh=aaALv9FtajCSrXDaml0a4kDLKsK9tSim3Q9wP7uXhCw=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLK+t/x8F1Tw/u3iVyvYXMvz/ZR1VY7MO7cw5/PtKw+8P m7c+0LMpKOUhUGMi0FWTJHl+Rfx/UEiYfM6L/i7wcxhZQIZwsDFKQATyZRk+CtYFmrVcoe3YOfd 6OoH2YbLy7OzC3qdDjtsmn6gyLJUrI7hn55t+VeLKJ3+pANvMyYWqd8yijPct0XJ/lrK3MM606S XswMA 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: stable@vger.kernel.org Signed-off-by: Josef Bacik [ ljs: pared down commit message ] Tested-by: Gregory Price (Meta) 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