From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B3D4531F99A; Thu, 9 Jul 2026 22:49:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783637394; cv=none; b=Zst8QyoiCeUryXJ4WvYB0dNMntYnTcR3zUO8yMo5c+ZoE/ruRb478qI610EwXQfhAEV8++E5H/NVt457HZErjafFpnI+xkB8iWZvlYLP3KDCZlygjm+ycyJZTCE/Wl/0EgNEQDxA3du4KOeJgzdMNPHdEDAVu63qmcE/eJvF74U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783637394; c=relaxed/simple; bh=Okqp7MLfijeHbLRmU4RLIPd328cKzS9iZVT5PGhMZE4=; h=Date:To:From:Subject:Message-Id; b=p874YptvTT9rx8OagFyUVZxq29qOw+Y2scIS9KrYGcLhNZjqiKPzmg7loQ8w2f8oVRdzi4WcqVJWjVyQ33HkIsQ2BikaxRJPJ3RMtxenL73zft348RSXF8mfYKrLrD9Zh+Vsbf3aPTs4bUFedAnuV1MasYNULgwx0ZWFephzu4k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=CMJW5v9Y; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="CMJW5v9Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 556241F00A3A; Thu, 9 Jul 2026 22:49:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783637392; bh=0Lo1AHINaaeIUQHLTwQMOvobS1f/aUGZxPodZlyVvU4=; h=Date:To:From:Subject; b=CMJW5v9YqhldQcYr35/PgaaX3oHYUr2UH3EBL+C80vpTC2sersOC0+gYLWyA3vJqM gCxsn4t28PhfRmiiwm6VwfQfs/NkLzEuwK6Ast/934Eb2Y7vSHj3xX9DNqUFrY4i3L 5aVVZWlqH3c1cgIxO6v4brW5SQHv2XzhWt2493hk= Date: Thu, 09 Jul 2026 15:49:51 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,stable@vger.kernel.org,sj@kernel.org,ljs@kernel.org,lance.yang@linux.dev,klarasmodin@gmail.com,david@kernel.org,balbirs@nvidia.com,richard.weiyang@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-page_vma_mapped-fix-device-private-pmd-handling.patch removed from -mm tree Message-Id: <20260709224952.556241F00A3A@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/page_vma_mapped: fix device-private PMD handling has been removed from the -mm tree. Its filename was mm-page_vma_mapped-fix-device-private-pmd-handling.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Wei Yang Subject: mm/page_vma_mapped: fix device-private PMD handling Date: Tue, 30 Jun 2026 02:15:40 +0000 Commit 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries") introduced the concept of device-private PMD entries, but did not correctly update the rmap walk code to account for them. As a result, when page_vma_mapped_walk() encounters device-private PMD entries, it takes no action other than to acquire the PMD lock and exit. However this is highly problematic for two reasons - firstly, device private entries possess a PFN so check_pmd() needs to be called to ensure an overlapping PFN range. Secondly, and more importantly, if PVMW_MIGRATION is set the caller assumes the returned entry is a migration entry, resulting in memory corruption when the caller tries to interpret the device private entry as such. In addition, commit 146287290023 ("mm/huge_memory: implement device-private THP splitting") allowed device private PMDs to be split like THP mappings, but again did not update this code path. As a result, we might race a PMD split prior to acquiring the PMD lock. This patch addresses all of these issues by invoking check_pmd(), ensuring PMVW_MIGRATION is not set and checks whether a split raced us we do for PMD THP and migration entries. Instead of checking for a subset of the cases after taking the pmd_lock(), put device-private along with pmd_trans_huge() and pmd_is_migration_entry(). Also remove thp_migration_supported() as it is already guarded by pmd_is_migration_entry(). [akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David] Link: https://lore.kernel.org/20260630021540.17297-1-richard.weiyang@gmail.com Fixes: 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries") Signed-off-by: Wei Yang Suggested-by: David Hildenbrand Reviewed-by: Lance Yang Acked-by: Balbir Singh Tested-by: Klara Modin Cc: SeongJae Park Cc: Zi Yan Cc: Lorenzo Stoakes Cc: q Signed-off-by: Andrew Morton --- mm/page_vma_mapped.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) --- a/mm/page_vma_mapped.c~mm-page_vma_mapped-fix-device-private-pmd-handling +++ a/mm/page_vma_mapped.c @@ -243,21 +243,31 @@ restart: */ pmde = pmdp_get_lockless(pvmw->pmd); - if (pmd_trans_huge(pmde) || pmd_is_migration_entry(pmde)) { + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + (pmd_trans_huge(pmde) || pmd_is_migration_entry(pmde) || + pmd_is_device_private_entry(pmde))) { pvmw->ptl = pmd_lock(mm, pvmw->pmd); pmde = *pvmw->pmd; - if (!pmd_present(pmde)) { + if (pmd_is_migration_entry(pmde)) { softleaf_t entry; - if (!thp_migration_supported() || - !(pvmw->flags & PVMW_MIGRATION)) + if (!(pvmw->flags & PVMW_MIGRATION)) return not_found(pvmw); entry = softleaf_from_pmd(pmde); + if (!check_pmd(softleaf_to_pfn(entry), pvmw)) + return not_found(pvmw); + return true; + } else if (pmd_is_device_private_entry(pmde)) { + softleaf_t entry; - if (!softleaf_is_migration(entry) || - !check_pmd(softleaf_to_pfn(entry), pvmw)) + if (pvmw->flags & PVMW_MIGRATION) + return not_found(pvmw); + entry = softleaf_from_pmd(pmde); + if (!check_pmd(softleaf_to_pfn(entry), pvmw)) return not_found(pvmw); return true; + } else if (!pmd_present(pmde)) { + return not_found(pvmw); } if (likely(pmd_trans_huge(pmde))) { if (pvmw->flags & PVMW_MIGRATION) @@ -266,17 +276,10 @@ restart: return not_found(pvmw); return true; } - /* THP pmd was split under us: handle on pte level */ + /* THP/device-private pmd was split under us: handle on pte level */ spin_unlock(pvmw->ptl); pvmw->ptl = NULL; } else if (!pmd_present(pmde)) { - const softleaf_t entry = softleaf_from_pmd(pmde); - - if (softleaf_is_device_private(entry)) { - pvmw->ptl = pmd_lock(mm, pvmw->pmd); - return true; - } - if ((pvmw->flags & PVMW_SYNC) && thp_vma_suitable_order(vma, pvmw->address, PMD_ORDER) && _ Patches currently in -mm which might be from richard.weiyang@gmail.com are