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 727393B52E2 for ; Fri, 9 Oct 2026 04:17:19 +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=1791519448; cv=none; b=JuAOhDjslfazAhNjFUzoYhGrRhJ7b+MQPvs4zB5M2LG1LhzXNg9q2jyBLrTfR8/3rUYwwwsv9jbWsd2CeNtsHreRmPN+urhGb4oIflF5gohPrrmd4rJmwfCwF0Nt2+cjKplPuMiXOvQy7tJtrakpnX7uKCpDtIIleRYMbAttrHk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791519448; c=relaxed/simple; bh=Up6RI9uVC2c+wIJbpZm0V5bMiNhWTdbZgDD4nkbk5ts=; h=Date:To:From:Subject:Message-Id; b=pk/fIidgVnCGGBIpOwBc1rp8786Umz6qi6kdBUitJntUT+Zw71/IeiSkgXh3KkRh5ut0xyW4g/uFvX5hfYaSpYyPQZAu8GiQW7PvPceamSvGZ/dSl/Z5rGlYRrHbboArdN/lcjpWAY5KdWx0MCoRMza/ncsqWv4AiG2Lh2dAfMM= 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=QyBfy+Mu; 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="QyBfy+Mu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A4DB11F000FF; Fri, 9 Oct 2026 04:17:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791519439; bh=UlLmMMicPljVsfClOsUHCrhuDVouNNDgCxmsoKw8VE0=; h=Date:To:From:Subject; b=QyBfy+MuEL8duDFjJfwcuF0AI7qk8lPDlf4uA16MPMRtfUOp6UulmoMnOGSA5GdoR aOnSFEZul5Bo2W7GZlri1b8CrbppgsSchzTqtR+l8SZz8hX4BYwFhIUa0uZEKF9I/q uDiqxsaBL9L1mR3YWBDvpkxHZD0ojBK/hpmXydwo= Date: Thu, 08 Oct 2026 21:17:19 -0700 To: mm-commits@vger.kernel.org,sshegde@linux.ibm.com,rppt@kernel.org,ritesh.list@gmail.com,rdunlap@infradead.org,qi.zheng@linux.dev,osalvador@suse.de,npiggin@gmail.com,mpe@ellerman.id.au,maddy@linux.ibm.com,ljs@kernel.org,lance.yang@linux.dev,david@kernel.org,corbet@lwn.net,chleroy@kernel.org,muchun.song@linux.dev,akpm@linux-foundation.org From: Andrew Morton Subject: [folded-merged] powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages-fix.patch removed from -mm tree Message-Id: <20261009041719.A4DB11F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: fixup! powerpc/mm: switch device DAX to shared tail vmemmap pages has been removed from the -mm tree. Its filename was powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages-fix.patch This patch was dropped because it was folded into powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages.patch ------------------------------------------------------ From: Muchun Song Subject: fixup! powerpc/mm: switch device DAX to shared tail vmemmap pages Date: Wed, 30 Sep 2026 23:28:26 +0800 The PowerPC radix path takes one reference for every PTE that maps the shared tail page. Unlike the generic path, get_page() lets the counter continue after it becomes non-positive and eventually cycle to zero. Use try_get_page() so vmemmap population fails before the shared page reference count can cycle, matching the generic implementation. Link: https://lore.kernel.org/20260930152826.76084-1-songmuchun@bytedance.com Signed-off-by: Muchun Song Signed-off-by: Andrew Morton Cc: David Hildenbrand Cc: Oscar Salvador Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Jonathan Corbet Cc: Lorenzo Stoakes Cc: Mike Rapoport Cc: Qi Zheng Cc: Nicholas Piggin Cc: Christophe Leroy Cc: Ritesh Harjani (IBM) Cc: Shrikanth Hegde Cc: Randy Dunlap Cc: Lance Yang --- arch/powerpc/mm/book3s64/radix_pgtable.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/arch/powerpc/mm/book3s64/radix_pgtable.c~powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages-fix +++ a/arch/powerpc/mm/book3s64/radix_pgtable.c @@ -1042,13 +1042,17 @@ static pte_t * __meminit radix__vmemmap_ /* * When a PTE/PMD entry is freed from the init_mm * there's a free_pages() call to this page allocated - * above. Thus this get_page() is paired with the + * above. Thus this try_get_page() is paired with the * put_page_testzero() on the freeing path. * This can only called by certain ZONE_DEVICE path, * and through vmemmap_populate_compound_pages() when * slab is available. + * + * Use try_get_page() to prevent the shared page refcount + * from overflowing. */ - get_page(reuse); + if (!try_get_page(reuse)) + return NULL; p = page_to_virt(reuse); pr_debug("Tail page reuse vmemmap mapping\n"); } _ Patches currently in -mm which might be from muchun.song@linux.dev are mm-sparse-vmemmap-factor-out-shared-vmemmap-tail-page-allocation.patch mm-sparse-vmemmap-allocate-shared-tail-page-array-dynamically.patch mm-sparse-vmemmap-introduce-config_vmemmap_optimization.patch mm-sparse-vmemmap-open-code-init_compound_tail.patch mm-sparse-vmemmap-prepare-dax-vmemmap-population-for-compound-page-orders.patch mm-sparse-vmemmap-set-compound-page-order-for-device-dax.patch mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages.patch mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages.patch mm-sparse-vmemmap-drop-the-extra-tail-page-from-device-dax-reservation.patch mm-sparse-vmemmap-drop-unused-section_nr_vmemmap_pages-arguments.patch documentation-mm-update-dax-vmemmap-deduplication-docs.patch mm-sparse-vmemmap-drop-vmemmap_populate_dax.patch mm-sparse-vmemmap-support-device-dax-in-common-vmemmap-path.patch mm-sparse-vmemmap-drop-device-dax-specific-population-path.patch mm-sparse-vmemmap-remove-the-unused-ptpfn-argument.patch mm-sparse-vmemmap-open-code-vmemmap_populate_address.patch mm-mm_init-add-zone-mismatch-warning-during-page-init.patch