From nobody Wed Dec 24 03:14:45 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 0FE6661691 for ; Mon, 29 Jan 2024 12:48:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706532512; cv=none; b=RAGdcn3IHTh+mZz2MD4l8ke5X55tvM9VA4yUrRejWLyor2Nz9fW6SOHX+im4DS3yyuJ/r6Y2HYPxGy0AiyvkiMhn0s55psYVgW947z0YWFsW+hwdtg1lgiqn7ObENAVSMOdAWNQ6durKvxHuB5bYe9RJYzUaNPBVXp4YP7uJMrE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706532512; c=relaxed/simple; bh=WijXHNN6cEbo4+hvn2lkZ0k2/r3mW8vSMOQ+qEBDy2U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hOWCFrFUr4r8bnh52Ih+oyE0tJTiJ7szV2UV3brm5EuQz8CYdbl7OLumxYaf4L29SIoi0r2T0D4zZaBEXcYioeO+Fp4GtSJGTxiTRt8pfXzlf3qWxbDDiba4G+pAB71aqEGM90uo9GJlD6vLPqGUvszjMfMh6MWWoFQRwgeojak= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KjeRfVvG; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KjeRfVvG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706532510; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kPofd6LlL0FntZsVxpMLUzci6vAQKc1aG/cPn5S11O0=; b=KjeRfVvG+5QpX2CYiPT2SE6634umI5mDUdNheSMhDv0jw9AOx1JJXHZTWJwuSTQXpFzU+L 8BUmSoVQ8cOop6J49klZIrAlGwqjDZlLKVZbiyoXzrlWP9B7XCUA0JOxmuZ9WWyC2q/Wmf 8Ec0Eb/dlzQUNIwNa/Lic4sRwMRwQk0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-413-PehoyRVrMfeAXOFdLIlxVA-1; Mon, 29 Jan 2024 07:48:26 -0500 X-MC-Unique: PehoyRVrMfeAXOFdLIlxVA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 898A186F129; Mon, 29 Jan 2024 12:48:25 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.194.46]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4CC6D8B; Mon, 29 Jan 2024 12:48:20 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Matthew Wilcox , Ryan Roberts , Russell King , Catalin Marinas , Will Deacon , Dinh Nguyen , Michael Ellerman , Nicholas Piggin , Christophe Leroy , "Aneesh Kumar K.V" , "Naveen N. Rao" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , "David S. Miller" , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org Subject: [PATCH v3 15/15] mm/memory: ignore writable bit in folio_pte_batch() Date: Mon, 29 Jan 2024 13:46:49 +0100 Message-ID: <20240129124649.189745-16-david@redhat.com> In-Reply-To: <20240129124649.189745-1-david@redhat.com> References: <20240129124649.189745-1-david@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 Content-Type: text/plain; charset="utf-8" ... and conditionally return to the caller if any PTE except the first one is writable. fork() has to make sure to properly write-protect in case any PTE is writable. Other users (e.g., page unmaping) are expected to not care. Reviewed-by: Ryan Roberts Signed-off-by: David Hildenbrand --- mm/memory.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index b2ec2b6b54c7..b05fd28dbce1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -968,7 +968,7 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte= , fpb_t flags) pte =3D pte_mkclean(pte); if (likely(flags & FPB_IGNORE_SOFT_DIRTY)) pte =3D pte_clear_soft_dirty(pte); - return pte_mkold(pte); + return pte_wrprotect(pte_mkold(pte)); } =20 /* @@ -976,21 +976,32 @@ static inline pte_t __pte_batch_clear_ignored(pte_t p= te, fpb_t flags) * pages of the same folio. * * All PTEs inside a PTE batch have the same PTE bits set, excluding the P= FN, - * the accessed bit, dirty bit (with FPB_IGNORE_DIRTY) and soft-dirty bit - * (with FPB_IGNORE_SOFT_DIRTY). + * the accessed bit, writable bit, dirty bit (with FPB_IGNORE_DIRTY) and + * soft-dirty bit (with FPB_IGNORE_SOFT_DIRTY). + * + * If "any_writable" is set, it will indicate if any other PTE besides the + * first (given) PTE is writable. */ static inline int folio_pte_batch(struct folio *folio, unsigned long addr, - pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags) + pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags, + bool *any_writable) { unsigned long folio_end_pfn =3D folio_pfn(folio) + folio_nr_pages(folio); const pte_t *end_ptep =3D start_ptep + max_nr; pte_t expected_pte =3D __pte_batch_clear_ignored(pte_next_pfn(pte), flags= ); pte_t *ptep =3D start_ptep + 1; + bool writable; + + if (any_writable) + *any_writable =3D false; =20 VM_WARN_ON_FOLIO(!pte_present(pte), folio); =20 while (ptep !=3D end_ptep) { - pte =3D __pte_batch_clear_ignored(ptep_get(ptep), flags); + pte =3D ptep_get(ptep); + if (any_writable) + writable =3D !!pte_write(pte); + pte =3D __pte_batch_clear_ignored(pte, flags); =20 if (!pte_same(pte, expected_pte)) break; @@ -1003,6 +1014,9 @@ static inline int folio_pte_batch(struct folio *folio= , unsigned long addr, if (pte_pfn(pte) =3D=3D folio_end_pfn) break; =20 + if (any_writable) + *any_writable |=3D writable; + expected_pte =3D pte_next_pfn(expected_pte); ptep++; } @@ -1024,6 +1038,7 @@ copy_present_ptes(struct vm_area_struct *dst_vma, str= uct vm_area_struct *src_vma { struct page *page; struct folio *folio; + bool any_writable; fpb_t flags =3D 0; int err, nr; =20 @@ -1044,7 +1059,8 @@ copy_present_ptes(struct vm_area_struct *dst_vma, str= uct vm_area_struct *src_vma if (!vma_soft_dirty_enabled(src_vma)) flags |=3D FPB_IGNORE_SOFT_DIRTY; =20 - nr =3D folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags); + nr =3D folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags, + &any_writable); folio_ref_add(folio, nr); if (folio_test_anon(folio)) { if (unlikely(folio_try_dup_anon_rmap_ptes(folio, page, @@ -1058,6 +1074,8 @@ copy_present_ptes(struct vm_area_struct *dst_vma, str= uct vm_area_struct *src_vma folio_dup_file_rmap_ptes(folio, page, nr); rss[mm_counter_file(folio)] +=3D nr; } + if (any_writable) + pte =3D pte_mkwrite(pte, src_vma); __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte, addr, nr); return nr; --=20 2.43.0