From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 92450C47DAF for ; Mon, 22 Jan 2024 19:51:37 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=epISbfNM; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=epISbfNM; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TJgpJ1gmRz3dJ9 for ; Tue, 23 Jan 2024 06:51:36 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=epISbfNM; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=epISbfNM; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.133.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=david@redhat.com; receiver=lists.ozlabs.org) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 lists.ozlabs.org (Postfix) with ESMTPS id 4TJgct3X2xz3cTQ for ; Tue, 23 Jan 2024 06:43:26 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705952604; 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=tPsvEkVgYnC21FVdKrk6yuEGSmSqLr856lIR4lg3IVs=; b=epISbfNMsFymD8bEd6Gm/XAxGGp/qvluvDYWJZKLuaRZlKTUbkJc9plqovX5P5OAsFL5bP VNAdgmM9xuyQRlzHWEhXmStfBWVItleAfwUyeUgIPZRTTKG5SoFrVJ0BYCdxeOiFfCIdmR F8bHg61fXVmOLKZxn7f1KTHPJio/pfI= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705952604; 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=tPsvEkVgYnC21FVdKrk6yuEGSmSqLr856lIR4lg3IVs=; b=epISbfNMsFymD8bEd6Gm/XAxGGp/qvluvDYWJZKLuaRZlKTUbkJc9plqovX5P5OAsFL5bP VNAdgmM9xuyQRlzHWEhXmStfBWVItleAfwUyeUgIPZRTTKG5SoFrVJ0BYCdxeOiFfCIdmR F8bHg61fXVmOLKZxn7f1KTHPJio/pfI= 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-678-YpW0JN5UPxiQRu3cMsFdBw-1; Mon, 22 Jan 2024 14:43:18 -0500 X-MC-Unique: YpW0JN5UPxiQRu3cMsFdBw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (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 2508C87A38D; Mon, 22 Jan 2024 19:43:15 +0000 (UTC) Received: from t14s.redhat.com (unknown [10.39.195.114]) by smtp.corp.redhat.com (Postfix) with ESMTP id 192C124ED; Mon, 22 Jan 2024 19:43:08 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Subject: [PATCH v1 11/11] mm/memory: ignore writable bit in folio_pte_batch() Date: Mon, 22 Jan 2024 20:42:00 +0100 Message-ID: <20240122194200.381241-12-david@redhat.com> In-Reply-To: <20240122194200.381241-1-david@redhat.com> References: <20240122194200.381241-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Hildenbrand , Catalin Marinas , linux-mm@kvack.org, sparclinux@vger.kernel.org, Alexander Gordeev , Will Deacon , linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, Russell King , Matthew Wilcox , "Aneesh Kumar K.V" , "Naveen N. Rao" , Gerald Schaefer , Christian Borntraeger , Albert Ou , Ryan Roberts , Vasily Gorbik , Heiko Carstens , Nicholas Piggin , Paul Walmsley , linux-arm-kernel@lists.infradead.org, Dinh Nguyen , Palmer Dabbelt , Sven Schnelle , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" ... 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) won't care. Signed-off-by: David Hildenbrand --- mm/memory.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 341b2be845b6e..a26fd0669016b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -955,7 +955,7 @@ static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma, static inline pte_t __pte_batch_clear_ignored(pte_t pte) { - return pte_clear_soft_dirty(pte_mkclean(pte_mkold(pte))); + return pte_wrprotect(pte_clear_soft_dirty(pte_mkclean(pte_mkold(pte)))); } /* @@ -963,20 +963,29 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte) * pages of the same folio. * * All PTEs inside a PTE batch have the same PTE bits set, excluding the PFN. - * the accessed bit, dirty bit and soft-dirty bit. + * the accessed bit, dirty bit, soft-dirty bit and writable bit. + . 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) + pte_t *start_ptep, pte_t pte, int max_nr, bool *any_writable) { unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio); const pte_t *end_ptep = start_ptep + max_nr; pte_t expected_pte = __pte_batch_clear_ignored(pte_next_pfn(pte)); pte_t *ptep = start_ptep + 1; + bool writable; + + if (any_writable) + *any_writable = false; VM_WARN_ON_FOLIO(!pte_present(pte), folio); while (ptep != end_ptep) { - pte = __pte_batch_clear_ignored(ptep_get(ptep)); + pte = ptep_get(ptep); + if (any_writable) + writable = !!pte_write(pte); + pte = __pte_batch_clear_ignored(pte); if (!pte_same(pte, expected_pte)) break; @@ -989,6 +998,9 @@ static inline int folio_pte_batch(struct folio *folio, unsigned long addr, if (pte_pfn(pte) == folio_end_pfn) break; + if (any_writable) + *any_writable |= writable; + expected_pte = pte_next_pfn(expected_pte); ptep++; } @@ -1010,6 +1022,7 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma { struct page *page; struct folio *folio; + bool any_writable; int err, nr; page = vm_normal_page(src_vma, addr, pte); @@ -1024,7 +1037,8 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma * by keeping the batching logic separate. */ if (unlikely(!*prealloc && folio_test_large(folio) && max_nr != 1)) { - nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr); + nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, + &any_writable); if (folio_test_anon(folio)) { folio_ref_add(folio, nr); if (unlikely(folio_try_dup_anon_rmap_ptes(folio, page, @@ -1039,6 +1053,8 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma folio_dup_file_rmap_ptes(folio, page, nr); rss[mm_counter_file(page)] += nr; } + if (any_writable) + pte = pte_mkwrite(pte, src_vma); __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte, addr, nr); return nr; -- 2.43.0