From patchwork Thu Jan 25 19:32:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13531602 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 B5950C47258 for ; Thu, 25 Jan 2024 19:36:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=VAD/ndQy+spWWgURR0hBDEqClANdc1MlNjZWW6S++PM=; b=bMieCAqOGM80ex /M+oPrKpop+agmnl6irAtoe5HuORJnM2IJ0r9qeWYcXST5zTARkYpOJjfCzRjwaZeOv9/LLgBi8y+ miNnrzq4DeDuxfjqODeieCkANqlpNdWaT3CcD2mn7udqwrc55N0jQKKFBwSlc82WbJiVGaaMa8Xlh +ygYjYnwd+CoLAIbadmRYoLGyULqAW+m7DjhN2gm46PvQm72plhw+0a4MxIle1q9dGij8+u+a4uXA iu5cDfyEpmPu/FIKxJkpBXS+oGkHGlQwWCLY4Ojn6Huk6MSJrd/+AhZnBU1f02fpJMifsjTtIXylf dtDQM3moYLprhAMXRWpA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rT5WM-00000001a6J-0If5; Thu, 25 Jan 2024 19:36:18 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rT5UO-00000001YZv-3vHw for linux-riscv@lists.infradead.org; Thu, 25 Jan 2024 19:34:23 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706211255; 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=KHoljgu5TCYuagRFnizBrkwj14eAAX8FKS7MlgFMZ5g=; b=G6VEVlrESdCzZVk3TzB32BWFzctyFkbORZqYqmG/7p4gu4qFhgtxFr43oCnMv+zb5pbZEy NB9Aakho5Ojm7OI5ReQPoOwxk9zkLRmu/Io6f3OXI3mQocK9kSEq/lPap+qMd3jd87E+fz iYnTTsyRuCuS7Q1a4jE1O2mgl4VHOls= 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-403-CrPk6FszOsesuz_bqE2sxg-1; Thu, 25 Jan 2024 14:34:06 -0500 X-MC-Unique: CrPk6FszOsesuz_bqE2sxg-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (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 88F408432A2; Thu, 25 Jan 2024 19:34:05 +0000 (UTC) Received: from t14s.redhat.com (unknown [10.39.193.154]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3B6DA492BC6; Thu, 25 Jan 2024 19:34:00 +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 v2 15/15] mm/memory: ignore writable bit in folio_pte_batch() Date: Thu, 25 Jan 2024 20:32:27 +0100 Message-ID: <20240125193227.444072-16-david@redhat.com> In-Reply-To: <20240125193227.444072-1-david@redhat.com> References: <20240125193227.444072-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240125_113417_323613_CDB055BF X-CRM114-Status: GOOD ( 16.12 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org ... 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 b3f035fe54c8d..64442da3df6d4 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 = pte_mkclean(pte); if (likely(flags & FPB_IGNORE_SOFT_DIRTY)) pte = pte_clear_soft_dirty(pte); - return pte_mkold(pte); + return pte_wrprotect(pte_mkold(pte)); } /* @@ -976,21 +976,32 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) * 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 (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 = 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), flags); 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), flags); + pte = ptep_get(ptep); + if (any_writable) + writable = !!pte_write(pte); + pte = __pte_batch_clear_ignored(pte, flags); 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) == folio_end_pfn) break; + if (any_writable) + *any_writable |= writable; + expected_pte = pte_next_pfn(expected_pte); ptep++; } @@ -1024,6 +1038,7 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma { struct page *page; struct folio *folio; + bool any_writable; fpb_t flags = 0; int err, nr; @@ -1044,7 +1059,8 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma if (!vma_soft_dirty_enabled(src_vma)) flags |= FPB_IGNORE_SOFT_DIRTY; - nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags); + nr = 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, 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;