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 X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 639FAC32792 for ; Mon, 30 Sep 2019 12:29:37 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 15BE520815 for ; Mon, 30 Sep 2019 12:29:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 15BE520815 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6211A6B0005; Mon, 30 Sep 2019 08:29:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5F7256B0008; Mon, 30 Sep 2019 08:29:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4E6816B000A; Mon, 30 Sep 2019 08:29:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0151.hostedemail.com [216.40.44.151]) by kanga.kvack.org (Postfix) with ESMTP id 0D44A6B0005 for ; Mon, 30 Sep 2019 08:29:32 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id A6DFF180AD804 for ; Mon, 30 Sep 2019 12:29:31 +0000 (UTC) X-FDA: 75991517742.25.hot13_531d961e91129 X-HE-Tag: hot13_531d961e91129 X-Filterd-Recvd-Size: 10428 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Mon, 30 Sep 2019 12:29:31 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E8F02AFE8; Mon, 30 Sep 2019 12:29:28 +0000 (UTC) From: Vlastimil Babka To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Qian Cai , "Kirill A. Shutemov" , Matthew Wilcox , Mel Gorman , Michal Hocko , Vlastimil Babka , Dmitry Vyukov , Walter Wu , Andrey Ryabinin Subject: [PATCH v2 2/3] mm, page_owner: decouple freeing stack trace from debug_pagealloc Date: Mon, 30 Sep 2019 14:29:15 +0200 Message-Id: <20190930122916.14969-3-vbabka@suse.cz> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190930122916.14969-1-vbabka@suse.cz> References: <20190930122916.14969-1-vbabka@suse.cz> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The commit 8974558f49a6 ("mm, page_owner, debug_pagealloc: save and dump freeing stack trace") enhanced page_owner to also store freeing stack tra= ce, when debug_pagealloc is also enabled. KASAN would also like to do this [1= ] to improve error reports to debug e.g. UAF issues. Kirill has suggested that= the freeing stack trace saving should be also possible to be enabled separate= ly. This patch therefore introduces a new kernel parameter page_owner_free to enable the functionality in addition to the existing page_owner parameter= . The free stack saving is thus enabled in these cases: 1) booting with page_owner=3Don and debug_pagealloc=3Don 2) booting a KASAN kernel with page_owner=3Don 3) booting with page_owner=3Don and page_owner_free=3Don To minimize runtime CPU and memory overhead when not boot-time enabled, t= he patch introduces a new static key and struct page_ext_operations. [1] https://bugzilla.kernel.org/show_bug.cgi?id=3D203967 Suggested-by: Dmitry Vyukov Suggested-by: Walter Wu Suggested-by: Andrey Ryabinin Suggested-by: Kirill A. Shutemov Signed-off-by: Vlastimil Babka --- .../admin-guide/kernel-parameters.txt | 8 ++ Documentation/dev-tools/kasan.rst | 3 + include/linux/page_owner.h | 1 + mm/page_ext.c | 1 + mm/page_owner.c | 90 +++++++++++++------ 5 files changed, 78 insertions(+), 25 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentat= ion/admin-guide/kernel-parameters.txt index 944e03e29f65..14dcb66e3457 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3237,6 +3237,14 @@ we can turn it on. on: enable the feature =20 + page_owner_free=3D + [KNL] When enabled together with page_owner, store also + the stack of who frees a page, for error page dump + purposes. This is also implicitly enabled by + debug_pagealloc=3Don or KASAN, so only page_owner=3Don is + sufficient in those cases. + on: enable the feature + page_poison=3D [KNL] Boot-time parameter changing the state of poisoning on the buddy allocator, available with CONFIG_PAGE_POISONING=3Dy. diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/= kasan.rst index b72d07d70239..525296121d89 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -41,6 +41,9 @@ smaller binary while the latter is 1.1 - 2 times faster= . Both KASAN modes work with both SLUB and SLAB memory allocators. For better bug detection and nicer reporting, enable CONFIG_STACKTRACE. =20 +To augment reports with last allocation and freeing stack of the physica= l page, +it is recommended to enable also CONFIG_PAGE_OWNER and boot with page_ow= ner=3Don. + To disable instrumentation for specific files or directories, add a line similar to the following to the respective kernel Makefile: =20 diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h index 8679ccd722e8..0888dd70cc61 100644 --- a/include/linux/page_owner.h +++ b/include/linux/page_owner.h @@ -7,6 +7,7 @@ #ifdef CONFIG_PAGE_OWNER extern struct static_key_false page_owner_inited; extern struct page_ext_operations page_owner_ops; +extern struct page_ext_operations page_owner_free_ops; =20 extern void __reset_page_owner(struct page *page, unsigned int order); extern void __set_page_owner(struct page *page, diff --git a/mm/page_ext.c b/mm/page_ext.c index 4ade843ff588..5724b637939a 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -61,6 +61,7 @@ static struct page_ext_operations *page_ext_ops[] =3D { #ifdef CONFIG_PAGE_OWNER &page_owner_ops, + &page_owner_free_ops, #endif #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT) &page_idle_ops, diff --git a/mm/page_owner.c b/mm/page_owner.c index d3cf5d336ccf..a668a735b9b6 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -24,13 +24,16 @@ struct page_owner { short last_migrate_reason; gfp_t gfp_mask; depot_stack_handle_t handle; -#ifdef CONFIG_DEBUG_PAGEALLOC +}; + +struct page_owner_free { depot_stack_handle_t free_handle; -#endif }; =20 -static bool page_owner_disabled =3D true; +static bool page_owner_enabled =3D false; +static bool page_owner_free_enabled =3D false; DEFINE_STATIC_KEY_FALSE(page_owner_inited); +static DEFINE_STATIC_KEY_FALSE(page_owner_free_stack); =20 static depot_stack_handle_t dummy_handle; static depot_stack_handle_t failure_handle; @@ -44,7 +47,7 @@ static int __init early_page_owner_param(char *buf) return -EINVAL; =20 if (strcmp(buf, "on") =3D=3D 0) - page_owner_disabled =3D false; + page_owner_enabled =3D true; =20 return 0; } @@ -52,10 +55,30 @@ early_param("page_owner", early_page_owner_param); =20 static bool need_page_owner(void) { - if (page_owner_disabled) + return page_owner_enabled; +} + +static int __init early_page_owner_free_param(char *buf) +{ + if (!buf) + return -EINVAL; + + if (strcmp(buf, "on") =3D=3D 0) + page_owner_free_enabled =3D true; + + return 0; +} +early_param("page_owner_free", early_page_owner_free_param); + +static bool need_page_owner_free(void) { + + if (!page_owner_enabled) return false; =20 - return true; + if (IS_ENABLED(CONFIG_KASAN) || debug_pagealloc_enabled()) + page_owner_free_enabled =3D true; + + return page_owner_free_enabled; } =20 static __always_inline depot_stack_handle_t create_dummy_stack(void) @@ -84,7 +107,7 @@ static noinline void register_early_stack(void) =20 static void init_page_owner(void) { - if (page_owner_disabled) + if (!page_owner_enabled) return; =20 register_dummy_stack(); @@ -94,17 +117,36 @@ static void init_page_owner(void) init_early_allocated_pages(); } =20 +static void init_page_owner_free(void) +{ + if (!page_owner_enabled || !page_owner_free_enabled) + return; + + static_branch_enable(&page_owner_free_stack); +} + struct page_ext_operations page_owner_ops =3D { .size =3D sizeof(struct page_owner), .need =3D need_page_owner, .init =3D init_page_owner, }; =20 +struct page_ext_operations page_owner_free_ops =3D { + .size =3D sizeof(struct page_owner_free), + .need =3D need_page_owner_free, + .init =3D init_page_owner_free, +}; + static inline struct page_owner *get_page_owner(struct page_ext *page_ex= t) { return (void *)page_ext + page_owner_ops.offset; } =20 +static inline struct page_owner_free *get_page_owner_free(struct page_ex= t *page_ext) +{ + return (void *)page_ext + page_owner_free_ops.offset; +} + static inline bool check_recursive_alloc(unsigned long *entries, unsigned int nr_entries, unsigned long ip) @@ -148,25 +190,21 @@ void __reset_page_owner(struct page *page, unsigned= int order) { int i; struct page_ext *page_ext; -#ifdef CONFIG_DEBUG_PAGEALLOC depot_stack_handle_t handle =3D 0; - struct page_owner *page_owner; + struct page_owner_free *page_owner_free; =20 - if (debug_pagealloc_enabled()) + if (static_branch_unlikely(&page_owner_free_stack)) handle =3D save_stack(GFP_NOWAIT | __GFP_NOWARN); -#endif =20 page_ext =3D lookup_page_ext(page); if (unlikely(!page_ext)) return; for (i =3D 0; i < (1 << order); i++) { __clear_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); -#ifdef CONFIG_DEBUG_PAGEALLOC - if (debug_pagealloc_enabled()) { - page_owner =3D get_page_owner(page_ext); - page_owner->free_handle =3D handle; + if (static_branch_unlikely(&page_owner_free_stack)) { + page_owner_free =3D get_page_owner_free(page_ext); + page_owner_free->free_handle =3D handle; } -#endif page_ext =3D page_ext_next(page_ext); } } @@ -414,6 +452,7 @@ void __dump_page_owner(struct page *page) { struct page_ext *page_ext =3D lookup_page_ext(page); struct page_owner *page_owner; + struct page_owner_free *page_owner_free; depot_stack_handle_t handle; unsigned long *entries; unsigned int nr_entries; @@ -450,16 +489,17 @@ void __dump_page_owner(struct page *page) stack_trace_print(entries, nr_entries, 0); } =20 -#ifdef CONFIG_DEBUG_PAGEALLOC - handle =3D READ_ONCE(page_owner->free_handle); - if (!handle) { - pr_alert("page_owner free stack trace missing\n"); - } else { - nr_entries =3D stack_depot_fetch(handle, &entries); - pr_alert("page last free stack trace:\n"); - stack_trace_print(entries, nr_entries, 0); + if (static_branch_unlikely(&page_owner_free_stack)) { + page_owner_free =3D get_page_owner_free(page_ext); + handle =3D READ_ONCE(page_owner_free->free_handle); + if (!handle) { + pr_alert("page_owner free stack trace missing\n"); + } else { + nr_entries =3D stack_depot_fetch(handle, &entries); + pr_alert("page last free stack trace:\n"); + stack_trace_print(entries, nr_entries, 0); + } } -#endif =20 if (page_owner->last_migrate_reason !=3D -1) pr_alert("page has been migrated, last migrate reason: %s\n", --=20 2.23.0