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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 35FA0C4CEC6 for ; Thu, 12 Sep 2019 13:53:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 00D052084D for ; Thu, 12 Sep 2019 13:53:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 00D052084D 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 6E24B6B0005; Thu, 12 Sep 2019 09:53:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 692D86B0006; Thu, 12 Sep 2019 09:53:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5A7F76B0007; Thu, 12 Sep 2019 09:53:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0241.hostedemail.com [216.40.44.241]) by kanga.kvack.org (Postfix) with ESMTP id 3A14F6B0005 for ; Thu, 12 Sep 2019 09:53:53 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id AAFDF82437CF for ; Thu, 12 Sep 2019 13:53:52 +0000 (UTC) X-FDA: 75926411904.03.honey84_3edd4eea15d2a X-HE-Tag: honey84_3edd4eea15d2a X-Filterd-Recvd-Size: 7909 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Thu, 12 Sep 2019 13:53:51 +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 AD654B7D4; Thu, 12 Sep 2019 13:53:49 +0000 (UTC) Subject: Re: [PATCH v3] mm/kasan: dump alloc and free stack for page allocator To: Qian Cai , Walter Wu Cc: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Matthias Brugger , Andrew Morton , Martin Schwidefsky , Andrey Konovalov , Arnd Bergmann , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com References: <20190911083921.4158-1-walter-zh.wu@mediatek.com> <5E358F4B-552C-4542-9655-E01C7B754F14@lca.pw> From: Vlastimil Babka Message-ID: Date: Thu, 12 Sep 2019 15:53:48 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <5E358F4B-552C-4542-9655-E01C7B754F14@lca.pw> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: On 9/11/19 5:19 PM, Qian Cai wrote: > > The new config looks redundant and confusing. It looks to me more of a document update > in Documentation/dev-tools/kasan.txt to educate developers to select PAGE_OWNER and > DEBUG_PAGEALLOC if needed. Agreed. But if you want it fully automatic, how about something like this (on top of mmotm/next)? If you agree I'll add changelog and send properly. ----8<---- >From a528d14c71d7fdf5872ca8ab3bd1b5bad26670c9 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Thu, 12 Sep 2019 15:51:23 +0200 Subject: [PATCH] make KASAN enable page_owner with free stack capture --- include/linux/page_owner.h | 1 + lib/Kconfig.kasan | 4 ++++ mm/Kconfig.debug | 5 +++++ mm/page_alloc.c | 6 +++++- mm/page_owner.c | 37 ++++++++++++++++++++++++------------- 5 files changed, 39 insertions(+), 14 deletions(-) diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h index 8679ccd722e8..6ffe8b81ba85 100644 --- a/include/linux/page_owner.h +++ b/include/linux/page_owner.h @@ -6,6 +6,7 @@ #ifdef CONFIG_PAGE_OWNER extern struct static_key_false page_owner_inited; +extern bool page_owner_free_stack_disabled; extern struct page_ext_operations page_owner_ops; extern void __reset_page_owner(struct page *page, unsigned int order); diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 6c9682ce0254..dc560c7562e8 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -41,6 +41,8 @@ config KASAN_GENERIC select SLUB_DEBUG if SLUB select CONSTRUCTORS select STACKDEPOT + select PAGE_OWNER + select PAGE_OWNER_FREE_STACK help Enables generic KASAN mode. Supported in both GCC and Clang. With GCC it requires version 4.9.2 @@ -63,6 +65,8 @@ config KASAN_SW_TAGS select SLUB_DEBUG if SLUB select CONSTRUCTORS select STACKDEPOT + select PAGE_OWNER + select PAGE_OWNER_FREE_STACK help Enables software tag-based KASAN mode. This mode requires Top Byte Ignore support by the CPU and therefore diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 327b3ebf23bf..a71d52636687 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -13,6 +13,7 @@ config DEBUG_PAGEALLOC depends on DEBUG_KERNEL depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC + select PAGE_OWNER_FREE_STACK if PAGE_OWNER ---help--- Unmap pages from the kernel linear mapping after free_pages(). Depending on runtime enablement, this results in a small or large @@ -62,6 +63,10 @@ config PAGE_OWNER If unsure, say N. +config PAGE_OWNER_FREE_STACK + def_bool n + depends on PAGE_OWNER + config PAGE_POISONING bool "Poison pages after freeing" select PAGE_POISONING_NO_SANITY if HIBERNATION diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c5d62f1c2851..d9e44671af3f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -710,8 +710,12 @@ static int __init early_debug_pagealloc(char *buf) if (kstrtobool(buf, &enable)) return -EINVAL; - if (enable) + if (enable) { static_branch_enable(&_debug_pagealloc_enabled); +#ifdef CONFIG_PAGE_OWNER + page_owner_free_stack_disabled = false; +#endif + } return 0; } diff --git a/mm/page_owner.c b/mm/page_owner.c index dee931184788..d4551d7012d0 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -24,13 +24,15 @@ struct page_owner { short last_migrate_reason; gfp_t gfp_mask; depot_stack_handle_t handle; -#ifdef CONFIG_DEBUG_PAGEALLOC +#ifdef CONFIG_PAGE_OWNER_FREE_STACK depot_stack_handle_t free_handle; #endif }; static bool page_owner_disabled = true; +bool page_owner_free_stack_disabled = true; DEFINE_STATIC_KEY_FALSE(page_owner_inited); +static DEFINE_STATIC_KEY_FALSE(page_owner_free_stack); static depot_stack_handle_t dummy_handle; static depot_stack_handle_t failure_handle; @@ -46,6 +48,11 @@ static int __init early_page_owner_param(char *buf) if (strcmp(buf, "on") == 0) page_owner_disabled = false; + if (IS_ENABLED(CONFIG_KASAN)) { + page_owner_disabled = false; + page_owner_free_stack_disabled = false; + } + return 0; } early_param("page_owner", early_page_owner_param); @@ -91,6 +98,8 @@ static void init_page_owner(void) register_failure_stack(); register_early_stack(); static_branch_enable(&page_owner_inited); + if (!page_owner_free_stack_disabled) + static_branch_enable(&page_owner_free_stack); init_early_allocated_pages(); } @@ -148,11 +157,11 @@ void __reset_page_owner(struct page *page, unsigned int order) { int i; struct page_ext *page_ext; -#ifdef CONFIG_DEBUG_PAGEALLOC +#ifdef CONFIG_PAGE_OWNER_FREE_STACK depot_stack_handle_t handle = 0; struct page_owner *page_owner; - if (debug_pagealloc_enabled()) + if (static_branch_unlikely(&page_owner_free_stack)) handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); #endif @@ -161,8 +170,8 @@ void __reset_page_owner(struct page *page, unsigned int order) if (unlikely(!page_ext)) continue; __clear_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); -#ifdef CONFIG_DEBUG_PAGEALLOC - if (debug_pagealloc_enabled()) { +#ifdef CONFIG_PAGE_OWNER_FREE_STACK + if (static_branch_unlikely(&page_owner_free_stack)) { page_owner = get_page_owner(page_ext); page_owner->free_handle = handle; } @@ -451,14 +460,16 @@ void __dump_page_owner(struct page *page) stack_trace_print(entries, nr_entries, 0); } -#ifdef CONFIG_DEBUG_PAGEALLOC - handle = READ_ONCE(page_owner->free_handle); - if (!handle) { - pr_alert("page_owner free stack trace missing\n"); - } else { - nr_entries = stack_depot_fetch(handle, &entries); - pr_alert("page last free stack trace:\n"); - stack_trace_print(entries, nr_entries, 0); +#ifdef CONFIG_PAGE_OWNER_FREE_STACK + if (static_branch_unlikely(&page_owner_free_stack)) { + handle = READ_ONCE(page_owner->free_handle); + if (!handle) { + pr_alert("page_owner free stack trace missing\n"); + } else { + nr_entries = stack_depot_fetch(handle, &entries); + pr_alert("page last free stack trace:\n"); + stack_trace_print(entries, nr_entries, 0); + } } #endif -- 2.23.0