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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 36326C432C2 for ; Thu, 26 Sep 2019 09:16:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0814217F4 for ; Thu, 26 Sep 2019 09:16:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="mSJPHGU/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730283AbfIZJQE (ORCPT ); Thu, 26 Sep 2019 05:16:04 -0400 Received: from mail-ed1-f65.google.com ([209.85.208.65]:34537 "EHLO mail-ed1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728129AbfIZJQD (ORCPT ); Thu, 26 Sep 2019 05:16:03 -0400 Received: by mail-ed1-f65.google.com with SMTP id p10so1320330edq.1 for ; Thu, 26 Sep 2019 02:16:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=C50uCIRZXB+UBz8ksrHz9YHG9QxeChHhVCa2axN7YVA=; b=mSJPHGU/Ii+qAyY9nTYzRFKSjkSgZt6UkVNixHRAHp1jNX3v/0QS78MRlpljP3iJi+ SDIqvf6Wn0OgQC+/GARBKIi3QYM3XIDXSqGe1pM4k4T7nKELUuJeYBdKCiQI1kWeQcgH gfrbuiziptUfyaZIGLK6MZNAxcP3V6g/AybE4oiJtZggPIKHtCa4RizDg6P9BOGIhQU6 AXlY1MuMM/Ui4aEPbgx3ea7J8cGIicX9itpZxSUjTYHeFaN/hxr2Yx61+hIZeJ5legVF kc34oxQhXIyJPMZEOk5ybbP6dLn6aVo5aFZeZxkoaqeJtmI/SrGYWeNLAeLJXPojQDeF KLtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=C50uCIRZXB+UBz8ksrHz9YHG9QxeChHhVCa2axN7YVA=; b=gSmMs7HYusW/NLS2SxF39K9boVDQX0o8wOZNiQYdXhbNqb1O1gNSrnTUnTQdYYcy3+ lnc72ItN3UEdOFflLX8hS+9iXbKjKSAj2mEayww8H4i3TjzSBRZhhMtshdnTw4Gz9HNV JeYHdEZTKOWTPjpiEjVkXNq6N46GnTl3RmdXu/N//CsV3y/dUkxs38ISnjYIw0/62V2s LUKTUfBlK9tt3riry2VvlX2lhVWSiUXTddBOSYuXfM1dfRqKYsgWVZmX732hp3inmSPo Z/j65KGK008BywDJrCDu8j6NLr43k070YR51qRa2cekRHnGzAG+RKWWJX/cz19SsmP8y XbgQ== X-Gm-Message-State: APjAAAW978G0CJR9Pl4mWBHaLlqfNdS+/fi2CrjTI8Zf6oQ6SkIpOukE r/UlhUAOVPBaIehguz8Tjzr5vQ== X-Google-Smtp-Source: APXvYqyqkf1tIwLWoAatOKH01Tl0xCiTI1zaafbU9IHBWlAXKRm98sUt/8DWULgxHHYfuiRGLBjntQ== X-Received: by 2002:a50:ac03:: with SMTP id v3mr2407789edc.113.1569489361850; Thu, 26 Sep 2019 02:16:01 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id o31sm352089edd.17.2019.09.26.02.16.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Sep 2019 02:16:01 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 105B1102322; Thu, 26 Sep 2019 12:16:04 +0300 (+03) Date: Thu, 26 Sep 2019 12:16:04 +0300 From: "Kirill A. Shutemov" To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Qian Cai , "Kirill A. Shutemov" , Matthew Wilcox , Mel Gorman , Michal Hocko , Dmitry Vyukov , Walter Wu , Andrey Ryabinin Subject: Re: [PATCH 2/3] mm, debug, kasan: save and dump freeing stack trace for kasan Message-ID: <20190926091604.axt7uqmds6sd3bnu@box> References: <20190925143056.25853-1-vbabka@suse.cz> <20190925143056.25853-3-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190925143056.25853-3-vbabka@suse.cz> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 25, 2019 at 04:30:51PM +0200, Vlastimil Babka wrote: > The commit 8974558f49a6 ("mm, page_owner, debug_pagealloc: save and dump > freeing stack trace") enhanced page_owner to also store freeing stack trace, > when debug_pagealloc is also enabled. KASAN would also like to do this [1] to > improve error reports to debug e.g. UAF issues. This patch therefore introduces > a helper config option PAGE_OWNER_FREE_STACK, which is enabled when PAGE_OWNER > and either of DEBUG_PAGEALLOC or KASAN is enabled. Boot-time, the free stack > saving is enabled when booting a KASAN kernel with page_owner=on, or non-KASAN > kernel with debug_pagealloc=on and page_owner=on. I would like to have an option to enable free stack for any PAGE_OWNER user at boot-time. Maybe drop CONFIG_PAGE_OWNER_FREE_STACK completely and add page_owner_free=on cmdline option as yet another way to trigger 'static_branch_enable(&page_owner_free_stack)'? > [1] https://bugzilla.kernel.org/show_bug.cgi?id=203967 > > Suggested-by: Dmitry Vyukov > Suggested-by: Walter Wu > Suggested-by: Andrey Ryabinin > Signed-off-by: Vlastimil Babka > Reviewed-by: Andrey Ryabinin > --- > Documentation/dev-tools/kasan.rst | 4 ++++ > mm/Kconfig.debug | 4 ++++ > mm/page_owner.c | 31 ++++++++++++++++++------------- > 3 files changed, 26 insertions(+), 13 deletions(-) > > diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst > index b72d07d70239..434e605030e9 100644 > --- a/Documentation/dev-tools/kasan.rst > +++ b/Documentation/dev-tools/kasan.rst > @@ -41,6 +41,10 @@ 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. > > +To augment reports with last allocation and freeing stack of the physical > +page, it is recommended to configure kernel also with CONFIG_PAGE_OWNER = y Nit: remove spaces around '=' or write "with CONFIG_PAGE_OWNER enabled". > +and boot with page_owner=on. > + > To disable instrumentation for specific files or directories, add a line > similar to the following to the respective kernel Makefile: > > diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug > index 327b3ebf23bf..1ea247da3322 100644 > --- a/mm/Kconfig.debug > +++ b/mm/Kconfig.debug > @@ -62,6 +62,10 @@ config PAGE_OWNER > > If unsure, say N. > > +config PAGE_OWNER_FREE_STACK > + def_bool KASAN || DEBUG_PAGEALLOC > + depends on PAGE_OWNER > + > config PAGE_POISONING > bool "Poison pages after freeing" > select PAGE_POISONING_NO_SANITY if HIBERNATION > diff --git a/mm/page_owner.c b/mm/page_owner.c > index d3cf5d336ccf..f3aeec78822f 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -24,13 +24,14 @@ 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; > 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; > @@ -91,6 +92,8 @@ static void init_page_owner(void) > register_failure_stack(); > register_early_stack(); > static_branch_enable(&page_owner_inited); > + if (IS_ENABLED(CONFIG_KASAN) || debug_pagealloc_enabled()) > + static_branch_enable(&page_owner_free_stack); > init_early_allocated_pages(); > } > > @@ -148,11 +151,11 @@ 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 +164,8 @@ void __reset_page_owner(struct page *page, unsigned int order) > return; > for (i = 0; i < (1 << order); i++) { > __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; > } > @@ -450,14 +453,16 @@ 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 > > -- Kirill A. Shutemov