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Thu, 12 Sep 2019 23:13:52 +0800 Message-ID: <1568301233.19274.17.camel@mtksdccf07> Subject: Re: [PATCH v3] mm/kasan: dump alloc and free stack for page allocator From: Walter Wu To: Vlastimil Babka Date: Thu, 12 Sep 2019 23:13:53 +0800 In-Reply-To: <613f9f23-c7f0-871f-fe13-930c35ef3105@suse.cz> References: <20190911083921.4158-1-walter-zh.wu@mediatek.com> <5E358F4B-552C-4542-9655-E01C7B754F14@lca.pw> <1568297308.19040.5.camel@mtksdccf07> <613f9f23-c7f0-871f-fe13-930c35ef3105@suse.cz> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190912_081402_242957_82C8ED98 X-CRM114-Status: GOOD ( 18.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Qian Cai , wsd_upstream@mediatek.com, Arnd Bergmann , linux-mm@kvack.org, Andrey Konovalov , linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Martin Schwidefsky , Alexander Potapenko , linux-arm-kernel@lists.infradead.org, Matthias Brugger , Andrey Ryabinin , Andrew Morton , Dmitry Vyukov Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 2019-09-12 at 16:31 +0200, Vlastimil Babka wrote: > On 9/12/19 4:08 PM, Walter Wu wrote: > > > >> 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 > > > > What is the difference between PAGE_OWNER+PAGE_OWNER_FREE_STACK and > > DEBUG_PAGEALLOC? > > Same memory usage, but debug_pagealloc means also extra checks and > restricting memory access to freed pages to catch UAF. > > > If you directly enable PAGE_OWNER+PAGE_OWNER_FREE_STACK > > PAGE_OWNER_FREE_STACK,don't you think low-memory device to want to use > > KASAN? > > OK, so it should be optional? But I think it's enough to distinguish no > PAGE_OWNER at all, and PAGE_OWNER+PAGE_OWNER_FREE_STACK together - I > don't see much point in PAGE_OWNER only for this kind of debugging. > If it's possible, it should be optional. My experience is that PAGE_OWNER usually debug memory leakage. > So how about this? KASAN wouldn't select PAGE_OWNER* but it would be > recommended in the help+docs. When PAGE_OWNER and KASAN are selected by > user, PAGE_OWNER_FREE_STACK gets also selected, and both will be also > runtime enabled without explicit page_owner=on. > I mostly want to avoid another boot-time option for enabling > PAGE_OWNER_FREE_STACK. > Would that be enough flexibility for low-memory devices vs full-fledged > debugging? We usually see feature option to decide whether it meet the platform. The boot-time option isn't troubled to us, because enable the feature owner should know what he should add to do. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel