From: Walter Wu <walter-zh.wu@mediatek.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Qian Cai <cai@lca.pw>, Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Andrey Konovalov <andreyknvl@google.com>,
"Arnd Bergmann" <arnd@arndb.de>, <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>
Subject: Re: [PATCH v3] mm/kasan: dump alloc and free stack for page allocator
Date: Thu, 12 Sep 2019 23:13:53 +0800 [thread overview]
Message-ID: <1568301233.19274.17.camel@mtksdccf07> (raw)
In-Reply-To: <613f9f23-c7f0-871f-fe13-930c35ef3105@suse.cz>
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.
next prev parent reply other threads:[~2019-09-12 15:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 8:39 [PATCH v3] mm/kasan: dump alloc and free stack for page allocator Walter Wu
2019-09-11 15:19 ` Qian Cai
2019-09-12 13:53 ` Vlastimil Babka
2019-09-12 14:08 ` Andrey Ryabinin
2019-09-12 14:08 ` Walter Wu
2019-09-12 14:31 ` Vlastimil Babka
2019-09-12 15:13 ` Walter Wu [this message]
2019-09-12 17:05 ` Andrey Ryabinin
2019-09-16 9:42 ` Vlastimil Babka
2019-09-16 15:57 ` Andrey Ryabinin
2019-09-17 8:19 ` Vlastimil Babka
2019-09-23 8:20 ` [PATCH] mm, debug, kasan: save and dump freeing stack trace for kasan Vlastimil Babka
2019-09-25 9:41 ` Andrey Ryabinin
2019-09-12 14:10 ` [PATCH v3] mm/kasan: dump alloc and free stack for page allocator Qian Cai
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