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Date:   Wed, 22 Nov 2023 18:13:23 +0100
From:   Marco Elver <elver@google.com>
To:     andrey.konovalov@linux.dev
Cc:     Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev@googlegroups.com, Evgenii Stepanov <eugenis@google.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
Subject: Re: [PATCH RFC 00/20] kasan: save mempool stack traces
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On Mon, Nov 06, 2023 at 09:10PM +0100, andrey.konovalov@linux.dev wrote:
> From: Andrey Konovalov <andreyknvl@google.com>
> 
> This series updates KASAN to save alloc and free stack traces for
> secondary-level allocators that cache and reuse allocations internally
> instead of giving them back to the underlying allocator (e.g. mempool).

Nice.

> As a part of this change, introduce and document a set of KASAN hooks:
> 
> bool kasan_mempool_poison_pages(struct page *page, unsigned int order);
> void kasan_mempool_unpoison_pages(struct page *page, unsigned int order);
> bool kasan_mempool_poison_object(void *ptr);
> void kasan_mempool_unpoison_object(void *ptr, size_t size);
> 
> and use them in the mempool code.
> 
> Besides mempool, skbuff and io_uring also cache allocations and already
> use KASAN hooks to poison those. Their code is updated to use the new
> mempool hooks.
>
> The new hooks save alloc and free stack traces (for normal kmalloc and
> slab objects; stack traces for large kmalloc objects and page_alloc are
> not supported by KASAN yet), improve the readability of the users' code,
> and also allow the users to prevent double-free and invalid-free bugs;
> see the patches for the details.
> 
> I'm posting this series as an RFC, as it has a few non-trivial-to-resolve
> conflicts with the stack depot eviction patches. I'll rebase the series and
> resolve the conflicts once the stack depot patches are in the mm tree.
> 
> Andrey Konovalov (20):
>   kasan: rename kasan_slab_free_mempool to kasan_mempool_poison_object
>   kasan: move kasan_mempool_poison_object
>   kasan: document kasan_mempool_poison_object
>   kasan: add return value for kasan_mempool_poison_object
>   kasan: introduce kasan_mempool_unpoison_object
>   kasan: introduce kasan_mempool_poison_pages
>   kasan: introduce kasan_mempool_unpoison_pages
>   kasan: clean up __kasan_mempool_poison_object
>   kasan: save free stack traces for slab mempools
>   kasan: clean up and rename ____kasan_kmalloc
>   kasan: introduce poison_kmalloc_large_redzone
>   kasan: save alloc stack traces for mempool
>   mempool: use new mempool KASAN hooks
>   mempool: introduce mempool_use_prealloc_only
>   kasan: add mempool tests
>   kasan: rename pagealloc tests
>   kasan: reorder tests
>   kasan: rename and document kasan_(un)poison_object_data
>   skbuff: use mempool KASAN hooks
>   io_uring: use mempool KASAN hook
> 
>  include/linux/kasan.h   | 161 +++++++-
>  include/linux/mempool.h |   2 +
>  io_uring/alloc_cache.h  |   5 +-
>  mm/kasan/common.c       | 221 ++++++----
>  mm/kasan/kasan_test.c   | 876 +++++++++++++++++++++++++++-------------
>  mm/mempool.c            |  49 ++-
>  mm/slab.c               |  10 +-
>  mm/slub.c               |   4 +-
>  net/core/skbuff.c       |  10 +-
>  9 files changed, 940 insertions(+), 398 deletions(-)

Overall LGTM and the majority of it is cleanups, so I think once the
stack depot patches are in the mm tree, just send v1 of this series.