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Date:   Tue, 6 Sep 2022 09:53:31 +0200
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Subject: Re: linux-next: build failure after merge of the slab tree
To:     Stephen Rothwell <sfr@canb.auug.org.au>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>
Cc:     Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Marco Elver <elver@google.com>
References: <20220906165131.59f395a9@canb.auug.org.au>
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From:   Vlastimil Babka <vbabka@suse.cz>
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On 9/6/22 08:51, Stephen Rothwell wrote:
> Hi all,

Hi,

> After merging the slab tree, today's linux-next build (powerpc
> ppc64_defconfig) failed like this:
> 
> kernel/bpf/memalloc.c: In function 'bpf_mem_free':
> kernel/bpf/memalloc.c:613:33: error: implicit declaration of function '__ksize'; did you mean 'ksize'? [-Werror=implicit-function-declaration]
>    613 |         idx = bpf_mem_cache_idx(__ksize(ptr - LLIST_NODE_SZ));
>        |                                 ^~~~~~~
>        |                                 ksize

Could you use ksize() here? I'm guessing you picked __ksize() because 
kasan_unpoison_element() in mm/mempool.c did, but that's to avoid 
kasan_unpoison_range() in ksize() as this caller does it differently.
AFAICS your function doesn't handle kasan differently, so ksize() should 
be fine.

> Caused by commit
> 
>    8dfa9d554061 ("mm/slab_common: move declaration of __ksize() to mm/slab.h")
> 
> interacting with commit
> 
>    7c8199e24fa0 ("bpf: Introduce any context BPF specific memory allocator.")
> 
> from the bpf-next tree.
> 
> I have reverted the slab tree commit for today.
>