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Message-ID: <14bd73b0-5480-2b35-7b89-161075d9f444@suse.cz>
Date:   Fri, 25 Nov 2022 08:50:35 +0100
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Subject: Re: linux-next: build failure after merge of the slab tree
To:     Stephen Rothwell <sfr@canb.auug.org.au>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Marco Elver <elver@google.com>,
        kasan-dev <kasan-dev@googlegroups.com>
References: <20221125124934.462dc661@canb.auug.org.au>
Content-Language: en-US
From:   Vlastimil Babka <vbabka@suse.cz>
In-Reply-To: <20221125124934.462dc661@canb.auug.org.au>
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On 11/25/22 02:49, Stephen Rothwell wrote:
> Hi all,
> 
> After merging the slab tree, today's linux-next build (x86_64
> allmodconfig) failed like this:
> 
> mm/slub.c:965:13: error: 'freelist_corrupted' defined but not used [-Werror=unused-function]
>   965 | static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
>       |             ^~~~~~~~~~~~~~~~~~
> 
> Caused by commit
> 
>   f6e94ad44e77 ("mm, slub: remove percpu slabs with CONFIG_SLUB_TINY")
> 
> I have used the slab tree from next-20221123 again.

I tried the allmodconfig and:

WARNING: unmet direct dependencies detected for SLUB_DEBUG
  Depends on [n]: SLUB [=y] && SYSFS [=y] && !SLUB_TINY [=y]
  Selected by [y]:
  - KASAN_GENERIC [=y] && <choice> && HAVE_ARCH_KASAN [=y] && CC_HAS_KASAN_GENERIC [=y] && CC_HAS_WORKING_NOSANITIZE_ADDRESS [=y] && SLUB [=y]

Wasn't aware it's possible that it will leave a combination of configs
that's not allowed and just warn about it. Oh well.

I'll solve it by:
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -37,7 +37,7 @@ menuconfig KASAN
                     (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \
                    CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \
                   HAVE_ARCH_KASAN_HW_TAGS
-       depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
+       depends on (SLUB && SYSFS && !SLUB_TINY) || (SLAB && !DEBUG_SLAB)
        select STACKDEPOT_ALWAYS_INIT
        help
          Enables KASAN (Kernel Address Sanitizer) - a dynamic memory safety