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Date:   Tue, 1 Jun 2021 17:26:59 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     kernel test robot <lkp@intel.com>
Cc:     Stephen Boyd <swboyd@chromium.org>, kbuild-all@lists.01.org,
        clang-built-linux@googlegroups.com,
        Linux Memory Management List <linux-mm@kvack.org>,
        linux-kernel@vger.kernel.org,
        Christoph Lameter <cl@linux-foundation.org>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Petr Mladek <pmladek@suse.com>, Joe Perches <joe@perches.com>
Subject: Re: [PATCH v3 4/4] slub: Force on no_hash_pointers when slub_debug
 is enabled
Message-Id: <20210601172659.fd8c40a6548a1bd43be1bf11@linux-foundation.org>
In-Reply-To: <202106020644.UDFIJOUU-lkp@intel.com>
References: <20210601182202.3011020-5-swboyd@chromium.org>
        <202106020644.UDFIJOUU-lkp@intel.com>
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On Wed, 2 Jun 2021 06:45:55 +0800 kernel test robot <lkp@intel.com> wrote:

> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
>            if (static_branch_unlikely(&slub_debug_enabled))
>                                        ^
> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
> >> mm/slub.c:4464:6: error: invalid argument type 'void' to unary expression
>            if (static_branch_unlikely(&slub_debug_enabled))
>                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thanks.  Stephen, how about this?

--- a/mm/slub.c~slub-force-on-no_hash_pointers-when-slub_debug-is-enabled-fix
+++ a/mm/slub.c
@@ -117,12 +117,26 @@
  */
 
 #ifdef CONFIG_SLUB_DEBUG
+
 #ifdef CONFIG_SLUB_DEBUG_ON
 DEFINE_STATIC_KEY_TRUE(slub_debug_enabled);
 #else
 DEFINE_STATIC_KEY_FALSE(slub_debug_enabled);
 #endif
-#endif
+
+static inline bool __slub_debug_enabled(void)
+{
+	return static_branch_unlikely(&slub_debug_enabled);
+}
+
+#else		/* CONFIG_SLUB_DEBUG */
+
+static inline bool __slub_debug_enabled(void)
+{
+	return false;
+}
+
+#endif		/* CONFIG_SLUB_DEBUG */
 
 static inline bool kmem_cache_debug(struct kmem_cache *s)
 {
@@ -4493,7 +4507,7 @@ void __init kmem_cache_init(void)
 		slub_max_order = 0;
 
 	/* Print slub debugging pointers without hashing */
-	if (static_branch_unlikely(&slub_debug_enabled))
+	if (__slub_debug_enabled())
 		no_hash_pointers_enable(NULL);
 
 	kmem_cache_node = &boot_kmem_cache_node;
_