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Mon, 12 Sep 2022 00:18:08 -0700 (PDT) Date: Mon, 12 Sep 2022 16:18:03 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Ben Luo Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/slub: return 0 when object pointer is NULL Message-ID: References: <1662962379-16174-1-git-send-email-luoben@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1662962379-16174-1-git-send-email-luoben@linux.alibaba.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662967090; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FWAgKNPfCinc6qD4niSWvgkzCEX7z6+nrY4Z/gZWqPw=; 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dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam06 X-Stat-Signature: wai8thnozyazszad7g7y6j65ip86tqdy X-Rspamd-Queue-Id: A04244008E X-HE-Tag: 1662967090-141390 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Sep 12, 2022 at 01:59:39PM +0800, Ben Luo wrote: > NULL is definitly not a valid address > > Signed-off-by: Ben Luo > --- > mm/slub.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 862dbd9..50fad18 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -674,7 +674,7 @@ static inline int check_valid_pointer(struct kmem_cache *s, > void *base; > > if (!object) > - return 1; > + return 0; > > base = slab_address(slab); > object = kasan_reset_tag(object); > -- > 1.8.3.1 > Hello Ben. The return value is used to check if the @object has valid pointer in @slab. (used for debugging) the return value is 0 if valid, 1 if invalid. It does not return a pointer. So changing it to 0 because 1 is invalid address does not make sense. -- Thanks, Hyeonggon