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Message-ID: <aaebf2a5-026b-54f8-3fad-8e9611732e5e@huawei.com>
Date:   Mon, 6 Jun 2022 09:34:13 +0800
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Subject: Re: [PATCH v2 1/3] mm/shmem: check return value of
 shmem_init_inodecache
To:     Matthew Wilcox <willy@infradead.org>
CC:     <hughd@google.com>, <akpm@linux-foundation.org>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <david@redhat.com>, <wangkefeng.wang@huawei.com>
References: <20220605035557.3957759-1-chenwandun@huawei.com>
 <20220605035557.3957759-2-chenwandun@huawei.com>
 <YpyYSFjTQQQ/p4bM@casper.infradead.org>
From:   Chen Wandun <chenwandun@huawei.com>
In-Reply-To: <YpyYSFjTQQQ/p4bM@casper.infradead.org>
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On 2022/6/5 19:49, Matthew Wilcox wrote:
> On Sun, Jun 05, 2022 at 11:55:55AM +0800, Chen Wandun wrote:
>> It will result in null pointer access if shmem_init_inodecache fail,
>> so check return value of shmem_init_inodecache
> You ignored my suggestion from v1.  Here, let me write it out for you.
Hi Matthew,
I didn't ignore your suggestion,  some explanation is needed, sorry for 
that.

In V1, Kefeng point:
"kmem_cache_create return a pointer to the cache on success, NULL on 
failure,
so error = -ENOMEM; is right :)"

so, I look some similar code such as init_inodecache in kinds of file 
system,  they all
return -ENOMEM on failure, so is it OK to return -ENOMEM on failure :)

Besides,  kmem_cache_create return NULL on failure, maybe returning 
error code
on failure is more proper, but it is another job.
>
> +static int shmem_init_inodecache(void)
>   {
>    	shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
>    				sizeof(struct shmem_inode_info),
>    				0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
> +	if (!shmem_inode_cachep)
> +		return -ENOMEM;
> +	return 0;
>   }
>
> ...
>
> +	error = shmem_init_inodecache();
> +	if (error)
> +		goto out2;
>
>
> .