Re: [PATCH v2 1/3] mm/shmem: check return value of shmem_init_inodecache

From: Chen Wandun
Date: Sun Jun 05 2022 - 21:34:21 EST




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;


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