Re: [PATCH] mm/shmem: use kmem_cache_zalloc in shmem_alloc_inode()

[Vlastimil Babka]

On 11/15/20 6:40 PM, Hui Su wrote:
in shmem_get_inode():
new_inode();
   new_inode_pseudo();
     alloc_inode();
       ops->alloc_inode(); -> shmem_alloc_inode()
         kmem_cache_alloc();
memset(info, 0, (char *)inode - (char *)info);

So use kmem_cache_zalloc() in shmem_alloc_inode(),
and remove the memset in shmem_get_inode().

Signed-off-by: Hui Su <sh_...@163.com>

Looks correct, but now we clear also the inode part which seems to be handled by 
alloc_inode() well enough. So, unsure. btrfs and ext4 variants don't use kzalloc 
neither. It's also more obvious with the current way that the info is cleared. Hmm?

---
  mm/shmem.c | 3 +--
  1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 537c137698f8..b84adda45461 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2308,7 +2308,6 @@ static struct inode *shmem_get_inode(struct super_block 
*sb, const struct inode
                inode->i_atime = inode->i_mtime = inode->i_ctime = 
current_time(inode);
                inode->i_generation = prandom_u32();
                info = SHMEM_I(inode);
-               memset(info, 0, (char *)inode - (char *)info);
                spin_lock_init(&info->lock);
                atomic_set(&info->stop_eviction, 0);
                info->seals = F_SEAL_SEAL;
@@ -3828,7 +3827,7 @@ static struct kmem_cache *shmem_inode_cachep;
  static struct inode *shmem_alloc_inode(struct super_block *sb)
  {
        struct shmem_inode_info *info;
-       info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
+       info = kmem_cache_zalloc(shmem_inode_cachep, GFP_KERNEL);
        if (!info)
                return NULL;
        return &info->vfs_inode;