Re: [f2fs-dev] [PATCH] f2fs: don't return vmalloc() memory from f2fs_kmalloc()

[Chao Yu <yuchao0@huawei.com>]

On 2020/5/6 4:48, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> kmalloc() returns kmalloc'ed memory, and kvmalloc() returns either
> kmalloc'ed or vmalloc'ed memory.  But the f2fs wrappers, f2fs_kmalloc()
> and f2fs_kvmalloc(), both return both kinds of memory.
> 
> It's redundant to have two functions that do the same thing, and also
> breaking the standard naming convention is causing bugs since people
> assume it's safe to kfree() memory allocated by f2fs_kmalloc().  See
> e.g. the various allocations in fs/f2fs/compress.c.
> 
> Fix this by making f2fs_kmalloc() just use kmalloc().  And to avoid
> re-introducing the allocation failures that the vmalloc fallback was
> intended to fix, convert the largest allocations to use f2fs_kvmalloc().

I've submitted one patch since you suggested when commented in compression
support patch.

I remember Jaegeuk prefer to use f2fs_kvmalloc() to instead f2fs_kmalloc(),
and keep the order of kmalloc - failed - kvmalloc.

Thanks,

> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>  fs/f2fs/checkpoint.c | 4 ++--
>  fs/f2fs/f2fs.h       | 8 +-------
>  fs/f2fs/node.c       | 8 ++++----
>  3 files changed, 7 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 97b6378554b406..ac5b47f15f5e77 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -895,8 +895,8 @@ int f2fs_get_valid_checkpoint(struct f2fs_sb_info *sbi)
>  	int i;
>  	int err;
>  
> -	sbi->ckpt = f2fs_kzalloc(sbi, array_size(blk_size, cp_blks),
> -				 GFP_KERNEL);
> +	sbi->ckpt = f2fs_kvzalloc(sbi, array_size(blk_size, cp_blks),
> +				  GFP_KERNEL);
>  	if (!sbi->ckpt)
>  		return -ENOMEM;
>  	/*
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index d036a31a97e84e..bc4c5b9b1bf14c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2953,18 +2953,12 @@ static inline bool f2fs_may_extent_tree(struct inode *inode)
>  static inline void *f2fs_kmalloc(struct f2fs_sb_info *sbi,
>  					size_t size, gfp_t flags)
>  {
> -	void *ret;
> -
>  	if (time_to_inject(sbi, FAULT_KMALLOC)) {
>  		f2fs_show_injection_info(sbi, FAULT_KMALLOC);
>  		return NULL;
>  	}
>  
> -	ret = kmalloc(size, flags);
> -	if (ret)
> -		return ret;
> -
> -	return kvmalloc(size, flags);
> +	return kmalloc(size, flags);
>  }
>  
>  static inline void *f2fs_kzalloc(struct f2fs_sb_info *sbi,
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 4da0d8713df5cb..e660af55565c61 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -2934,7 +2934,7 @@ static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
>  		return 0;
>  
>  	nm_i->nat_bits_blocks = F2FS_BLK_ALIGN((nat_bits_bytes << 1) + 8);
> -	nm_i->nat_bits = f2fs_kzalloc(sbi,
> +	nm_i->nat_bits = f2fs_kvzalloc(sbi,
>  			nm_i->nat_bits_blocks << F2FS_BLKSIZE_BITS, GFP_KERNEL);
>  	if (!nm_i->nat_bits)
>  		return -ENOMEM;
> @@ -3067,9 +3067,9 @@ static int init_free_nid_cache(struct f2fs_sb_info *sbi)
>  	int i;
>  
>  	nm_i->free_nid_bitmap =
> -		f2fs_kzalloc(sbi, array_size(sizeof(unsigned char *),
> -					     nm_i->nat_blocks),
> -			     GFP_KERNEL);
> +		f2fs_kvzalloc(sbi, array_size(sizeof(unsigned char *),
> +					      nm_i->nat_blocks),
> +			      GFP_KERNEL);
>  	if (!nm_i->free_nid_bitmap)
>  		return -ENOMEM;
>  
> 


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