linux-ext4 - Re: [PATCH] ext4: memory leakage in ext4_mb_free

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Message-ID: <87d3ytd56l.fsf@linux.vnet.ibm.com>
Date:	Wed, 24 Mar 2010 22:31:54 +0530
From:	"Aneesh Kumar K. V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	jing zhang <zj.barak@...il.com>,
	linux-ext4 <linux-ext4@...r.kernel.org>
Cc:	"Theodore Ts'o" <tytso@....edu>, Andreas Dilger <adilger@....com>,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Subject: Re: [PATCH] ext4: memory leakage in ext4_mb_free_blocks()

On Wed, 24 Mar 2010 21:55:55 +0800, jing zhang <zj.barak@...il.com> wrote:
> From: Jing Zhang <zj.barak@...il.com>
> 
> Date: Wed Mar 24 21:54:22     2010
> 
> There is memory leakage in ext4_mb_free_blocks(), if error, double
> free of blocks, occurs in ext4_mb_free_metadata().
> 
> Cc: Theodore Ts'o <tytso@....edu>
> Cc: Andreas Dilger <adilger@....com>
> Cc: Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
> Signed-off-by: Jing Zhang <zj.barak@...il.com>
> 
> ---
> 
> --- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
> +++ ext4_mm_leak/mballoc8.c	2010-03-24 21:46:50.000000000 +0800
> @@ -4419,7 +4419,8 @@ ext4_mb_free_metadata(handle_t *handle,
>  	spin_lock(&sbi->s_md_lock);
>  	list_add(&new_entry->list, &handle->h_transaction->t_private_list);
>  	spin_unlock(&sbi->s_md_lock);
> -	return 0;
> +	/* info the caller new_entry is used */
> +	return 1;
>  }
> 

return 0 on success and -1 on failure 


>  /*
> @@ -4547,7 +4548,8 @@ do_more:
> 
>  		ext4_lock_group(sb, block_group);
>  		mb_clear_bits(bitmap_bh->b_data, bit, count);
> -		ext4_mb_free_metadata(handle, &e4b, new_entry);
> +		if (0 == ext4_mb_free_metadata(handle, &e4b, new_entry))
> +			kmem_cache_free(ext4_free_ext_cachep,
>  		new_entry);

I guess  it would be better to be 

if (ext4_mb_free_metadat() == -1)
   kmem_cache_free(..)



>  	} else {
>  		/* need to update group_info->bb_free and bitmap
>  		 * with group lock held. generate_buddy look at


-aneesh
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