Patchwork ext4: page_cache pages not released in ext4_mb_load_buddy()

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Submitter jing zhang
Date March 24, 2010, 2:21 p.m.
Message ID <ac8f92701003240721l7a7079dnd9cbd55526cd1788@mail.gmail.com>
Download mbox | patch
Permalink /patch/48418/
State New
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jing zhang - March 24, 2010, 2:21 p.m.
From: Jing Zhang <zj.barak@gmail.com>

Date: Wed Mar 24 20:38:48     2010

If ext4_mb_init_cache() returns error, there is no page_cache_release() issued.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Jing Zhang <zj.barak@gmail.com>

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Aneesh Kumar K.V - March 24, 2010, 4:49 p.m.
On Wed, 24 Mar 2010 22:21:01 +0800, jing zhang <zj.barak@gmail.com> wrote:
> From: Jing Zhang <zj.barak@gmail.com>
> 
> Date: Wed Mar 24 20:38:48     2010
> 
> If ext4_mb_init_cache() returns error, there is no page_cache_release() issued.
> 
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Andreas Dilger <adilger@sun.com>
> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
> Signed-off-by: Jing Zhang <zj.barak@gmail.com>
> 
> ---
> 
> --- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
> +++ ext4_mm_leak/mballoc-9.c	2010-03-24 22:24:56.000000000 +0800
> @@ -1132,8 +1132,6 @@ repeat_load_buddy:
>  	e4b->bd_buddy = page_address(page) + (poff * sb->s_blocksize);
>  	mark_page_accessed(page);
> 
> -	BUG_ON(e4b->bd_bitmap_page == NULL);
> -	BUG_ON(e4b->bd_buddy_page == NULL);

Why remove these ? 

> 
>  	return 0;
> 
> @@ -1142,6 +1140,8 @@ err:
>  		page_cache_release(e4b->bd_bitmap_page);
>  	if (e4b->bd_buddy_page)
>  		page_cache_release(e4b->bd_buddy_page);
> +	if (page)
> +		page_cache_release(page);
>  	e4b->bd_buddy = NULL;
>  	e4b->bd_bitmap = NULL;

Can you add a comment which says on error page will point to the page
cache page which haven't been assigned to neither bd_bitmap_page or
bd_buddy_page

But good catch !!

-aneesh
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jing zhang - March 25, 2010, 2:02 p.m.
2010/3/25, Aneesh Kumar K. V <aneesh.kumar@linux.vnet.ibm.com>:
> On Wed, 24 Mar 2010 22:21:01 +0800, jing zhang <zj.barak@gmail.com> wrote:
>> From: Jing Zhang <zj.barak@gmail.com>
>>
>> Date: Wed Mar 24 20:38:48     2010
>>
>> If ext4_mb_init_cache() returns error, there is no page_cache_release()
>> issued.
>>
>> Cc: Theodore Ts'o <tytso@mit.edu>
>> Cc: Andreas Dilger <adilger@sun.com>
>> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
>> Signed-off-by: Jing Zhang <zj.barak@gmail.com>
>>
>> ---
>>
>> --- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
>> +++ ext4_mm_leak/mballoc-9.c	2010-03-24 22:24:56.000000000 +0800
>> @@ -1132,8 +1132,6 @@ repeat_load_buddy:
>>  	e4b->bd_buddy = page_address(page) + (poff * sb->s_blocksize);
>>  	mark_page_accessed(page);
>>
>> -	BUG_ON(e4b->bd_bitmap_page == NULL);
>> -	BUG_ON(e4b->bd_buddy_page == NULL);
>
> Why remove these ?

Just before return successfully, both bitmap page and buddy page are assigned.
If not either, EIO will branch.

>
>>
>>  	return 0;
>>
>> @@ -1142,6 +1140,8 @@ err:
>>  		page_cache_release(e4b->bd_bitmap_page);
>>  	if (e4b->bd_buddy_page)
>>  		page_cache_release(e4b->bd_buddy_page);
>> +	if (page)
>> +		page_cache_release(page);
>>  	e4b->bd_buddy = NULL;
>>  	e4b->bd_bitmap = NULL;
>
> Can you add a comment which says on error page will point to the page
> cache page which haven't been assigned to neither bd_bitmap_page or
> bd_buddy_page

+	if (page)
+            /* we have to release page here in case that
+             * ext4_mb_init_cache() returns error when preparing
+             * either bitmap_ or buddy_page.
+             */
+		page_cache_release(page);

>
> But good catch !!
>
> -aneesh
>

Is that ok, Aneesh?

        - zj
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Aneesh Kumar K.V - March 26, 2010, 8:04 a.m.
On Thu, 25 Mar 2010 22:02:44 +0800, jing zhang <zj.barak@gmail.com> wrote:
> 2010/3/25, Aneesh Kumar K. V <aneesh.kumar@linux.vnet.ibm.com>:
> > On Wed, 24 Mar 2010 22:21:01 +0800, jing zhang <zj.barak@gmail.com> wrote:
> >> From: Jing Zhang <zj.barak@gmail.com>
> >>
> >> Date: Wed Mar 24 20:38:48     2010
> >>
> >> If ext4_mb_init_cache() returns error, there is no page_cache_release()
> >> issued.
> >>
> >> Cc: Theodore Ts'o <tytso@mit.edu>
> >> Cc: Andreas Dilger <adilger@sun.com>
> >> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
> >> Signed-off-by: Jing Zhang <zj.barak@gmail.com>
> >>
> >> ---
> >>
> >> --- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
> >> +++ ext4_mm_leak/mballoc-9.c	2010-03-24 22:24:56.000000000 +0800
> >> @@ -1132,8 +1132,6 @@ repeat_load_buddy:
> >>  	e4b->bd_buddy = page_address(page) + (poff * sb->s_blocksize);
> >>  	mark_page_accessed(page);
> >>
> >> -	BUG_ON(e4b->bd_bitmap_page == NULL);
> >> -	BUG_ON(e4b->bd_buddy_page == NULL);
> >
> > Why remove these ?
> 
> Just before return successfully, both bitmap page and buddy page are assigned.
> If not either, EIO will branch.
> 
> >
> >>
> >>  	return 0;
> >>
> >> @@ -1142,6 +1140,8 @@ err:
> >>  		page_cache_release(e4b->bd_bitmap_page);
> >>  	if (e4b->bd_buddy_page)
> >>  		page_cache_release(e4b->bd_buddy_page);
> >> +	if (page)
> >> +		page_cache_release(page);
> >>  	e4b->bd_buddy = NULL;
> >>  	e4b->bd_bitmap = NULL;
> >
> > Can you add a comment which says on error page will point to the page
> > cache page which haven't been assigned to neither bd_bitmap_page or
> > bd_buddy_page
> 
> +	if (page)
> +            /* we have to release page here in case that
> +             * ext4_mb_init_cache() returns error when preparing
> +             * either bitmap_ or buddy_page.
> +             */
> +		page_cache_release(page);
> 
> >
> > But good catch !!
> >
> > -aneesh
> >
> 
> Is that ok, Aneesh?

looks good

-aneesh
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Patch

--- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
+++ ext4_mm_leak/mballoc-9.c	2010-03-24 22:24:56.000000000 +0800
@@ -1132,8 +1132,6 @@  repeat_load_buddy:
 	e4b->bd_buddy = page_address(page) + (poff * sb->s_blocksize);
 	mark_page_accessed(page);

-	BUG_ON(e4b->bd_bitmap_page == NULL);
-	BUG_ON(e4b->bd_buddy_page == NULL);

 	return 0;

@@ -1142,6 +1140,8 @@  err:
 		page_cache_release(e4b->bd_bitmap_page);
 	if (e4b->bd_buddy_page)
 		page_cache_release(e4b->bd_buddy_page);
+	if (page)
+		page_cache_release(page);
 	e4b->bd_buddy = NULL;
 	e4b->bd_bitmap = NULL;
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