[Patch] mm/sparse.c: Check the return value of sparse_index_alloc().

[Patch] mm/sparse.c: Check the return value of sparse_index_alloc().

[WANG Cong]

Since sparse_index_alloc() can return NULL on memory allocation failure,
we must deal with the failure condition when calling it.

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Rik van Riel <riel@redhat.com>

---

diff --git a/Makefile b/Makefile
diff --git a/mm/sparse.c b/mm/sparse.c
index e06f514..d245e59 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -83,6 +83,8 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
 		return -EEXIST;
 
 	section = sparse_index_alloc(nid);
+	if (!section)
+		return -ENOMEM;
 	/*
 	 * This lock keeps two different sections from
 	 * reallocating for the same index

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Re: [Patch] mm/sparse.c: Check the return value of sparse_index_alloc().

[Andrew Morton]

On Thu, 15 Nov 2007 21:54:28 +0800
WANG Cong <xiyou.wangcong@gmail.com> wrote:

> 
> Since sparse_index_alloc() can return NULL on memory allocation failure,
> we must deal with the failure condition when calling it.
> 
> Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: Rik van Riel <riel@redhat.com>
> 
> ---
> 
> diff --git a/Makefile b/Makefile
> diff --git a/mm/sparse.c b/mm/sparse.c
> index e06f514..d245e59 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -83,6 +83,8 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
>  		return -EEXIST;
>  
>  	section = sparse_index_alloc(nid);
> +	if (!section)
> +		return -ENOMEM;
>  	/*
>  	 * This lock keeps two different sections from
>  	 * reallocating for the same index

Sure, but both callers of sparse_index_init() ignore its return value anyway.

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Re: [Patch] mm/sparse.c: Check the return value of sparse_index_alloc().

[Dave Hansen]

On Thu, 2007-11-15 at 21:54 +0800, WANG Cong wrote:
> Since sparse_index_alloc() can return NULL on memory allocation failure,
> we must deal with the failure condition when calling it.
> 
> Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: Rik van Riel <riel@redhat.com>
> 
> ---
> 
> diff --git a/Makefile b/Makefile
> diff --git a/mm/sparse.c b/mm/sparse.c
> index e06f514..d245e59 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -83,6 +83,8 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
>  		return -EEXIST;
> 
>  	section = sparse_index_alloc(nid);
> +	if (!section)
> +		return -ENOMEM;
>  	/*
>  	 * This lock keeps two different sections from
>  	 * reallocating for the same index

Oddly enough, sparse_add_one_section() doesn't seem to like to check
its allocations.  The usemap is checked, but not freed on error.  If you
want to fix this up, I think it needs a little more love than just two
lines.  

Do you want to try to add some actual error handling to
sparse_add_one_section()?

-- Dave

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Re: [Patch] mm/sparse.c: Check the return value of sparse_index_alloc().

[WANG Cong]

On Mon, Nov 19, 2007 at 01:17:02PM -0800, Dave Hansen wrote:
>On Thu, 2007-11-15 at 21:54 +0800, WANG Cong wrote:
>> Since sparse_index_alloc() can return NULL on memory allocation failure,
>> we must deal with the failure condition when calling it.
>> 
>> Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
>> Cc: Christoph Lameter <clameter@sgi.com>
>> Cc: Rik van Riel <riel@redhat.com>
>> 
>> ---
>> 
>> diff --git a/Makefile b/Makefile
>> diff --git a/mm/sparse.c b/mm/sparse.c
>> index e06f514..d245e59 100644
>> --- a/mm/sparse.c
>> +++ b/mm/sparse.c
>> @@ -83,6 +83,8 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
>>  		return -EEXIST;
>> 
>>  	section = sparse_index_alloc(nid);
>> +	if (!section)
>> +		return -ENOMEM;
>>  	/*
>>  	 * This lock keeps two different sections from
>>  	 * reallocating for the same index
>
>Oddly enough, sparse_add_one_section() doesn't seem to like to check
>its allocations.  The usemap is checked, but not freed on error.  If you
>want to fix this up, I think it needs a little more love than just two
>lines.  

Er, right. I missed this point.

>
>Do you want to try to add some actual error handling to
>sparse_add_one_section()?

Yes, I will have a try. And memory_present() also doesn't check it.
More patches around this will come up soon. Since Andrew has included
the above patch, so I won't remake it with others together.

Andrew, is this OK for you?

Thanks.



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[Patch] mm/sparse.c: Improve the error handling for sparse_add_one_section()

[WANG Cong]

Improve the error handling for mm/sparse.c::sparse_add_one_section().
And I see no reason to check 'usemap' until holding the
'pgdat_resize_lock'. If someone knows, please let me know.

Note! This patch is _not_ tested yet, since it seems that I can't
configure sparse memory for i386 box. Sorry for this. ;(
I hope someone can help me to test it.

Cc: Christoph Lameter <clameter@sgi.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>

---
 mm/sparse.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

Index: linux-2.6/mm/sparse.c
===================================================================
--- linux-2.6.orig/mm/sparse.c
+++ linux-2.6/mm/sparse.c
@@ -391,9 +391,17 @@ int sparse_add_one_section(struct zone *
 	 * no locking for this, because it does its own
 	 * plus, it does a kmalloc
 	 */
-	sparse_index_init(section_nr, pgdat->node_id);
+	ret = sparse_index_init(section_nr, pgdat->node_id);
+	if (ret < 0)
+		return ret;
 	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
+	if (!memmap)
+		return -ENOMEM;
 	usemap = __kmalloc_section_usemap();
+	if (!usemap) {
+		__kfree_section_memmap(memmap, nr_pages);
+		return -ENOMEM;
+	}
 
 	pgdat_resize_lock(pgdat, &flags);
 
@@ -403,18 +411,13 @@ int sparse_add_one_section(struct zone *
 		goto out;
 	}
 
-	if (!usemap) {
-		ret = -ENOMEM;
-		goto out;
-	}
 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
 
 	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
 
 out:
 	pgdat_resize_unlock(pgdat, &flags);
-	if (ret <= 0)
-		__kfree_section_memmap(memmap, nr_pages);
+
 	return ret;
 }
 #endif

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Re: [Patch] mm/sparse.c: Improve the error handling for sparse_add_one_section()

[Yasunori Goto]

Hi, Cong-san.

>  	ms->section_mem_map |= SECTION_MARKED_PRESENT;
>  
>  	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
>  
>  out:
>  	pgdat_resize_unlock(pgdat, &flags);
> -	if (ret <= 0)
> -		__kfree_section_memmap(memmap, nr_pages);
> +
>  	return ret;
>  }
>  #endif

Hmm. When sparse_init_one_section() returns error, memmap and 
usemap should be free.

Thanks for your fixing.

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[Patch](Resend) mm/sparse.c: Improve the error handling for sparse_add_one_section()

[WANG Cong]

On Mon, Nov 26, 2007 at 07:19:49PM +0900, Yasunori Goto wrote:
>Hi, Cong-san.
>
>>  	ms->section_mem_map |= SECTION_MARKED_PRESENT;
>>  
>>  	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
>>  
>>  out:
>>  	pgdat_resize_unlock(pgdat, &flags);
>> -	if (ret <= 0)
>> -		__kfree_section_memmap(memmap, nr_pages);
>> +
>>  	return ret;
>>  }
>>  #endif
>
>Hmm. When sparse_init_one_section() returns error, memmap and 
>usemap should be free.

Hi, Yasunori.

Thanks for your comments. Is the following one fine for you?

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>

---

Index: linux-2.6/mm/sparse.c
===================================================================
--- linux-2.6.orig/mm/sparse.c
+++ linux-2.6/mm/sparse.c
@@ -391,9 +391,17 @@ int sparse_add_one_section(struct zone *
 	 * no locking for this, because it does its own
 	 * plus, it does a kmalloc
 	 */
-	sparse_index_init(section_nr, pgdat->node_id);
+	ret = sparse_index_init(section_nr, pgdat->node_id);
+	if (ret < 0)
+		return ret;
 	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
+	if (!memmap)
+		return -ENOMEM;
 	usemap = __kmalloc_section_usemap();
+	if (!usemap) {
+		__kfree_section_memmap(memmap, nr_pages);
+		return -ENOMEM;
+	}
 
 	pgdat_resize_lock(pgdat, &flags);
 
@@ -403,10 +411,6 @@ int sparse_add_one_section(struct zone *
 		goto out;
 	}
 
-	if (!usemap) {
-		ret = -ENOMEM;
-		goto out;
-	}
 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
 
 	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
@@ -414,7 +418,7 @@ int sparse_add_one_section(struct zone *
 out:
 	pgdat_resize_unlock(pgdat, &flags);
 	if (ret <= 0)
-		__kfree_section_memmap(memmap, nr_pages);
+		kfree(usemap);
 	return ret;
 }
 #endif

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Re: [Patch](Resend) mm/sparse.c: Improve the error handling for sparse_add_one_section()

[Yasunori Goto]

>  	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
> @@ -414,7 +418,7 @@ int sparse_add_one_section(struct zone *
>  out:
>  	pgdat_resize_unlock(pgdat, &flags);
>  	if (ret <= 0)
> -		__kfree_section_memmap(memmap, nr_pages);
> +		kfree(usemap);
>  	return ret;
>  }
>  #endif
> 

I guess you think __kfree_section_memmap() is not necessary due to
no implementation. But, it is still available when
CONFIG_SPARSEMEM_VMEMMAP is off. So, it should not be removed.


Bye.

-- 
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Re: [Patch](Resend) mm/sparse.c: Improve the error handling for sparse_add_one_section()

[Dave Hansen]

On Tue, 2007-11-27 at 10:26 +0800, WANG Cong wrote:
> 
> @@ -414,7 +418,7 @@ int sparse_add_one_section(struct zone *
>  out:
>         pgdat_resize_unlock(pgdat, &flags);
>         if (ret <= 0)
> -               __kfree_section_memmap(memmap, nr_pages);
> +               kfree(usemap);
>         return ret;
>  }
>  #endif 

Why did you get rid of the memmap free here?  A bad return from
sparse_init_one_section() indicates that we didn't use the memmap, so it
will leak otherwise.

-- Dave

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Re: [Patch](Resend) mm/sparse.c: Improve the error handling for sparse_add_one_section()

[WANG Cong]

On Tue, Nov 27, 2007 at 10:53:45AM -0800, Dave Hansen wrote:
>On Tue, 2007-11-27 at 10:26 +0800, WANG Cong wrote:
>> 
>> @@ -414,7 +418,7 @@ int sparse_add_one_section(struct zone *
>>  out:
>>         pgdat_resize_unlock(pgdat, &flags);
>>         if (ret <= 0)
>> -               __kfree_section_memmap(memmap, nr_pages);
>> +               kfree(usemap);
>>         return ret;
>>  }
>>  #endif 
>
>Why did you get rid of the memmap free here?  A bad return from
>sparse_init_one_section() indicates that we didn't use the memmap, so it
>will leak otherwise.

Sorry, I was confused by the recursion. This one should be OK.

Thanks.



Improve the error handling for mm/sparse.c::sparse_add_one_section().  And I
see no reason to check 'usemap' until holding the 'pgdat_resize_lock'.

Cc: Christoph Lameter <clameter@sgi.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>

---
Index: linux-2.6/mm/sparse.c
===================================================================
--- linux-2.6.orig/mm/sparse.c
+++ linux-2.6/mm/sparse.c
@@ -391,9 +391,17 @@ int sparse_add_one_section(struct zone *
 	 * no locking for this, because it does its own
 	 * plus, it does a kmalloc
 	 */
-	sparse_index_init(section_nr, pgdat->node_id);
+	ret = sparse_index_init(section_nr, pgdat->node_id);
+	if (ret < 0)
+		return ret;
 	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
+	if (!memmap)
+		return -ENOMEM;
 	usemap = __kmalloc_section_usemap();
+	if (!usemap) {
+		__kfree_section_memmap(memmap, nr_pages);
+		return -ENOMEM;
+	}
 
 	pgdat_resize_lock(pgdat, &flags);
 
@@ -403,18 +411,16 @@ int sparse_add_one_section(struct zone *
 		goto out;
 	}
 
-	if (!usemap) {
-		ret = -ENOMEM;
-		goto out;
-	}
 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
 
 	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
 
 out:
 	pgdat_resize_unlock(pgdat, &flags);
-	if (ret <= 0)
+	if (ret <= 0) {
+		kfree(usemap);
 		__kfree_section_memmap(memmap, nr_pages);
+	}
 	return ret;
 }
 #endif

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Re: [Patch](Resend) mm/sparse.c: Improve the error handling for sparse_add_one_section()

[Yasunori Goto]

Looks good to me.

Thanks.

Acked-by: Yasunori Goto <y-goto@jp.fujitsu.com>



> On Tue, Nov 27, 2007 at 10:53:45AM -0800, Dave Hansen wrote:
> >On Tue, 2007-11-27 at 10:26 +0800, WANG Cong wrote:
> >> 
> >> @@ -414,7 +418,7 @@ int sparse_add_one_section(struct zone *
> >>  out:
> >>         pgdat_resize_unlock(pgdat, &flags);
> >>         if (ret <= 0)
> >> -               __kfree_section_memmap(memmap, nr_pages);
> >> +               kfree(usemap);
> >>         return ret;
> >>  }
> >>  #endif 
> >
> >Why did you get rid of the memmap free here?  A bad return from
> >sparse_init_one_section() indicates that we didn't use the memmap, so it
> >will leak otherwise.
> 
> Sorry, I was confused by the recursion. This one should be OK.
> 
> Thanks.
> 
> 
> 
> Improve the error handling for mm/sparse.c::sparse_add_one_section().  And I
> see no reason to check 'usemap' until holding the 'pgdat_resize_lock'.
> 
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: Dave Hansen <haveblue@us.ibm.com>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
> Cc: Andy Whitcroft <apw@shadowen.org>
> Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
> 
> ---
> Index: linux-2.6/mm/sparse.c
> ===================================================================
> --- linux-2.6.orig/mm/sparse.c
> +++ linux-2.6/mm/sparse.c
> @@ -391,9 +391,17 @@ int sparse_add_one_section(struct zone *
>  	 * no locking for this, because it does its own
>  	 * plus, it does a kmalloc
>  	 */
> -	sparse_index_init(section_nr, pgdat->node_id);
> +	ret = sparse_index_init(section_nr, pgdat->node_id);
> +	if (ret < 0)
> +		return ret;
>  	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
> +	if (!memmap)
> +		return -ENOMEM;
>  	usemap = __kmalloc_section_usemap();
> +	if (!usemap) {
> +		__kfree_section_memmap(memmap, nr_pages);
> +		return -ENOMEM;
> +	}
>  
>  	pgdat_resize_lock(pgdat, &flags);
>  
> @@ -403,18 +411,16 @@ int sparse_add_one_section(struct zone *
>  		goto out;
>  	}
>  
> -	if (!usemap) {
> -		ret = -ENOMEM;
> -		goto out;
> -	}
>  	ms->section_mem_map |= SECTION_MARKED_PRESENT;
>  
>  	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
>  
>  out:
>  	pgdat_resize_unlock(pgdat, &flags);
> -	if (ret <= 0)
> +	if (ret <= 0) {
> +		kfree(usemap);
>  		__kfree_section_memmap(memmap, nr_pages);
> +	}
>  	return ret;
>  }
>  #endif

-- 
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Re: [Patch](Resend) mm/sparse.c: Improve the error handling for sparse_add_one_section()

[Dave Hansen]

This looks fine now.

Acked-by: Dave Hansen <haveblue@us.ibm.com> 

-- Dave

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