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

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Message-ID: <20071128124420.GJ2464@hacking>
Date:	Wed, 28 Nov 2007 20:44:20 +0800
From:	WANG Cong <xiyou.wangcong@...il.com>
To:	Dave Hansen <haveblue@...ibm.com>
Cc:	WANG Cong <xiyou.wangcong@...il.com>,
	Yasunori Goto <y-goto@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	Christoph Lameter <clameter@....com>,
	Andrew Morton <akpm@...l.org>, linux-mm@...ck.org,
	Andy Whitcroft <apw@...dowen.org>
Subject: Re: [Patch](Resend) mm/sparse.c: Improve the error handling for
	sparse_add_one_section()

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@....com>
Cc: Dave Hansen <haveblue@...ibm.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Yasunori Goto <y-goto@...fujitsu.com>
Cc: Andy Whitcroft <apw@...dowen.org>
Signed-off-by: WANG Cong <xiyou.wangcong@...il.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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