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

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 <[email protected]>

Cc Christoph Lameter <[email protected]>

Cc Rik van Riel <[email protected]>

---

Makefile +0 -0

mm/sparse.c +0 -0

index e06f514..d245e59 100644

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 <[email protected]>

Cc Christoph Lameter <[email protected]>

Cc Rik van Riel <[email protected]>

---

Makefile +0 -0

mm/sparse.c +0 -0

index e06f514..d245e59 100644

Quoted 17 lines · 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 <[email protected]>

Cc Christoph Lameter <[email protected]>

Cc Rik van Riel <[email protected]>

---

Makefile +0 -0

mm/sparse.c +0 -0

index e06f514..d245e59 100644
@@ -83,6 +83,8 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
 		return -EEXIST;
 

mm/sparse.c static int __meminit sparse_index_init(unsigned long section_nr, int nid) · line 90

Quoted 6 lines

mm/sparse.c +2 -0

 	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()?

Hi, Cong-san.

Quoted 4 lines

(quoted diff) +0 -0

 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
 
 	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);

Review

Quoted 8 lines

out:

(quoted diff) +1 -2

 	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.

Review int sparse_add_one_section(struct zone * · line 424

Quoted 10 lines · WANG Cong

(quoted diff) +1 -1

@@ -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.

Quoted 15 lines · WANG Cong

mm/sparse.c int sparse_add_one_section(struct zone * · line 424

Quoted 10 lines

mm/sparse.c +1 -1

@@ -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 <[email protected]>

Cc Dave Hansen <[email protected]>

Cc Rik van Riel <[email protected]>

Cc Yasunori Goto <[email protected]>

Cc Andy Whitcroft <[email protected]>

Signed-off-by WANG Cong <[email protected]>

---
Index: linux-2.6/mm/sparse.c
===================================================================

mm/sparse.c +12 -6

@@ -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