[PATCH 1/2] powerpc/vmemmap: Fix memory leak with vmemmap list allocation failures.

[PATCH 1/2] powerpc/vmemmap: Fix memory leak with vmemmap list allocation failures.

[Aneesh Kumar K.V]

If we fail to allocate vmemmap list, we don't keep track of allocated
vmemmap block buf. Hence on section deactivate we skip vmemmap block
buf free. This results in memory leak.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/mm/init_64.c | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 152aa0200cef..8a198504c0e1 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -162,16 +162,16 @@ static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
 	return next++;
 }
 
-static __meminit void vmemmap_list_populate(unsigned long phys,
-					    unsigned long start,
-					    int node)
+static __meminit int vmemmap_list_populate(unsigned long phys,
+					   unsigned long start,
+					   int node)
 {
 	struct vmemmap_backing *vmem_back;
 
 	vmem_back = vmemmap_list_alloc(node);
 	if (unlikely(!vmem_back)) {
-		WARN_ON(1);
-		return;
+		pr_debug("vmemap list allocation failed\n");
+		return -ENOMEM;
 	}
 
 	vmem_back->phys = phys;
@@ -179,6 +179,7 @@ static __meminit void vmemmap_list_populate(unsigned long phys,
 	vmem_back->list = vmemmap_list;
 
 	vmemmap_list = vmem_back;
+	return 0;
 }
 
 static bool altmap_cross_boundary(struct vmem_altmap *altmap, unsigned long start,
@@ -199,6 +200,7 @@ static bool altmap_cross_boundary(struct vmem_altmap *altmap, unsigned long star
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 		struct vmem_altmap *altmap)
 {
+	bool altmap_alloc;
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
 
 	/* Align to the page size of the linear mapping. */
@@ -228,13 +230,32 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			p = altmap_alloc_block_buf(page_size, altmap);
 			if (!p)
 				pr_debug("altmap block allocation failed, falling back to system memory");
+			else
+				altmap_alloc = true;
 		}
-		if (!p)
+		if (!p) {
 			p = vmemmap_alloc_block_buf(page_size, node);
+			altmap_alloc = false;
+		}
 		if (!p)
 			return -ENOMEM;
 
-		vmemmap_list_populate(__pa(p), start, node);
+		if (vmemmap_list_populate(__pa(p), start, node)) {
+			/*
+			 * If we don't populate vmemap list, we don't have
+			 * the ability to free the allocated vmemmap
+			 * pages in section_deactivate. Hence free them
+			 * here.
+			 */
+			int nr_pfns = page_size >> PAGE_SHIFT;
+			unsigned long page_order = get_order(page_size);
+
+			if (altmap_alloc)
+				vmem_altmap_free(altmap, nr_pfns);
+			else
+				free_pages((unsigned long)p, page_order);
+			return -ENOMEM;
+		}
 
 		pr_debug("      * %016lx..%016lx allocated at %p\n",
 			 start, start + page_size, p);
-- 
2.26.2

[PATCH 2/2] powerpc/vmemmap: Don't warn if we don't find a mapping vmemmap list entry

[Aneesh Kumar K.V]

Now that we are handling vmemmap list allocation failure correctly, don't
WARN in section deactivate when we don't find a mapping vmemmap list entry.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/mm/init_64.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 8a198504c0e1..3ffe8b84aab2 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -285,10 +285,8 @@ static unsigned long vmemmap_list_free(unsigned long start)
 		vmem_back_prev = vmem_back;
 	}
 
-	if (unlikely(!vmem_back)) {
-		WARN_ON(1);
+	if (unlikely(!vmem_back))
 		return 0;
-	}
 
 	/* remove it from vmemmap_list */
 	if (vmem_back == vmemmap_list) /* remove head */
-- 
2.26.2

Re: [PATCH 1/2] powerpc/vmemmap: Fix memory leak with vmemmap list allocation failures.

[Michael Ellerman]

On Fri, 31 Jul 2020 17:04:59 +0530, Aneesh Kumar K.V wrote:
> If we fail to allocate vmemmap list, we don't keep track of allocated
> vmemmap block buf. Hence on section deactivate we skip vmemmap block
> buf free. This results in memory leak.

Applied to powerpc/next.

[1/2] powerpc/vmemmap: Fix memory leak with vmemmap list allocation failures.
      https://git.kernel.org/powerpc/c/ccaea15296f9773abd43aaa17ee4b88848e4a505
[2/2] powerpc/vmemmap: Don't warn if we don't find a mapping vmemmap list entry
      https://git.kernel.org/powerpc/c/1c0a7ac0ec63ee626f669c9a4e278f6ae1dbfcf2

cheers