path: root/mm/percpu-km.c
diff options
authorDennis Zhou <>2018-02-16 12:07:19 -0600
committerTejun Heo <>2018-02-18 05:33:00 -0800
commit47504ee04b9241548ae2c28be7d0b01cff3b7aa6 (patch)
treed2a55fe53d065220a4610011cb624811e74085db /mm/percpu-km.c
parent15d9f3d116c02a485441d758d9ca0a2e4f3b30be (diff)
percpu: add __GFP_NORETRY semantics to the percpu balancing path
Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] Signed-off-by: Dennis Zhou <> Suggested-by: Daniel Borkmann <> Reported-by: Acked-by: Christoph Lameter <> Signed-off-by: Tejun Heo <>
Diffstat (limited to 'mm/percpu-km.c')
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index d2a76642c4ae..0d88d7bd5706 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -34,7 +34,7 @@
#include <linux/log2.h>
static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
- int page_start, int page_end)
+ int page_start, int page_end, gfp_t gfp)
return 0;
@@ -45,18 +45,18 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
/* nada */
-static struct pcpu_chunk *pcpu_create_chunk(void)
+static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
struct pcpu_chunk *chunk;
struct page *pages;
int i;
- chunk = pcpu_alloc_chunk();
+ chunk = pcpu_alloc_chunk(gfp);
if (!chunk)
return NULL;
- pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages));
+ pages = alloc_pages(gfp | GFP_KERNEL, order_base_2(nr_pages));
if (!pages) {
return NULL;