Frag allocator is not designed for fragsz > PAGE_SIZE. So, check and return
the error at the beginning of __page_frag_alloc_align(), instead of
succeed for a few times, then fail due to not refilling the cache.
Signed-off-by: Haiyang Zhang <haiya...@microsoft.com>
---
mm/page_frag_cache.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c
index d2423f30577e..d6bf022087e7 100644
--- a/mm/page_frag_cache.c
+++ b/mm/page_frag_cache.c
@@ -98,6 +98,15 @@ void *__page_frag_alloc_align(struct page_frag_cache *nc,
unsigned int size, offset;
struct page *page;
+ if (unlikely(fragsz > PAGE_SIZE)) {
+ /*
+ * The caller is trying to allocate a fragment
+ * with fragsz > PAGE_SIZE which is not supported
+ * by design. So we simply return NULL here.
+ */
+ return NULL;
+ }
+
if (unlikely(!encoded_page)) {
refill:
page = __page_frag_cache_refill(nc, gfp_mask);
@@ -119,19 +128,6 @@ void *__page_frag_alloc_align(struct page_frag_cache *nc,
size = PAGE_SIZE << encoded_page_decode_order(encoded_page);
offset = __ALIGN_KERNEL_MASK(nc->offset, ~align_mask);
if (unlikely(offset + fragsz > size)) {
- if (unlikely(fragsz > PAGE_SIZE)) {
- /*
- * The caller is trying to allocate a fragment
- * with fragsz > PAGE_SIZE but the cache isn't big
- * enough to satisfy the request, this may
- * happen in low memory conditions.
- * We don't release the cache page because
- * it could make memory pressure worse
- * so we simply return NULL here.
- */
- return NULL;
- }
-
page = encoded_page_decode_page(encoded_page);
if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
--
2.34.1
