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-rw-r--r--mm/mempool.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/mm/mempool.c b/mm/mempool.c
index 7924f4f..07c383d 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -310,25 +310,36 @@ EXPORT_SYMBOL(mempool_resize);
* returns NULL. Note that due to preallocation, this function
* *never* fails when called from process contexts. (it might
* fail if called from an IRQ context.)
- * Note: using __GFP_ZERO is not supported.
+ * Note: neither __GFP_NOMEMALLOC nor __GFP_ZERO are supported.
*/
-void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
+void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
{
void *element;
unsigned long flags;
wait_queue_t wait;
gfp_t gfp_temp;
+ /* If oom killed, memory reserves are essential to prevent livelock */
+ VM_WARN_ON_ONCE(gfp_mask & __GFP_NOMEMALLOC);
+ /* No element size to zero on allocation */
VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
+
might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
- gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
gfp_mask |= __GFP_NOWARN; /* failures are OK */
gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
repeat_alloc:
+ if (likely(pool->curr_nr)) {
+ /*
+ * Don't allocate from emergency reserves if there are
+ * elements available. This check is racy, but it will
+ * be rechecked each loop.
+ */
+ gfp_temp |= __GFP_NOMEMALLOC;
+ }
element = pool->alloc(gfp_temp, pool->pool_data);
if (likely(element != NULL))
@@ -352,11 +363,12 @@ repeat_alloc:
* We use gfp mask w/o direct reclaim or IO for the first round. If
* alloc failed with that and @pool was empty, retry immediately.
*/
- if (gfp_temp != gfp_mask) {
+ if ((gfp_temp & ~__GFP_NOMEMALLOC) != gfp_mask) {
spin_unlock_irqrestore(&pool->lock, flags);
gfp_temp = gfp_mask;
goto repeat_alloc;
}
+ gfp_temp = gfp_mask;
/* We must not sleep if !__GFP_DIRECT_RECLAIM */
if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
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