[PATCH] fix BUG_ON(!PageSlab) from fallback_alloc

Hugh Dickins · Linus Torvalds · commit b6a60451813b · 2007-01-05T23:55:23.000-08:00
pdflush hit the BUG_ON(!PageSlab(page)) in kmem_freepages called from
fallback_alloc: cache_grow already freed those pages when alloc_slabmgmt
failed.  But it wouldn't have freed them if __GFP_NO_GROW, so make sure
fallback_alloc doesn't waste its time on that case.

Signed-off-by: Hugh Dickins &lt;hugh@veritas.com&gt;
Acked-by: Christoph Lameter &lt;clameter@sgi.com&gt;
Acked-by: Pekka J Enberg &lt;penberg@cs.helsinki.fi&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
diff --git a/mm/slab.c b/mm/slab.c
@@ -3281,7 +3281,7 @@ void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
 					flags | GFP_THISNODE, nid);
 	}
 
-	if (!obj) {
+	if (!obj && !(flags & __GFP_NO_GROW)) {
 		/*
 		 * This allocation will be performed within the constraints
 		 * of the current cpuset / memory policy requirements.
@@ -3310,7 +3310,7 @@ void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
 					 */
 					goto retry;
 			} else {
-				kmem_freepages(cache, obj);
+				/* cache_grow already freed obj */
 				obj = NULL;
 			}
 		}

Original file line number	Diff line number	Diff line change
`@@ -3281,7 +3281,7 @@ void fallback_alloc(struct kmem_cache cache, gfp_t flags)`
`3281`	`3281`	`flags \| GFP_THISNODE, nid);`
`3282`	`3282`	`}`
`3283`	`3283`
`3284`		`- if (!obj) {`
	`3284`	`+ if (!obj && !(flags & __GFP_NO_GROW)) {`
`3285`	`3285`	`/*`
`3286`	`3286`	`* This allocation will be performed within the constraints`
`3287`	`3287`	`* of the current cpuset / memory policy requirements.`
`@@ -3310,7 +3310,7 @@ void fallback_alloc(struct kmem_cache cache, gfp_t flags)`
`3310`	`3310`	`*/`
`3311`	`3311`	`goto retry;`
`3312`	`3312`	`} else {`
`3313`		`- kmem_freepages(cache, obj);`
	`3313`	`+ /* cache_grow already freed obj */`
`3314`	`3314`	`obj = NULL;`
`3315`	`3315`	`}`
`3316`	`3316`	`}`