[PATCH] fix suppression of page allocation failure warnings

Somebody somewhere is stomping on PF_NOWARN, and page allocation
failure warnings are coming out of the wrong places.

So change the handling of current->flags to be:

int pf_flags = current->flags;

current->flags |= PF_NOWARN;
...
current->flags = pf_flags;

which is a generally more robust approach.

drivers/scsi/scsi.c

@@ -2453,6 +2453,7 @@ struct scatterlist *scsi_alloc_sgtable(Scsi_Cmnd *SCpnt, int gfp_mask)
 {
 	struct scsi_host_sg_pool *sgp;
 	struct scatterlist *sgl;
+	int pf_flags;
 
 	BUG_ON(!SCpnt->use_sg);
 
@@ -2467,9 +2468,10 @@ struct scatterlist *scsi_alloc_sgtable(Scsi_Cmnd *SCpnt, int gfp_mask)
 
 	sgp = scsi_sg_pools + SCpnt->sglist_len;
 
+	pf_flags = current->flags;
 	current->flags |= PF_NOWARN;
 	sgl = mempool_alloc(sgp->pool, gfp_mask);
-	current->flags &= ~PF_NOWARN;
+	current->flags = pf_flags;
 	if (sgl) {
 		memset(sgl, 0, sgp->size);
 		return sgl;

fs/bio.c

@@ -137,6 +137,7 @@ struct bio *bio_alloc(int gfp_mask, int nr_iovecs)
 {
 	struct bio *bio;
 	struct bio_vec *bvl = NULL;
+	int pf_flags = current->flags;
 
 	current->flags |= PF_NOWARN;
 	bio = mempool_alloc(bio_pool, gfp_mask);
@@ -153,7 +154,7 @@ struct bio *bio_alloc(int gfp_mask, int nr_iovecs)
 	mempool_free(bio, bio_pool);
 	bio = NULL;
 out:
-	current->flags &= ~PF_NOWARN;
+	current->flags = pf_flags;
 	return bio;
 }
 

fs/buffer.c

@@ -936,9 +936,11 @@ create_buffers(struct page * page, unsigned long size, int retry)
 	head = NULL;
 	offset = PAGE_SIZE;
 	while ((offset -= size) >= 0) {
+		int pf_flags = current->flags;
+
 		current->flags |= PF_NOWARN;
 		bh = alloc_buffer_head();
-		current->flags &= ~PF_NOWARN;
+		current->flags = pf_flags;
 		if (!bh)
 			goto no_grow;
 

mm/mempool.c

@@ -187,11 +187,12 @@ void * mempool_alloc(mempool_t *pool, int gfp_mask)
 	int curr_nr;
 	DECLARE_WAITQUEUE(wait, current);
 	int gfp_nowait = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
+	int pf_flags = current->flags;
 
 repeat_alloc:
 	current->flags |= PF_NOWARN;
 	element = pool->alloc(gfp_nowait, pool->pool_data);
-	current->flags &= ~PF_NOWARN;
+	current->flags = pf_flags;
 	if (likely(element != NULL))
 		return element;
 

mm/swap_state.c

@@ -119,7 +119,7 @@ void __delete_from_swap_cache(struct page *page)
 int add_to_swap(struct page * page)
 {
 	swp_entry_t entry;
-	int flags;
+	int pf_flags;
 
 	if (!PageLocked(page))
 		BUG();
@@ -142,7 +142,7 @@ int add_to_swap(struct page * page)
 		 * just not all of them.
 		 */
 
-		flags = current->flags;
+		pf_flags = current->flags;
 		current->flags &= ~PF_MEMALLOC;
 		current->flags |= PF_NOWARN;
 		ClearPageUptodate(page);		/* why? */
@@ -154,20 +154,20 @@ int add_to_swap(struct page * page)
 		 */
 		switch (add_to_swap_cache(page, entry)) {
 		case 0:				/* Success */
-			current->flags = flags;
+			current->flags = pf_flags;
 			SetPageUptodate(page);
 			set_page_dirty(page);
 			swap_free(entry);
 			return 1;
 		case -ENOMEM:			/* radix-tree allocation */
-			current->flags = flags;
+			current->flags = pf_flags;
 			swap_free(entry);
 			return 0;
 		default:			/* ENOENT: raced */
 			break;
 		}
 		/* Raced with "speculative" read_swap_cache_async */
-		current->flags = flags;
+		current->flags = pf_flags;
 		swap_free(entry);
 	}
 }