mm/mempool: use might_alloc()

mempool are generally used for GFP_NOIO, so this wont benefit all that
much because might_alloc currently only checks GFP_NOFS.  But it does
validate against mmu notifier pte zapping, some might catch some drivers
doing really silly things, plus it's a bit more meaningful in what we're
checking for here.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Daniel Vetter <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Roman Gushchin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: danvet

mm/mempool.c

@@ -379,7 +379,7 @@ void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
 	gfp_t gfp_temp;
 
 	VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
-	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
+	might_alloc(gfp_mask);
 
 	gfp_mask |= __GFP_NOMEMALLOC;	/* don't allocate emergency reserves */
 	gfp_mask |= __GFP_NORETRY;	/* don't loop in __alloc_pages */