gfp: include __GFP_NOWARN in GFP_NOWAIT

GFP_NOWAIT callers are always prepared for their allocations to fail
because they fail so frequently.  Forcing the callers to remember to add
__GFP_NOWARN is just annoying and leads to an endless stream of patches
for the places where we forgot to add it.

We can now remove __GFP_NOWARN from all the callers which specify
GFP_NOWAIT, but I'd rather wait a cycle and send patches to each
maintainer instead of creating a big pile of merge conflicts.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Matthew Wilcox (Oracle)

include/linux/gfp_types.h

@@ -274,7 +274,8 @@ typedef unsigned int __bitwise gfp_t;
  * accounted to kmemcg.
  *
  * %GFP_NOWAIT is for kernel allocations that should not stall for direct
- * reclaim, start physical IO or use any filesystem callback.
+ * reclaim, start physical IO or use any filesystem callback.  It is very
+ * likely to fail to allocate memory, even for very small allocations.
  *
  * %GFP_NOIO will use direct reclaim to discard clean pages or slab pages
  * that do not require the starting of any physical IO.
@@ -325,7 +326,7 @@ typedef unsigned int __bitwise gfp_t;
 #define GFP_ATOMIC	(__GFP_HIGH|__GFP_KSWAPD_RECLAIM)
 #define GFP_KERNEL	(__GFP_RECLAIM | __GFP_IO | __GFP_FS)
 #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT)
-#define GFP_NOWAIT	(__GFP_KSWAPD_RECLAIM)
+#define GFP_NOWAIT	(__GFP_KSWAPD_RECLAIM | __GFP_NOWARN)
 #define GFP_NOIO	(__GFP_RECLAIM)
 #define GFP_NOFS	(__GFP_RECLAIM | __GFP_IO)
 #define GFP_USER	(__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL)