mm/page_alloc: rename alloc_mask to alloc_gfp

Patch series "Rationalise __alloc_pages wrappers", v3.

I was poking around the __alloc_pages variants trying to understand why
they each exist, and couldn't really find a good justification for keeping
__alloc_pages and __alloc_pages_nodemask as separate functions.  That led
to getting rid of alloc_pages_current() and then I noticed the
documentation was bad, and then I noticed the mempolicy documentation
wasn't included.

Anyway, this is all cleanups & doc fixes.

This patch (of 7):

We have two masks involved -- the nodemask and the gfp mask, so alloc_mask
is an unclear name.

Link: https://lkml.kernel.org/r/20210225150642.2582252-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Matthew Wilcox (Oracle)

mm/page_alloc.c

@@ -4966,7 +4966,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 
 static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 		int preferred_nid, nodemask_t *nodemask,
-		struct alloc_context *ac, gfp_t *alloc_mask,
+		struct alloc_context *ac, gfp_t *alloc_gfp,
 		unsigned int *alloc_flags)
 {
 	ac->highest_zoneidx = gfp_zone(gfp_mask);
@@ -4975,7 +4975,7 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 	ac->migratetype = gfp_migratetype(gfp_mask);
 
 	if (cpusets_enabled()) {
-		*alloc_mask |= __GFP_HARDWALL;
+		*alloc_gfp |= __GFP_HARDWALL;
 		/*
 		 * When we are in the interrupt context, it is irrelevant
 		 * to the current task context. It means that any node ok.
@@ -5019,7 +5019,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 {
 	struct page *page;
 	unsigned int alloc_flags = ALLOC_WMARK_LOW;
-	gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
+	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
 	struct alloc_context ac = { };
 
 	/*
@@ -5032,8 +5032,9 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 	}
 
 	gfp_mask &= gfp_allowed_mask;
-	alloc_mask = gfp_mask;
-	if (!prepare_alloc_pages(gfp_mask, order, preferred_nid, nodemask, &ac, &alloc_mask, &alloc_flags))
+	alloc_gfp = gfp_mask;
+	if (!prepare_alloc_pages(gfp_mask, order, preferred_nid, nodemask, &ac,
+			&alloc_gfp, &alloc_flags))
 		return NULL;
 
 	/*
@@ -5043,7 +5044,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 	alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp_mask);
 
 	/* First allocation attempt */
-	page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
+	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
 	if (likely(page))
 		goto out;
 
@@ -5053,7 +5054,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 	 * from a particular context which has been marked by
 	 * memalloc_no{fs,io}_{save,restore}.
 	 */
-	alloc_mask = current_gfp_context(gfp_mask);
+	alloc_gfp = current_gfp_context(gfp_mask);
 	ac.spread_dirty_pages = false;
 
 	/*
@@ -5062,7 +5063,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 	 */
 	ac.nodemask = nodemask;
 
-	page = __alloc_pages_slowpath(alloc_mask, order, &ac);
+	page = __alloc_pages_slowpath(alloc_gfp, order, &ac);
 
 out:
 	if (memcg_kmem_enabled() && (gfp_mask & __GFP_ACCOUNT) && page &&
@@ -5071,7 +5072,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 		page = NULL;
 	}
 
-	trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
+	trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
 
 	return page;
 }