mm: reduce try_to_compact_pages parameters

Expand the usage of the struct alloc_context introduced in the previous
patch also for calling try_to_compact_pages(), to reduce the number of its
parameters.  Since the function is in different compilation unit, we need
to move alloc_context definition in the shared mm/internal.h header.

With this change we get simpler code and small savings of code size and stack
usage:

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-27 (-27)
function                                     old     new   delta
__alloc_pages_direct_compact                 283     256     -27
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-13 (-13)
function                                     old     new   delta
try_to_compact_pages                         582     569     -13

Stack usage of __alloc_pages_direct_compact goes from 24 to none (per
scripts/checkstack.pl).

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 3238ffa..f2efda2 100644 (file)
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -21,6 +21,8 @@
 /* Zone lock or lru_lock was contended in async compaction */
 #define COMPACT_CONTENDED_LOCK 2
 
+struct alloc_context; /* in mm/internal.h */
+
 #ifdef CONFIG_COMPACTION
 extern int sysctl_compact_memory;
 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
@@ -30,10 +32,9 @@ extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
                        void __user *buffer, size_t *length, loff_t *ppos);
 
 extern int fragmentation_index(struct zone *zone, unsigned int order);
-extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
-                       int order, gfp_t gfp_mask, nodemask_t *mask,
-                       enum migrate_mode mode, int *contended,
-                       int alloc_flags, int classzone_idx);
+extern unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
+                       int alloc_flags, const struct alloc_context *ac,
+                       enum migrate_mode mode, int *contended);
 extern void compact_pgdat(pg_data_t *pgdat, int order);
 extern void reset_isolation_suitable(pg_data_t *pgdat);
 extern unsigned long compaction_suitable(struct zone *zone, int order,
@@ -101,10 +102,10 @@ static inline bool compaction_restarting(struct zone *zone, int order)
 }
 
 #else
-static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
-                       int order, gfp_t gfp_mask, nodemask_t *nodemask,
-                       enum migrate_mode mode, int *contended,
-                       int alloc_flags, int classzone_idx)
+static inline unsigned long try_to_compact_pages(gfp_t gfp_mask,
+                       unsigned int order, int alloc_flags,
+                       const struct alloc_context *ac,
+                       enum migrate_mode mode, int *contended)
 {
        return COMPACT_CONTINUE;
 }

diff --git a/mm/compaction.c b/mm/compaction.c
index 546e571..9c7e690 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1335,22 +1335,20 @@ int sysctl_extfrag_threshold = 500;
 
 /**
  * try_to_compact_pages - Direct compact to satisfy a high-order allocation
- * @zonelist: The zonelist used for the current allocation
- * @order: The order of the current allocation
  * @gfp_mask: The GFP mask of the current allocation
- * @nodemask: The allowed nodes to allocate from
+ * @order: The order of the current allocation
+ * @alloc_flags: The allocation flags of the current allocation
+ * @ac: The context of current allocation
  * @mode: The migration mode for async, sync light, or sync migration
  * @contended: Return value that determines if compaction was aborted due to
  *            need_resched() or lock contention
  *
  * This is the main entry point for direct page compaction.
  */
-unsigned long try_to_compact_pages(struct zonelist *zonelist,
-                       int order, gfp_t gfp_mask, nodemask_t *nodemask,
-                       enum migrate_mode mode, int *contended,
-                       int alloc_flags, int classzone_idx)
+unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
+                       int alloc_flags, const struct alloc_context *ac,
+                       enum migrate_mode mode, int *contended)
 {
-       enum zone_type high_zoneidx = gfp_zone(gfp_mask);
        int may_enter_fs = gfp_mask & __GFP_FS;
        int may_perform_io = gfp_mask & __GFP_IO;
        struct zoneref *z;
@@ -1365,8 +1363,8 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
                return COMPACT_SKIPPED;
 
        /* Compact each zone in the list */
-       for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
-                                                               nodemask) {
+       for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
+                                                               ac->nodemask) {
                int status;
                int zone_contended;
 
@@ -1374,7 +1372,8 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
                        continue;
 
                status = compact_zone_order(zone, order, gfp_mask, mode,
-                               &zone_contended, alloc_flags, classzone_idx);
+                               &zone_contended, alloc_flags,
+                               ac->classzone_idx);
                rc = max(status, rc);
                /*
                 * It takes at least one zone that wasn't lock contended
@@ -1384,7 +1383,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 
                /* If a normal allocation would succeed, stop compacting */
                if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
-                                       classzone_idx, alloc_flags)) {
+                                       ac->classzone_idx, alloc_flags)) {
                        /*
                         * We think the allocation will succeed in this zone,
                         * but it is not certain, hence the false. The caller

diff --git a/mm/internal.h b/mm/internal.h
index efad241..c4d6c9b 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -109,6 +109,28 @@ extern pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address);
  * in mm/page_alloc.c
  */
 
+/*
+ * Structure for holding the mostly immutable allocation parameters passed
+ * between functions involved in allocations, including the alloc_pages*
+ * family of functions.
+ *
+ * nodemask, migratetype and high_zoneidx are initialized only once in
+ * __alloc_pages_nodemask() and then never change.
+ *
+ * zonelist, preferred_zone and classzone_idx are set first in
+ * __alloc_pages_nodemask() for the fast path, and might be later changed
+ * in __alloc_pages_slowpath(). All other functions pass the whole strucure
+ * by a const pointer.
+ */
+struct alloc_context {
+       struct zonelist *zonelist;
+       nodemask_t *nodemask;
+       struct zone *preferred_zone;
+       int classzone_idx;
+       int migratetype;
+       enum zone_type high_zoneidx;
+};
+
 /*
  * Locate the struct page for both the matching buddy in our
  * pair (buddy1) and the combined O(n+1) page they form (page).

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4aead0b..d664eb9 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -232,27 +232,6 @@ EXPORT_SYMBOL(nr_node_ids);
 EXPORT_SYMBOL(nr_online_nodes);
 #endif
 
-/*
- * Structure for holding the mostly immutable allocation parameters passed
- * between alloc_pages* family of functions.
- *
- * nodemask, migratetype and high_zoneidx are initialized only once in
- * __alloc_pages_nodemask() and then never change.
- *
- * zonelist, preferred_zone and classzone_idx are set first in
- * __alloc_pages_nodemask() for the fast path, and might be later changed
- * in __alloc_pages_slowpath(). All other functions pass the whole strucure
- * by a const pointer.
- */
-struct alloc_context {
-       struct zonelist *zonelist;
-       nodemask_t *nodemask;
-       struct zone *preferred_zone;
-       int classzone_idx;
-       int migratetype;
-       enum zone_type high_zoneidx;
-};
-
 int page_group_by_mobility_disabled __read_mostly;
 
 void set_pageblock_migratetype(struct page *page, int migratetype)
@@ -2429,10 +2408,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
                return NULL;
 
        current->flags |= PF_MEMALLOC;
-       compact_result = try_to_compact_pages(ac->zonelist, order, gfp_mask,
-                                               ac->nodemask, mode,
-                                               contended_compaction,
-                                               alloc_flags, ac->classzone_idx);
+       compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
+                                               mode, contended_compaction);
        current->flags &= ~PF_MEMALLOC;
 
        switch (compact_result) {