[RFC 3/4] mm, page_alloc: make alloc_flags a separate parameter again

From: Vlastimil Babka
Date: Wed Aug 06 2014 - 09:58:31 EST


The alloc_flags parameter often changes between the various alloc_pages*
function so make it separate again to prevent the need for saving it etc.
It is also heavily used so it might benefit from being passed by register.
---
mm/page_alloc.c | 62 +++++++++++++++++++++------------------------------------
1 file changed, 23 insertions(+), 39 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 399d40d..c06ad53 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -238,7 +238,6 @@ struct alloc_info {

unsigned int order;
gfp_t gfp_mask;
- int alloc_flags;
int classzone_idx;
int migratetype;
enum zone_type high_zoneidx;
@@ -1956,10 +1955,9 @@ static void reset_alloc_batches(struct zone *preferred_zone)
* a page.
*/
static struct page *
-get_page_from_freelist(const struct alloc_info *ai)
+get_page_from_freelist(int alloc_flags, const struct alloc_info *ai)
{
const unsigned int order = ai->order;
- int alloc_flags = ai->alloc_flags;
struct zonelist *zonelist = ai->zonelist;
struct zoneref *z;
struct page *page = NULL;
@@ -2253,11 +2251,10 @@ should_alloc_retry(gfp_t gfp_mask, unsigned int order,
}

static inline struct page *
-__alloc_pages_may_oom(struct alloc_info *ai)
+__alloc_pages_may_oom(int alloc_flags, struct alloc_info *ai)
{
struct page *page;
const gfp_t gfp_mask = ai->gfp_mask;
- const int alloc_flags_saved = ai->alloc_flags;

/* Acquire the per-zone oom lock for each zone */
if (!oom_zonelist_trylock(ai->zonelist, ai->gfp_mask)) {
@@ -2271,10 +2268,8 @@ __alloc_pages_may_oom(struct alloc_info *ai)
* we're still under heavy pressure.
*/
ai->gfp_mask |= __GFP_HARDWALL;
- ai->alloc_flags = ALLOC_WMARK_HIGH|ALLOC_CPUSET;
- page = get_page_from_freelist(ai);
+ page = get_page_from_freelist(ALLOC_WMARK_HIGH|ALLOC_CPUSET, ai);
ai->gfp_mask = gfp_mask;
- ai->alloc_flags = alloc_flags_saved;

if (page)
goto out;
@@ -2307,13 +2302,12 @@ out:
#ifdef CONFIG_COMPACTION
/* Try memory compaction for high-order allocations before reclaim */
static struct page *
-__alloc_pages_direct_compact(struct alloc_info *ai, enum migrate_mode mode,
- bool *contended_compaction, bool *deferred_compaction,
- unsigned long *did_some_progress)
+__alloc_pages_direct_compact(int alloc_flags, const struct alloc_info *ai,
+ enum migrate_mode mode, bool *contended_compaction,
+ bool *deferred_compaction, unsigned long *did_some_progress)
{
const unsigned int order = ai->order;
struct zone *preferred_zone = ai->preferred_zone;
- const int alloc_flags_saved = ai->alloc_flags;

if (!order)
return NULL;
@@ -2336,9 +2330,8 @@ __alloc_pages_direct_compact(struct alloc_info *ai, enum migrate_mode mode,
drain_pages(get_cpu());
put_cpu();

- ai->alloc_flags &= ~ALLOC_NO_WATERMARKS;
- page = get_page_from_freelist(ai);
- ai->alloc_flags = alloc_flags_saved;
+ page = get_page_from_freelist(alloc_flags &
+ ~ALLOC_NO_WATERMARKS, ai);

if (page) {
preferred_zone->compact_blockskip_flush = false;
@@ -2368,9 +2361,9 @@ __alloc_pages_direct_compact(struct alloc_info *ai, enum migrate_mode mode,
}
#else
static inline struct page *
-__alloc_pages_direct_compact(struct alloc_info *ai, enum migrate_mode mode,
- bool *contended_compaction, bool *deferred_compaction,
- unsigned long *did_some_progress)
+__alloc_pages_direct_compact(int alloc_flags, const struct alloc_info *ai,
+ enum migrate_mode mode, bool *contended_compaction,
+ bool *deferred_compaction, unsigned long *did_some_progress)
{
return NULL;
}
@@ -2406,12 +2399,11 @@ __perform_reclaim(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist,

/* The really slow allocator path where we enter direct reclaim */
static inline struct page *
-__alloc_pages_direct_reclaim(struct alloc_info *ai,
+__alloc_pages_direct_reclaim(int alloc_flags, const struct alloc_info *ai,
unsigned long *did_some_progress)
{
struct page *page = NULL;
bool drained = false;
- const int alloc_flags_saved = ai->alloc_flags;

*did_some_progress = __perform_reclaim(ai->gfp_mask, ai->order,
ai->zonelist, ai->nodemask);
@@ -2422,9 +2414,8 @@ __alloc_pages_direct_reclaim(struct alloc_info *ai,
if (IS_ENABLED(CONFIG_NUMA))
zlc_clear_zones_full(ai->zonelist);

- ai->alloc_flags &= ~ALLOC_NO_WATERMARKS;
retry:
- page = get_page_from_freelist(ai);
+ page = get_page_from_freelist(alloc_flags & ~ALLOC_NO_WATERMARKS, ai);

/*
* If an allocation failed after direct reclaim, it could be because
@@ -2436,7 +2427,6 @@ retry:
goto retry;
}

- ai->alloc_flags = alloc_flags_saved;
return page;
}

@@ -2445,21 +2435,18 @@ retry:
* sufficient urgency to ignore watermarks and take other desperate measures
*/
static inline struct page *
-__alloc_pages_high_priority(struct alloc_info *ai)
+__alloc_pages_high_priority(const struct alloc_info *ai)
{
struct page *page;
- const int alloc_flags_saved = ai->alloc_flags;

- ai->alloc_flags = ALLOC_NO_WATERMARKS;
do {
- page = get_page_from_freelist(ai);
+ page = get_page_from_freelist(ALLOC_NO_WATERMARKS, ai);

if (!page && ai->gfp_mask & __GFP_NOFAIL)
wait_iff_congested(ai->preferred_zone, BLK_RW_ASYNC,
HZ/50);
} while (!page && (ai->gfp_mask & __GFP_NOFAIL));

- ai->alloc_flags = alloc_flags_saved;
return page;
}

@@ -2591,15 +2578,12 @@ restart:

rebalance:
/* This is the last chance, in general, before the goto nopage. */
- ai->alloc_flags = alloc_flags & ~ALLOC_NO_WATERMARKS;
- page = get_page_from_freelist(ai);
+ page = get_page_from_freelist(alloc_flags & ~ALLOC_NO_WATERMARKS, ai);
if (page)
goto got_pg;

/* Allocate without watermarks if the context allows */
if (alloc_flags & ALLOC_NO_WATERMARKS) {
- /* We have removed ALLOC_NO_WATERMARKS from alloc_info */
- ai->alloc_flags = alloc_flags;
/*
* Ignore mempolicies if ALLOC_NO_WATERMARKS on the grounds
* the allocation is high priority and these type of
@@ -2637,7 +2621,7 @@ rebalance:
* Try direct compaction. The first pass is asynchronous. Subsequent
* attempts after direct reclaim are synchronous
*/
- page = __alloc_pages_direct_compact(ai, migration_mode,
+ page = __alloc_pages_direct_compact(alloc_flags, ai, migration_mode,
&contended_compaction,
&deferred_compaction,
&did_some_progress);
@@ -2664,7 +2648,7 @@ rebalance:
migration_mode = MIGRATE_SYNC_LIGHT;

/* Try direct reclaim and then allocating */
- page = __alloc_pages_direct_reclaim(ai, &did_some_progress);
+ page = __alloc_pages_direct_reclaim(alloc_flags, ai, &did_some_progress);
if (page)
goto got_pg;

@@ -2680,7 +2664,7 @@ rebalance:
if ((current->flags & PF_DUMPCORE) &&
!(gfp_mask & __GFP_NOFAIL))
goto nopage;
- page = __alloc_pages_may_oom(ai);
+ page = __alloc_pages_may_oom(alloc_flags, ai);
if (page)
goto got_pg;

@@ -2719,7 +2703,7 @@ rebalance:
* direct reclaim and reclaim/compaction depends on compaction
* being called after reclaim so call directly if necessary
*/
- page = __alloc_pages_direct_compact(ai, migration_mode,
+ page = __alloc_pages_direct_compact(alloc_flags, ai, migration_mode,
&contended_compaction,
&deferred_compaction,
&did_some_progress);
@@ -2747,9 +2731,9 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
struct zoneref *preferred_zoneref;
struct page *page = NULL;
unsigned int cpuset_mems_cookie;
+ int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET|ALLOC_FAIR;
struct alloc_info ai = {
.order = order,
- .alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET|ALLOC_FAIR,
.zonelist = zonelist,
.high_zoneidx = gfp_zone(gfp_mask),
.nodemask = nodemask,
@@ -2774,7 +2758,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
return NULL;

if (IS_ENABLED(CONFIG_CMA) && ai.migratetype == MIGRATE_MOVABLE)
- ai.alloc_flags |= ALLOC_CMA;
+ alloc_flags |= ALLOC_CMA;

retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
@@ -2789,7 +2773,7 @@ retry_cpuset:

/* First allocation attempt */
ai.gfp_mask = gfp_mask|__GFP_HARDWALL;
- page = get_page_from_freelist(&ai);
+ page = get_page_from_freelist(alloc_flags, &ai);
if (unlikely(!page)) {
/*
* Runtime PM, block IO and its error handling path
--
1.8.4.5

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