[PATCH] mm: __alloc_pages cleanup
Clean up of __alloc_pages.
Restoration of previous behaviour, plus further cleanups by introducing an
'alloc_flags', removing the last of should_reclaim_zone.
Signed-off-by: Rohit Seth <rohit.seth@intel.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b37dc0f..845b917 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -732,9 +732,7 @@
}
local_irq_restore(flags);
put_cpu();
- }
-
- if (page == NULL) {
+ } else {
spin_lock_irqsave(&zone->lock, flags);
page = __rmqueue(zone, order);
spin_unlock_irqrestore(&zone->lock, flags);
@@ -754,20 +752,25 @@
return page;
}
+#define ALLOC_NO_WATERMARKS 0x01 /* don't check watermarks at all */
+#define ALLOC_HARDER 0x02 /* try to alloc harder */
+#define ALLOC_HIGH 0x04 /* __GFP_HIGH set */
+#define ALLOC_CPUSET 0x08 /* check for correct cpuset */
+
/*
* Return 1 if free pages are above 'mark'. This takes into account the order
* of the allocation.
*/
int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
- int classzone_idx, int can_try_harder, gfp_t gfp_high)
+ int classzone_idx, int alloc_flags)
{
/* free_pages my go negative - that's OK */
long min = mark, free_pages = z->free_pages - (1 << order) + 1;
int o;
- if (gfp_high)
+ if (alloc_flags & ALLOC_HIGH)
min -= min / 2;
- if (can_try_harder)
+ if (alloc_flags & ALLOC_HARDER)
min -= min / 4;
if (free_pages <= min + z->lowmem_reserve[classzone_idx])
@@ -785,14 +788,40 @@
return 1;
}
-static inline int
-should_reclaim_zone(struct zone *z, gfp_t gfp_mask)
+/*
+ * get_page_from_freeliest goes through the zonelist trying to allocate
+ * a page.
+ */
+static struct page *
+get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
+ struct zonelist *zonelist, int alloc_flags)
{
- if (!z->reclaim_pages)
- return 0;
- if (gfp_mask & __GFP_NORECLAIM)
- return 0;
- return 1;
+ struct zone **z = zonelist->zones;
+ struct page *page = NULL;
+ int classzone_idx = zone_idx(*z);
+
+ /*
+ * Go through the zonelist once, looking for a zone with enough free.
+ * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+ */
+ do {
+ if ((alloc_flags & ALLOC_CPUSET) &&
+ !cpuset_zone_allowed(*z, gfp_mask))
+ continue;
+
+ if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
+ if (!zone_watermark_ok(*z, order, (*z)->pages_low,
+ classzone_idx, alloc_flags))
+ continue;
+ }
+
+ page = buffered_rmqueue(*z, order, gfp_mask);
+ if (page) {
+ zone_statistics(zonelist, *z);
+ break;
+ }
+ } while (*(++z) != NULL);
+ return page;
}
/*
@@ -803,92 +832,60 @@
struct zonelist *zonelist)
{
const gfp_t wait = gfp_mask & __GFP_WAIT;
- struct zone **zones, *z;
+ struct zone **z;
struct page *page;
struct reclaim_state reclaim_state;
struct task_struct *p = current;
- int i;
- int classzone_idx;
int do_retry;
- int can_try_harder;
+ int alloc_flags;
int did_some_progress;
might_sleep_if(wait);
- /*
- * The caller may dip into page reserves a bit more if the caller
- * cannot run direct reclaim, or is the caller has realtime scheduling
- * policy
- */
- can_try_harder = (unlikely(rt_task(p)) && !in_interrupt()) || !wait;
+ z = zonelist->zones; /* the list of zones suitable for gfp_mask */
- zones = zonelist->zones; /* the list of zones suitable for gfp_mask */
-
- if (unlikely(zones[0] == NULL)) {
+ if (unlikely(*z == NULL)) {
/* Should this ever happen?? */
return NULL;
}
-
- classzone_idx = zone_idx(zones[0]);
-
restart:
+ page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order,
+ zonelist, ALLOC_CPUSET);
+ if (page)
+ goto got_pg;
+
+ do
+ wakeup_kswapd(*z, order);
+ while (*(++z));
+
/*
- * Go through the zonelist once, looking for a zone with enough free.
- * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+ * OK, we're below the kswapd watermark and have kicked background
+ * reclaim. Now things get more complex, so set up alloc_flags according
+ * to how we want to proceed.
+ *
+ * The caller may dip into page reserves a bit more if the caller
+ * cannot run direct reclaim, or if the caller has realtime scheduling
+ * policy.
*/
- for (i = 0; (z = zones[i]) != NULL; i++) {
- int do_reclaim = should_reclaim_zone(z, gfp_mask);
-
- if (!cpuset_zone_allowed(z, __GFP_HARDWALL))
- continue;
-
- /*
- * If the zone is to attempt early page reclaim then this loop
- * will try to reclaim pages and check the watermark a second
- * time before giving up and falling back to the next zone.
- */
-zone_reclaim_retry:
- if (!zone_watermark_ok(z, order, z->pages_low,
- classzone_idx, 0, 0)) {
- if (!do_reclaim)
- continue;
- else {
- zone_reclaim(z, gfp_mask, order);
- /* Only try reclaim once */
- do_reclaim = 0;
- goto zone_reclaim_retry;
- }
- }
-
- page = buffered_rmqueue(z, order, gfp_mask);
- if (page)
- goto got_pg;
- }
-
- for (i = 0; (z = zones[i]) != NULL; i++)
- wakeup_kswapd(z, order);
+ alloc_flags = 0;
+ if ((unlikely(rt_task(p)) && !in_interrupt()) || !wait)
+ alloc_flags |= ALLOC_HARDER;
+ if (gfp_mask & __GFP_HIGH)
+ alloc_flags |= ALLOC_HIGH;
+ if (wait)
+ alloc_flags |= ALLOC_CPUSET;
/*
* Go through the zonelist again. Let __GFP_HIGH and allocations
- * coming from realtime tasks to go deeper into reserves
+ * coming from realtime tasks go deeper into reserves.
*
* This is the last chance, in general, before the goto nopage.
* Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
* See also cpuset_zone_allowed() comment in kernel/cpuset.c.
*/
- for (i = 0; (z = zones[i]) != NULL; i++) {
- if (!zone_watermark_ok(z, order, z->pages_min,
- classzone_idx, can_try_harder,
- gfp_mask & __GFP_HIGH))
- continue;
-
- if (wait && !cpuset_zone_allowed(z, gfp_mask))
- continue;
-
- page = buffered_rmqueue(z, order, gfp_mask);
- if (page)
- goto got_pg;
- }
+ page = get_page_from_freelist(gfp_mask, order, zonelist, alloc_flags);
+ if (page)
+ goto got_pg;
/* This allocation should allow future memory freeing. */
@@ -897,13 +894,10 @@
if (!(gfp_mask & __GFP_NOMEMALLOC)) {
nofail_alloc:
/* go through the zonelist yet again, ignoring mins */
- for (i = 0; (z = zones[i]) != NULL; i++) {
- if (!cpuset_zone_allowed(z, gfp_mask))
- continue;
- page = buffered_rmqueue(z, order, gfp_mask);
- if (page)
- goto got_pg;
- }
+ page = get_page_from_freelist(gfp_mask, order,
+ zonelist, ALLOC_NO_WATERMARKS|ALLOC_CPUSET);
+ if (page)
+ goto got_pg;
if (gfp_mask & __GFP_NOFAIL) {
blk_congestion_wait(WRITE, HZ/50);
goto nofail_alloc;
@@ -924,7 +918,7 @@
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
- did_some_progress = try_to_free_pages(zones, gfp_mask);
+ did_some_progress = try_to_free_pages(zonelist->zones, gfp_mask);
p->reclaim_state = NULL;
p->flags &= ~PF_MEMALLOC;
@@ -932,19 +926,10 @@
cond_resched();
if (likely(did_some_progress)) {
- for (i = 0; (z = zones[i]) != NULL; i++) {
- if (!zone_watermark_ok(z, order, z->pages_min,
- classzone_idx, can_try_harder,
- gfp_mask & __GFP_HIGH))
- continue;
-
- if (!cpuset_zone_allowed(z, gfp_mask))
- continue;
-
- page = buffered_rmqueue(z, order, gfp_mask);
- if (page)
- goto got_pg;
- }
+ page = get_page_from_freelist(gfp_mask, order,
+ zonelist, alloc_flags);
+ if (page)
+ goto got_pg;
} else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
/*
* Go through the zonelist yet one more time, keep
@@ -952,18 +937,10 @@
* a parallel oom killing, we must fail if we're still
* under heavy pressure.
*/
- for (i = 0; (z = zones[i]) != NULL; i++) {
- if (!zone_watermark_ok(z, order, z->pages_high,
- classzone_idx, 0, 0))
- continue;
-
- if (!cpuset_zone_allowed(z, __GFP_HARDWALL))
- continue;
-
- page = buffered_rmqueue(z, order, gfp_mask);
- if (page)
- goto got_pg;
- }
+ page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order,
+ zonelist, ALLOC_CPUSET);
+ if (page)
+ goto got_pg;
out_of_memory(gfp_mask, order);
goto restart;
@@ -996,9 +973,7 @@
dump_stack();
show_mem();
}
- return NULL;
got_pg:
- zone_statistics(zonelist, z);
return page;
}