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[PATCH] mm: __alloc_pages cleanup
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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>
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Rohit Seth authored and Linus Torvalds committed Nov 14, 2005
1 parent 51c6f66 commit 7fb1d9f
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Showing 3 changed files with 89 additions and 114 deletions.
2 changes: 1 addition & 1 deletion include/linux/mmzone.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -329,7 +329,7 @@ void get_zone_counts(unsigned long *active, unsigned long *inactive,
void build_all_zonelists(void);
void wakeup_kswapd(struct zone *zone, int order);
int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
int alloc_type, int can_try_harder, gfp_t gfp_high);
int classzone_idx, int alloc_flags);

#ifdef CONFIG_HAVE_MEMORY_PRESENT
void memory_present(int nid, unsigned long start, unsigned long end);
Expand Down
195 changes: 85 additions & 110 deletions mm/page_alloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -732,9 +732,7 @@ buffered_rmqueue(struct zone *zone, int order, gfp_t gfp_flags)
}
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);
Expand All @@ -754,20 +752,25 @@ buffered_rmqueue(struct zone *zone, int order, gfp_t gfp_flags)
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])
Expand All @@ -785,14 +788,40 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
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;
}

/*
Expand All @@ -803,92 +832,60 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order,
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;

zones = zonelist->zones; /* the list of zones suitable for gfp_mask */
z = 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;
}
restart:
page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order,
zonelist, ALLOC_CPUSET);
if (page)
goto got_pg;

classzone_idx = zone_idx(zones[0]);
do
wakeup_kswapd(*z, order);
while (*(++z));

restart:
/*
* 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. */

Expand All @@ -897,13 +894,10 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order,
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;
Expand All @@ -924,46 +918,29 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order,
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;

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
* very high watermark here, this is only to catch
* 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;
Expand Down Expand Up @@ -996,9 +973,7 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order,
dump_stack();
show_mem();
}
return NULL;
got_pg:
zone_statistics(zonelist, z);
return page;
}

Expand Down
6 changes: 3 additions & 3 deletions mm/vmscan.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1074,7 +1074,7 @@ static int balance_pgdat(pg_data_t *pgdat, int nr_pages, int order)
continue;

if (!zone_watermark_ok(zone, order,
zone->pages_high, 0, 0, 0)) {
zone->pages_high, 0, 0)) {
end_zone = i;
goto scan;
}
Expand Down Expand Up @@ -1111,7 +1111,7 @@ static int balance_pgdat(pg_data_t *pgdat, int nr_pages, int order)

if (nr_pages == 0) { /* Not software suspend */
if (!zone_watermark_ok(zone, order,
zone->pages_high, end_zone, 0, 0))
zone->pages_high, end_zone, 0))
all_zones_ok = 0;
}
zone->temp_priority = priority;
Expand Down Expand Up @@ -1259,7 +1259,7 @@ void wakeup_kswapd(struct zone *zone, int order)
return;

pgdat = zone->zone_pgdat;
if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0, 0))
if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0))
return;
if (pgdat->kswapd_max_order < order)
pgdat->kswapd_max_order = order;
Expand Down

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