KAMEZAWA Hiroyuki wrote:
On Thu, 23 Feb 2012 17:52:56 +0400
Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx> wrote:
Prepare for lru_lock splitting in memory compaction code.
* disable irqs in acct_isolated() for __mod_zone_page_state(),
lru_lock isn't required there.
Signed-off-by: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
---
mm/compaction.c | 30 ++++++++++++++++--------------
1 files changed, 16 insertions(+), 14 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index a976b28..54340e4 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -224,8 +224,10 @@ static void acct_isolated(struct zone *zone, struct compact_control *cc)
list_for_each_entry(page,&cc->migratepages, lru)
count[!!page_is_file_cache(page)]++;
+ local_irq_disable();
__mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
__mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
+ local_irq_enable();
Why we need to disable Irq here ??
__mod_zone_page_state() want this to protect per-cpu counters, maybe preempt_disable() is enough.
}
/* Similar to reclaim, but different enough that they don't share logic */
@@ -262,7 +264,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
unsigned long nr_scanned = 0, nr_isolated = 0;
struct list_head *migratelist =&cc->migratepages;
isolate_mode_t mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE;
- struct lruvec *lruvec;
+ struct lruvec *lruvec = NULL;
/* Do not scan outside zone boundaries */
low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
@@ -294,25 +296,24 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
/* Time to isolate some pages for migration */
cond_resched();
- spin_lock_irq(&zone->lru_lock);
for (; low_pfn< end_pfn; low_pfn++) {
struct page *page;
- bool locked = true;
/* give a chance to irqs before checking need_resched() */
if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) {
- spin_unlock_irq(&zone->lru_lock);
- locked = false;
+ if (lruvec)
+ unlock_lruvec_irq(lruvec);
+ lruvec = NULL;
}
- if (need_resched() || spin_is_contended(&zone->lru_lock)) {
- if (locked)
- spin_unlock_irq(&zone->lru_lock);
+ if (need_resched() ||
+ (lruvec&& spin_is_contended(&zone->lru_lock))) {
+ if (lruvec)
+ unlock_lruvec_irq(lruvec);
+ lruvec = NULL;
cond_resched();
- spin_lock_irq(&zone->lru_lock);
if (fatal_signal_pending(current))
break;
- } else if (!locked)
- spin_lock_irq(&zone->lru_lock);
+ }
/*
* migrate_pfn does not necessarily start aligned to a
@@ -359,7 +360,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
continue;
}
- if (!PageLRU(page))
+ if (!__lock_page_lruvec_irq(&lruvec, page))
continue;
Could you add more comments onto __lock_page_lruvec_irq() ?
Actually there is a very unlikely race with page free-realloc,
(which is fixed in Hugh's patchset, and surprisingly fixed in my old memory controller)
thus this part will be redesigned.
Thanks,
-Kame
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