Re: CMA broken in next-20120926

[Mel Gorman <mgorman@suse.de>]

On Tue, Oct 02, 2012 at 05:03:07PM +0200, Thierry Reding wrote:
> On Tue, Oct 02, 2012 at 03:41:35PM +0100, Mel Gorman wrote:
> > On Tue, Oct 02, 2012 at 02:48:14PM +0200, Thierry Reding wrote:
> > > > So this really isn't all that new, but I just wanted to confirm my
> > > > results from last week. We'll see if bisection shows up something
> > > > interesting.
> > > 
> > > I just finished bisecting this and git reports:
> > > 
> > > 	3750280f8bd0ed01753a72542756a8c82ab27933 is the first bad commit
> > > 
> > > I'm attaching the complete bisection log and a diff of all the changes
> > > applied on top of the bad commit to make it compile and run on my board.
> > > Most of the patch is probably not important, though. There are two hunks
> > > which have the pageblock changes I already posted an two other hunks
> > > with the patch you posted earlier.
> > > 
> > > I hope this helps. If you want me to run any other tests, please let me
> > > know.
> > > 
> > 
> > Can you test with this on top please?
> 
> That doesn't build on top of the bad commit. Or is it supposed to go on
> top of next-20120926?
> 

It doesn't build or do you mean it doesn't apply? Assuming the problem
was that it didn't apply then try this one. It applies on top of
next-20120928 which is the closest tag I have to next-20120926.

---8<---
mm: compaction: Cache if a pageblock was scanned and no pages were isolated -fix3

CMA requires that the PG_migrate_skip hint be skipped but it was only
skipping it when isolating pages for migration, not for free. Ensure
cc->isolate_skip_hint gets passed in both cases.

This is a fix for
mm-compaction-cache-if-a-pageblock-was-scanned-and-no-pages-were-isolated-fix.patch

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 mm/compaction.c |   16 ++++------------
 mm/internal.h   |    3 ++-
 mm/page_alloc.c |   26 +++++++++++++-------------
 3 files changed, 19 insertions(+), 26 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index f7a5ff5..62697fb 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -345,22 +345,14 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
  * a free page).
  */
 unsigned long
-isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn)
+isolate_freepages_range(struct compact_control *cc,
+			unsigned long start_pfn, unsigned long end_pfn)
 {
 	unsigned long isolated, pfn, block_end_pfn;
-	struct zone *zone = NULL;
 	LIST_HEAD(freelist);
 
-	/* cc needed for isolate_freepages_block to acquire zone->lock */
-	struct compact_control cc = {
-		.sync = true,
-	};
-
-	if (pfn_valid(start_pfn))
-		cc.zone = zone = page_zone(pfn_to_page(start_pfn));
-
 	for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) {
-		if (!pfn_valid(pfn) || zone != page_zone(pfn_to_page(pfn)))
+		if (!pfn_valid(pfn) || cc->zone != page_zone(pfn_to_page(pfn)))
 			break;
 
 		/*
@@ -370,7 +362,7 @@ isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn)
 		block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
 		block_end_pfn = min(block_end_pfn, end_pfn);
 
-		isolated = isolate_freepages_block(&cc, pfn, block_end_pfn,
+		isolated = isolate_freepages_block(cc, pfn, block_end_pfn,
 						   &freelist, true);
 
 		/*
diff --git a/mm/internal.h b/mm/internal.h
index f652660..4ea7497 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -131,7 +131,8 @@ struct compact_control {
 };
 
 unsigned long
-isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn);
+isolate_freepages_range(struct compact_control *cc,
+			unsigned long start_pfn, unsigned long end_pfn);
 unsigned long
 isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
 			   unsigned long low_pfn, unsigned long end_pfn);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e238fa34..6564e93 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5678,23 +5678,15 @@ __alloc_contig_migrate_alloc(struct page *page, unsigned long private,
 }
 
 /* [start, end) must belong to a single zone. */
-static int __alloc_contig_migrate_range(unsigned long start, unsigned long end)
+static int __alloc_contig_migrate_range(struct compact_control *cc,
+					unsigned long start, unsigned long end)
 {
 	/* This function is based on compact_zone() from compaction.c. */
 	unsigned long nr_reclaimed;
 	unsigned long pfn = start;
 	unsigned int tries = 0;
 	int ret = 0;
 
-	struct compact_control cc = {
-		.nr_migratepages = 0,
-		.order = -1,
-		.zone = page_zone(pfn_to_page(start)),
-		.sync = true,
-		.ignore_skip_hint = true,
-	};
-	INIT_LIST_HEAD(&cc.migratepages);
-
 	migrate_prep_local();
 
 	while (pfn < end || !list_empty(&cc.migratepages)) {
@@ -5803,6 +5794,15 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 	unsigned long outer_start, outer_end;
 	int ret = 0, order;
 
+	struct compact_control cc = {
+		.nr_migratepages = 0,
+		.order = -1,
+		.zone = page_zone(pfn_to_page(start)),
+		.sync = true,
+		.ignore_skip_hint = true,
+	};
+	INIT_LIST_HEAD(&cc.migratepages);
+
 	/*
 	 * What we do here is we mark all pageblocks in range as
 	 * MIGRATE_ISOLATE.  Because pageblock and max order pages may
@@ -5832,7 +5832,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 	if (ret)
 		goto done;
 
-	ret = __alloc_contig_migrate_range(start, end);
+	ret = __alloc_contig_migrate_range(cc, start, end);
 	if (ret)
 		goto done;
 
@@ -5881,7 +5881,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 	__reclaim_pages(zone, GFP_HIGHUSER_MOVABLE, end-start);
 
 	/* Grab isolated pages from freelists. */
-	outer_end = isolate_freepages_range(outer_start, end);
+	outer_end = isolate_freepages_range(cc, outer_start, end);
 	if (!outer_end) {
 		ret = -EBUSY;
 		goto done;

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