Re: [PATCH v4 1/7] mm: page_alloc: avoid merging non-fallbackable pageblocks with others.
On Mon, Jan 24, 2022 at 11:12:07AM -0500, Zi Yan wrote:
> On 24 Jan 2022, at 9:02, Mel Gorman wrote:
>
> > On Wed, Jan 19, 2022 at 02:06:17PM -0500, Zi Yan wrote:
> >> From: Zi Yan
> >>
> >> This is done in addition to MIGRATE_ISOLATE pageblock merge avoidance.
> >> It prepares for the upcoming removal of the MAX_ORDER-1 alignment
> >> requirement for CMA and alloc_contig_range().
> >>
> >> MIGRARTE_HIGHATOMIC should not merge with other migratetypes like
> >> MIGRATE_ISOLATE and MIGRARTE_CMA[1], so this commit prevents that too.
> >> Also add MIGRARTE_HIGHATOMIC to fallbacks array for completeness.
> >>
> >> [1]
> >> https://lore.kernel.org/linux-mm/20211130100853.gp3...@techsingularity.net/
> >>
> >> Signed-off-by: Zi Yan
> >>
> >>
> >>
> >> @@ -2484,6 +2483,7 @@ static int fallbacks[MIGRATE_TYPES][3] = {
> >>[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,
> >> MIGRATE_TYPES },
> >>[MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,
> >> MIGRATE_TYPES },
> >>[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE,
> >> MIGRATE_TYPES },
> >> + [MIGRATE_HIGHATOMIC] = { MIGRATE_TYPES }, /* Never used */
> >> #ifdef CONFIG_CMA
> >>[MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */
> >> #endif
> >
> > If it's never used, why is it added?
>
> Just to make the fallbacks list complete, since MIGRATE_CMA and
> MIGRATE_ISOLATE are in the list. Instead, I can remove MIGRATE_CMA and
> MIGRATE_ISOLATE. WDYT?
>
It probably makes more sense to remove them or replace them with a comment
stating what migratetypes do not have a fallback list. Do it as a separate
patch that stands alone. It does not need to be part of this series.
--
Mel Gorman
SUSE Labs
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Re: [PATCH v4 1/7] mm: page_alloc: avoid merging non-fallbackable pageblocks with others.
On 24 Jan 2022, at 9:02, Mel Gorman wrote:
> On Wed, Jan 19, 2022 at 02:06:17PM -0500, Zi Yan wrote:
>> From: Zi Yan
>>
>> This is done in addition to MIGRATE_ISOLATE pageblock merge avoidance.
>> It prepares for the upcoming removal of the MAX_ORDER-1 alignment
>> requirement for CMA and alloc_contig_range().
>>
>> MIGRARTE_HIGHATOMIC should not merge with other migratetypes like
>> MIGRATE_ISOLATE and MIGRARTE_CMA[1], so this commit prevents that too.
>> Also add MIGRARTE_HIGHATOMIC to fallbacks array for completeness.
>>
>> [1]
>> https://lore.kernel.org/linux-mm/20211130100853.gp3...@techsingularity.net/
>>
>> Signed-off-by: Zi Yan
>>
>>
>>
>> @@ -2484,6 +2483,7 @@ static int fallbacks[MIGRATE_TYPES][3] = {
>> [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,
>> MIGRATE_TYPES },
>> [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,
>> MIGRATE_TYPES },
>> [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE,
>> MIGRATE_TYPES },
>> +[MIGRATE_HIGHATOMIC] = { MIGRATE_TYPES }, /* Never used */
>> #ifdef CONFIG_CMA
>> [MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */
>> #endif
>
> If it's never used, why is it added?
Just to make the fallbacks list complete, since MIGRATE_CMA and
MIGRATE_ISOLATE are in the list. Instead, I can remove MIGRATE_CMA and
MIGRATE_ISOLATE. WDYT?
>
> Otherwise looks fine so
>
> Acked-by: Mel Gorman
Thanks.
--
Best Regards,
Yan, Zi
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Re: [PATCH v4 1/7] mm: page_alloc: avoid merging non-fallbackable pageblocks with others.
On Wed, Jan 19, 2022 at 02:06:17PM -0500, Zi Yan wrote:
> From: Zi Yan
>
> This is done in addition to MIGRATE_ISOLATE pageblock merge avoidance.
> It prepares for the upcoming removal of the MAX_ORDER-1 alignment
> requirement for CMA and alloc_contig_range().
>
> MIGRARTE_HIGHATOMIC should not merge with other migratetypes like
> MIGRATE_ISOLATE and MIGRARTE_CMA[1], so this commit prevents that too.
> Also add MIGRARTE_HIGHATOMIC to fallbacks array for completeness.
>
> [1]
> https://lore.kernel.org/linux-mm/20211130100853.gp3...@techsingularity.net/
>
> Signed-off-by: Zi Yan
>
>
>
> @@ -2484,6 +2483,7 @@ static int fallbacks[MIGRATE_TYPES][3] = {
> [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,
> MIGRATE_TYPES },
> [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,
> MIGRATE_TYPES },
> [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE,
> MIGRATE_TYPES },
> + [MIGRATE_HIGHATOMIC] = { MIGRATE_TYPES }, /* Never used */
> #ifdef CONFIG_CMA
> [MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */
> #endif
If it's never used, why is it added?
Otherwise looks fine so
Acked-by: Mel Gorman
--
Mel Gorman
SUSE Labs
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[PATCH v4 1/7] mm: page_alloc: avoid merging non-fallbackable pageblocks with others.
From: Zi Yan
This is done in addition to MIGRATE_ISOLATE pageblock merge avoidance.
It prepares for the upcoming removal of the MAX_ORDER-1 alignment
requirement for CMA and alloc_contig_range().
MIGRARTE_HIGHATOMIC should not merge with other migratetypes like
MIGRATE_ISOLATE and MIGRARTE_CMA[1], so this commit prevents that too.
Also add MIGRARTE_HIGHATOMIC to fallbacks array for completeness.
[1] https://lore.kernel.org/linux-mm/20211130100853.gp3...@techsingularity.net/
Signed-off-by: Zi Yan
---
include/linux/mmzone.h | 11 +++
mm/page_alloc.c| 37 -
2 files changed, 31 insertions(+), 17 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index aed44e9b5d89..71b77aab748d 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -83,6 +83,17 @@ static inline bool is_migrate_movable(int mt)
return is_migrate_cma(mt) || mt == MIGRATE_MOVABLE;
}
+/*
+ * Check whether a migratetype can be merged with another migratetype.
+ *
+ * It is only mergeable when it can fall back to other migratetypes for
+ * allocation. See fallbacks[MIGRATE_TYPES][3] in page_alloc.c.
+ */
+static inline bool migratetype_is_mergeable(int mt)
+{
+ return mt < MIGRATE_PCPTYPES;
+}
+
#define for_each_migratetype_order(order, type) \
for (order = 0; order < MAX_ORDER; order++) \
for (type = 0; type < MIGRATE_TYPES; type++)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8dd6399bafb5..15de65215c02 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1117,25 +1117,24 @@ static inline void __free_one_page(struct page *page,
}
if (order < MAX_ORDER - 1) {
/* If we are here, it means order is >= pageblock_order.
-* We want to prevent merge between freepages on isolate
-* pageblock and normal pageblock. Without this, pageblock
-* isolation could cause incorrect freepage or CMA accounting.
+* We want to prevent merge between freepages on pageblock
+* without fallbacks and normal pageblock. Without this,
+* pageblock isolation could cause incorrect freepage or CMA
+* accounting or HIGHATOMIC accounting.
*
* We don't want to hit this code for the more frequent
* low-order merging.
*/
- if (unlikely(has_isolate_pageblock(zone))) {
- int buddy_mt;
+ int buddy_mt;
- buddy_pfn = __find_buddy_pfn(pfn, order);
- buddy = page + (buddy_pfn - pfn);
- buddy_mt = get_pageblock_migratetype(buddy);
+ buddy_pfn = __find_buddy_pfn(pfn, order);
+ buddy = page + (buddy_pfn - pfn);
+ buddy_mt = get_pageblock_migratetype(buddy);
- if (migratetype != buddy_mt
- && (is_migrate_isolate(migratetype) ||
- is_migrate_isolate(buddy_mt)))
- goto done_merging;
- }
+ if (migratetype != buddy_mt
+ && (!migratetype_is_mergeable(migratetype) ||
+ !migratetype_is_mergeable(buddy_mt)))
+ goto done_merging;
max_order = order + 1;
goto continue_merging;
}
@@ -2484,6 +2483,7 @@ static int fallbacks[MIGRATE_TYPES][3] = {
[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,
MIGRATE_TYPES },
[MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,
MIGRATE_TYPES },
[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE,
MIGRATE_TYPES },
+ [MIGRATE_HIGHATOMIC] = { MIGRATE_TYPES }, /* Never used */
#ifdef CONFIG_CMA
[MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */
#endif
@@ -2795,8 +2795,8 @@ static void reserve_highatomic_pageblock(struct page
*page, struct zone *zone,
/* Yoink! */
mt = get_pageblock_migratetype(page);
- if (!is_migrate_highatomic(mt) && !is_migrate_isolate(mt)
- && !is_migrate_cma(mt)) {
+ /* Only reserve normal pageblocks (i.e., they can merge with others) */
+ if (migratetype_is_mergeable(mt)) {
zone->nr_reserved_highatomic += pageblock_nr_pages;
set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);
@@ -3545,8 +3545,11 @@ int __isolate_free_page(struct page *page, unsigned int
order)
struct page *endpage = page + (1 << order) - 1;
for (; page < endpage; page += pageblock_nr_pages) {
int mt = get_pageblock_migratetype(page);
- if (!is_migrate_isolate(mt) &&
