The patch titled
Subject: mm: compaction: Iron out isolate_freepages_block() and isolate_freepages_range()
has been added to the -mm tree. Its filename is
mm-compaction-acquire-the-zone-lock-as-late-as-possible-fix-2.patch
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From: Mel Gorman <mgorman@xxxxxxx>
Subject: mm: compaction: Iron out isolate_freepages_block() and isolate_freepages_range()
Andrew pointed out that isolate_freepages_block() is "straggly" and
isolate_freepages_range() is making assumptions on how compact_control is
used which is delicate. This patch straightens isolate_freepages_block()
and makes it fly straight and initialses compact_control to zeros in
isolate_freepages_range(). The code should be easier to follow and is
functionally equivalent. The CMA failure path is now a little more
expensive but that is a marginal corner-case.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Richard Davies <richard@xxxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxxxxxx>
Cc: Avi Kivity <avi@xxxxxxxxxx>
Cc: Rafael Aquini <aquini@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 48 +++++++++++++++++++++-------------------------
1 file changed, 22 insertions(+), 26 deletions(-)
diff -puN mm/compaction.c~mm-compaction-acquire-the-zone-lock-as-late-as-possible-fix-2 mm/compaction.c
--- a/mm/compaction.c~mm-compaction-acquire-the-zone-lock-as-late-as-possible-fix-2
+++ a/mm/compaction.c
@@ -96,7 +96,6 @@ static inline bool compact_trylock_irqsa
/* Returns true if the page is within a block suitable for migration to */
static bool suitable_migration_target(struct page *page)
{
-
int migratetype = get_pageblock_migratetype(page);
/* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
@@ -188,21 +187,20 @@ static unsigned long isolate_freepages_b
cursor = pfn_to_page(blockpfn);
- /* Isolate free pages. This assumes the block is valid */
+ /* Isolate free pages. */
for (; blockpfn < end_pfn; blockpfn++, cursor++) {
int isolated, i;
struct page *page = cursor;
- if (!pfn_valid_within(blockpfn))
- goto strict_check;
nr_scanned++;
-
+ if (!pfn_valid_within(blockpfn))
+ continue;
if (!PageBuddy(page))
- goto strict_check;
+ continue;
/*
- * The zone lock must be held to isolate freepages. This
- * unfortunately this is a very coarse lock and can be
+ * The zone lock must be held to isolate freepages.
+ * Unfortunately this is a very coarse lock and can be
* heavily contended if there are parallel allocations
* or parallel compactions. For async compaction do not
* spin on the lock and we acquire the lock as late as
@@ -219,12 +217,12 @@ static unsigned long isolate_freepages_b
/* Recheck this is a buddy page under lock */
if (!PageBuddy(page))
- goto strict_check;
+ continue;
/* Found a free page, break it into order-0 pages */
isolated = split_free_page(page);
if (!isolated && strict)
- goto strict_check;
+ break;
total_isolated += isolated;
for (i = 0; i < isolated; i++) {
list_add(&page->lru, freelist);
@@ -236,20 +234,18 @@ static unsigned long isolate_freepages_b
blockpfn += isolated - 1;
cursor += isolated - 1;
}
-
- continue;
-
-strict_check:
- /* Abort isolation if the caller requested strict isolation */
- if (strict) {
- total_isolated = 0;
- goto out;
- }
}
trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
-out:
+ /*
+ * If strict isolation is requested by CMA then check that all the
+ * pages scanned were isolated. If there were any failures, 0 is
+ * returned and CMA will fail.
+ */
+ if (strict && nr_scanned != total_isolated)
+ total_isolated = 0;
+
if (locked)
spin_unlock_irqrestore(&cc->zone->lock, flags);
@@ -275,14 +271,14 @@ isolate_freepages_range(unsigned long st
unsigned long isolated, pfn, block_end_pfn;
struct zone *zone = NULL;
LIST_HEAD(freelist);
- struct compact_control cc;
-
- if (pfn_valid(start_pfn))
- zone = page_zone(pfn_to_page(start_pfn));
/* cc needed for isolate_freepages_block to acquire zone->lock */
- cc.zone = zone;
- cc.sync = true;
+ 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)))
_
Patches currently in -mm which might be from mgorman@xxxxxxx are
mm-remove-__gfp_no_kswapd.patch
mm-compaction-update-comment-in-try_to_compact_pages.patch
mm-vmscan-scale-number-of-pages-reclaimed-by-reclaim-compaction-based-on-failures.patch
mm-vmscan-scale-number-of-pages-reclaimed-by-reclaim-compaction-based-on-failures-fix.patch
mm-compaction-capture-a-suitable-high-order-page-immediately-when-it-is-made-available.patch
revert-mm-mempolicy-let-vma_merge-and-vma_split-handle-vma-vm_policy-linkages.patch
mempolicy-remove-mempolicy-sharing.patch
mempolicy-fix-a-race-in-shared_policy_replace.patch
mempolicy-fix-refcount-leak-in-mpol_set_shared_policy.patch
mempolicy-fix-a-memory-corruption-by-refcount-imbalance-in-alloc_pages_vma.patch
mempolicy-fix-a-memory-corruption-by-refcount-imbalance-in-alloc_pages_vma-v2.patch
mm-cma-discard-clean-pages-during-contiguous-allocation-instead-of-migration.patch
mm-cma-discard-clean-pages-during-contiguous-allocation-instead-of-migration-fix.patch
mm-fix-tracing-in-free_pcppages_bulk.patch
mm-fix-tracing-in-free_pcppages_bulk-fix.patch
cma-fix-counting-of-isolated-pages.patch
cma-count-free-cma-pages.patch
cma-count-free-cma-pages-fix.patch
cma-fix-watermark-checking.patch
cma-fix-watermark-checking-fix.patch
mm-page_alloc-use-get_freepage_migratetype-instead-of-page_private.patch
mm-remain-migratetype-in-freed-page.patch
memory-hotplug-bug-fix-race-between-isolation-and-allocation.patch
memory-hotplug-fix-pages-missed-by-race-rather-than-failing.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long-fix.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long-fix-2.patch
mm-compaction-move-fatal-signal-check-out-of-compact_checklock_irqsave.patch
mm-compaction-update-try_to_compact_pageskerneldoc-comment.patch
mm-compaction-acquire-the-zone-lru_lock-as-late-as-possible.patch
mm-compaction-acquire-the-zone-lock-as-late-as-possible.patch
mm-compaction-acquire-the-zone-lock-as-late-as-possible-fix-2.patch
revert-mm-have-order-0-compaction-start-off-where-it-left.patch
mm-compaction-cache-if-a-pageblock-was-scanned-and-no-pages-were-isolated.patch
mm-compaction-restart-compaction-from-near-where-it-left-off.patch
mm-numa-reclaim-from-all-nodes-within-reclaim-distance.patch
mm-numa-reclaim-from-all-nodes-within-reclaim-distance-fix.patch
mm-thp-fix-pmd_present-for-split_huge_page-and-prot_none-with-thp.patch
mm-revert-0def08e3-mm-mempolicyc-check-return-code-of-check_range.patch
mm-revert-0def08e3-mm-mempolicyc-check-return-code-of-check_range-fix.patch
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