+ mm-compaction-abort-free-scanner-if-split-fails.patch added to -mm tree
From: akpm@linux-foundation.org
Date: 2016-06-22 21:51:29
Also in:
mm-commits
The patch titled
Subject: mm, compaction: abort free scanner if split fails
has been added to the -mm tree. Its filename is
mm-compaction-abort-free-scanner-if-split-fails.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-abort-free-scanner-if-split-fails.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-abort-free-scanner-if-split-fails.patch
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------------------------------------------------------
From: David Rientjes <rientjes@google.com>
Subject: mm, compaction: abort free scanner if split fails
If the memory compaction free scanner cannot successfully split a free
page (only possible due to per-zone low watermark), terminate the free
scanner rather than continuing to scan memory needlessly. If the
watermark is insufficient for a free page of order <= cc->order, then
terminate the scanner since all future splits will also likely fail.
This prevents the compaction freeing scanner from scanning all memory on
very large zones (very noticeable for zones > 128GB, for instance) when
all splits will likely fail while holding zone->lock.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606211820350.97086@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <redacted>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <redacted>
Cc: Mel Gorman <redacted>
Cc: Hugh Dickins <hughd@google.com>
Cc: <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/compaction.c | 39 +++++++++++++++++++++------------------
1 file changed, 21 insertions(+), 18 deletions(-)
diff -puN mm/compaction.c~mm-compaction-abort-free-scanner-if-split-fails mm/compaction.c--- a/mm/compaction.c~mm-compaction-abort-free-scanner-if-split-fails
+++ a/mm/compaction.c@@ -441,25 +441,23 @@ static unsigned long isolate_freepages_b /* Found a free page, break it into order-0 pages */ isolated = split_free_page(page); + if (!isolated) + break; + total_isolated += isolated; + cc->nr_freepages += isolated; for (i = 0; i < isolated; i++) { list_add(&page->lru, freelist); page++; } - - /* If a page was split, advance to the end of it */ - if (isolated) { - cc->nr_freepages += isolated; - if (!strict && - cc->nr_migratepages <= cc->nr_freepages) { - blockpfn += isolated; - break; - } - - blockpfn += isolated - 1; - cursor += isolated - 1; - continue; + if (!strict && cc->nr_migratepages <= cc->nr_freepages) { + blockpfn += isolated; + break; } + /* Advance to the end of split page */ + blockpfn += isolated - 1; + cursor += isolated - 1; + continue; isolate_fail: if (strict)
@@ -469,6 +467,9 @@ isolate_fail: } + if (locked) + spin_unlock_irqrestore(&cc->zone->lock, flags); + /* * There is a tiny chance that we have read bogus compound_order(), * so be careful to not go outside of the pageblock.
@@ -490,9 +491,6 @@ isolate_fail: if (strict && blockpfn < end_pfn) total_isolated = 0; - if (locked) - spin_unlock_irqrestore(&cc->zone->lock, flags); - /* Update the pageblock-skip if the whole pageblock was scanned */ if (blockpfn == end_pfn) update_pageblock_skip(cc, valid_page, total_isolated, false);
@@ -1011,6 +1009,7 @@ static void isolate_freepages(struct com block_end_pfn = block_start_pfn, block_start_pfn -= pageblock_nr_pages, isolate_start_pfn = block_start_pfn) { + unsigned long isolated; /* * This can iterate a massively long zone without finding any
@@ -1035,8 +1034,12 @@ static void isolate_freepages(struct com continue; /* Found a block suitable for isolating free pages from. */ - isolate_freepages_block(cc, &isolate_start_pfn, - block_end_pfn, freelist, false); + isolated = isolate_freepages_block(cc, &isolate_start_pfn, + block_end_pfn, freelist, false); + /* If isolation failed early, do not continue needlessly */ + if (!isolated && isolate_start_pfn < block_end_pfn && + cc->nr_migratepages > cc->nr_freepages) + break; /* * If we isolated enough freepages, or aborted due to async
_ Patches currently in -mm which might be from rientjes@google.com are mm-compaction-abort-free-scanner-if-split-fails.patch mm-compaction-split-freepages-without-holding-the-zone-lock-fix.patch