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mm/compaction: correctly return failure with bogus compound_order in strict mode
In strict mode, we should return 0 if there is any hole in pageblock. If
we successfully isolated pages at beginning at pageblock and then have a
bogus compound_order outside pageblock in next page. We will abort search
loop with blockpfn > end_pfn. Although we will limit blockpfn to end_pfn,
we will treat it as a successful isolation in strict mode as blockpfn is
not < end_pfn and return partial isolated pages. Then
isolate_freepages_range may success unexpectly with hole in isolated
range.
Link: https://lkml.kernel.org/r/20230901155141.249860-4-shikemeng@huaweicloud.com
Fixes: 9fcd6d2e05
("mm, compaction: skip compound pages by order in free scanner")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
parent
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@ -626,11 +626,12 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
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if (PageCompound(page)) {
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const unsigned int order = compound_order(page);
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if (likely(order <= MAX_ORDER)) {
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if (blockpfn + (1UL << order) <= end_pfn) {
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blockpfn += (1UL << order) - 1;
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page += (1UL << order) - 1;
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nr_scanned += (1UL << order) - 1;
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}
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goto isolate_fail;
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}
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@ -678,8 +679,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
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spin_unlock_irqrestore(&cc->zone->lock, flags);
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/*
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* There is a tiny chance that we have read bogus compound_order(),
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* so be careful to not go outside of the pageblock.
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* Be careful to not go outside of the pageblock.
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*/
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if (unlikely(blockpfn > end_pfn))
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blockpfn = end_pfn;
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