The patch titled
Subject: mm/compaction: correctly return failure with bogus compound_order in strict mode
has been added to the -mm mm-unstable branch. Its filename is
mm-compaction-correctly-return-failure-with-bogus-compound_order-in-strict-mode.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-compaction-correctly-return-failure-with-bogus-compound_order-in-strict-mode.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Subject: mm/compaction: correctly return failure with bogus compound_order in strict mode
Date: Fri, 1 Sep 2023 23:51:38 +0800
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@xxxxxxxxxxxxxxx
Fixes: 9fcd6d2e052e ("mm, compaction: skip compound pages by order in free scanner")
Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/compaction.c~mm-compaction-correctly-return-failure-with-bogus-compound_order-in-strict-mode
+++ a/mm/compaction.c
@@ -626,11 +626,12 @@ static unsigned long isolate_freepages_b
if (PageCompound(page)) {
const unsigned int order = compound_order(page);
- if (likely(order <= MAX_ORDER)) {
+ if (blockpfn + (1UL << order) <= end_pfn) {
blockpfn += (1UL << order) - 1;
page += (1UL << order) - 1;
nr_scanned += (1UL << order) - 1;
}
+
goto isolate_fail;
}
@@ -678,8 +679,7 @@ isolate_fail:
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.
+ * Be careful to not go outside of the pageblock.
*/
if (unlikely(blockpfn > end_pfn))
blockpfn = end_pfn;
_
Patches currently in -mm which might be from shikemeng@xxxxxxxxxxxxxxx are
mm-compaction-use-correct-list-in-move_freelist_head-tail.patch
mm-compaction-call-list_is_first-last-more-intuitively-in-move_freelist_head-tail.patch
mm-compaction-correctly-return-failure-with-bogus-compound_order-in-strict-mode.patch
mm-compaction-remove-repeat-compact_blockskip_flush-check-in-reset_isolation_suitable.patch
mm-compaction-improve-comment-of-is_via_compact_memory.patch
mm-compaction-factor-out-code-to-test-if-we-should-run-compaction-for-target-order.patch
