The patch titled
Subject: mm/compaction: fix edge case of fast_find_migrateblock()
has been added to the -mm tree. Its filename is
mm-compactoin-fix-edge-case-of-fast_find_migrateblock.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-compactoin-fix-edge-case-of-fast_find_migrateblock.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-compactoin-fix-edge-case-of-fast_find_migrateblock.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Wonhyuk Yang <vvghjk1234@xxxxxxxxx>
Subject: mm/compaction: fix edge case of fast_find_migrateblock()
In the fast_find_migrateblock(), It iterate freelist to find proper
pageblock. But there are two edge cases. First, if the page we found is
equal to cc->migrate_pfn, it is considered that we didn't found suitable
pageblock. Second, if the loop was terminated because order is less than
PAGE_ALLOC_COSTLY_ORDER, it could be considered that we found suitable
one.
Link: https://lkml.kernel.org/r/20210123154320.24278-1-vvghjk1234@xxxxxxxxx
Fixes: 70b44595eafe9 ("mm, compaction: use free lists to quickly locate a migration source")
Signed-off-by: Wonhyuk Yang <vvghjk1234@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <Vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/mm/compaction.c~mm-compactoin-fix-edge-case-of-fast_find_migrateblock
+++ a/mm/compaction.c
@@ -1739,8 +1739,8 @@ static unsigned long fast_find_migratebl
distance >>= 2;
high_pfn = pageblock_start_pfn(cc->migrate_pfn + distance);
- for (order = cc->order - 1;
- order >= PAGE_ALLOC_COSTLY_ORDER && pfn == cc->migrate_pfn && nr_scanned < limit;
+ for (order = cc->order - 1, pfn = high_pfn;
+ order >= PAGE_ALLOC_COSTLY_ORDER && pfn == high_pfn && nr_scanned < limit;
order--) {
struct free_area *area = &cc->zone->free_area[order];
struct list_head *freelist;
@@ -1782,7 +1782,6 @@ static unsigned long fast_find_migratebl
}
if (nr_scanned >= limit) {
- cc->fast_search_fail++;
move_freelist_tail(freelist, freepage);
break;
}
@@ -1796,9 +1795,10 @@ static unsigned long fast_find_migratebl
* If fast scanning failed then use a cached entry for a page block
* that had free pages as the basis for starting a linear scan.
*/
- if (pfn == cc->migrate_pfn)
+ if (pfn == high_pfn) {
+ cc->fast_search_fail++;
pfn = reinit_migrate_pfn(cc);
-
+ }
return pfn;
}
_
Patches currently in -mm which might be from vvghjk1234@xxxxxxxxx are
mm-compactoin-fix-edge-case-of-fast_find_migrateblock.patch
