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author | NARIBAYASHI Akira <a.naribayashi@fujitsu.com> | 2022-10-26 14:24:38 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-14 12:16:27 +0300 |
commit | 882734bbc5873143b17292cd29504bda9142d565 (patch) | |
tree | bede0283cb43c206fb6785c7115364d91f9c7603 /mm/compaction.c | |
parent | ae7793027766491c5f8635b12d15a5940d3b8698 (diff) | |
download | linux-882734bbc5873143b17292cd29504bda9142d565.tar.xz |
mm, compaction: fix fast_isolate_around() to stay within boundaries
commit be21b32afe470c5ae98e27e49201158a47032942 upstream.
Depending on the memory configuration, isolate_freepages_block() may scan
pages out of the target range and causes panic.
Panic can occur on systems with multiple zones in a single pageblock.
The reason it is rare is that it only happens in special
configurations. Depending on how many similar systems there are, it
may be a good idea to fix this problem for older kernels as well.
The problem is that pfn as argument of fast_isolate_around() could be out
of the target range. Therefore we should consider the case where pfn <
start_pfn, and also the case where end_pfn < pfn.
This problem should have been addressd by the commit 6e2b7044c199 ("mm,
compaction: make fast_isolate_freepages() stay within zone") but there was
an oversight.
Case1: pfn < start_pfn
<at memory compaction for node Y>
| node X's zone | node Y's zone
+-----------------+------------------------------...
pageblock ^ ^ ^
+-----------+-----------+-----------+-----------+...
^ ^ ^
^ ^ end_pfn
^ start_pfn = cc->zone->zone_start_pfn
pfn
<---------> scanned range by "Scan After"
Case2: end_pfn < pfn
<at memory compaction for node X>
| node X's zone | node Y's zone
+-----------------+------------------------------...
pageblock ^ ^ ^
+-----------+-----------+-----------+-----------+...
^ ^ ^
^ ^ pfn
^ end_pfn
start_pfn
<---------> scanned range by "Scan Before"
It seems that there is no good reason to skip nr_isolated pages just after
given pfn. So let perform simple scan from start to end instead of
dividing the scan into "Before" and "After".
Link: https://lkml.kernel.org/r/20221026112438.236336-1-a.naribayashi@fujitsu.com
Fixes: 6e2b7044c199 ("mm, compaction: make fast_isolate_freepages() stay within zone").
Signed-off-by: NARIBAYASHI Akira <a.naribayashi@fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/compaction.c')
-rw-r--r-- | mm/compaction.c | 18 |
1 files changed, 5 insertions, 13 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index 8dfbe86bd74f..b58021666e1a 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1245,7 +1245,7 @@ move_freelist_tail(struct list_head *freelist, struct page *freepage) } static void -fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long nr_isolated) +fast_isolate_around(struct compact_control *cc, unsigned long pfn) { unsigned long start_pfn, end_pfn; struct page *page; @@ -1266,21 +1266,13 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long if (!page) return; - /* Scan before */ - if (start_pfn != pfn) { - isolate_freepages_block(cc, &start_pfn, pfn, &cc->freepages, 1, false); - if (cc->nr_freepages >= cc->nr_migratepages) - return; - } - - /* Scan after */ - start_pfn = pfn + nr_isolated; - if (start_pfn < end_pfn) - isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false); + isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false); /* Skip this pageblock in the future as it's full or nearly full */ if (cc->nr_freepages < cc->nr_migratepages) set_pageblock_skip(page); + + return; } /* Search orders in round-robin fashion */ @@ -1456,7 +1448,7 @@ fast_isolate_freepages(struct compact_control *cc) return cc->free_pfn; low_pfn = page_to_pfn(page); - fast_isolate_around(cc, low_pfn, nr_isolated); + fast_isolate_around(cc, low_pfn); return low_pfn; } |