diff options
| author | David Rientjes | 2016-07-14 12:06:50 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2016-07-15 14:54:27 +0900 |
| commit | a46cbf3bc53b6a93fb84a5ffb288c354fa807954 (patch) | |
| tree | 9f9c1029e2291f6b366c881175f1a2894d246666 /mm/compaction.c | |
| parent | f97d10454e4da2aceb44dfa7c59bb43ba9f50199 (diff) | |
mm, compaction: prevent VM_BUG_ON when terminating freeing scanner
It's possible to isolate some freepages in a pageblock and then fail
split_free_page() due to the low watermark check. In this case, we hit
VM_BUG_ON() because the freeing scanner terminated early without a
contended lock or enough freepages.
This should never have been a VM_BUG_ON() since it's not a fatal
condition. It should have been a VM_WARN_ON() at best, or even handled
gracefully.
Regardless, we need to terminate anytime the full pageblock scan was not
done. The logic belongs in isolate_freepages_block(), so handle its
state gracefully by terminating the pageblock loop and making a note to
restart at the same pageblock next time since it was not possible to
complete the scan this time.
[rientjes@google.com: don't rescan pages in a pageblock]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1607111244150.83138@chino.kir.corp.google.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606291436300.145590@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Minchan Kim <minchan@kernel.org>
Tested-by: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Hugh Dickins <hughd@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: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/compaction.c')
| -rw-r--r-- | mm/compaction.c | 36 |
1 files changed, 14 insertions, 22 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index 79bfe0e06907..7bc04778f84d 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1009,8 +1009,6 @@ static void isolate_freepages(struct compact_control *cc) 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 * suitable migration targets, so periodically check if we need @@ -1034,36 +1032,30 @@ static void isolate_freepages(struct compact_control *cc) continue; /* Found a block suitable for isolating free pages from. */ - 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; + isolate_freepages_block(cc, &isolate_start_pfn, block_end_pfn, + freelist, false); /* - * If we isolated enough freepages, or aborted due to async - * compaction being contended, terminate the loop. - * Remember where the free scanner should restart next time, - * which is where isolate_freepages_block() left off. - * But if it scanned the whole pageblock, isolate_start_pfn - * now points at block_end_pfn, which is the start of the next - * pageblock. - * In that case we will however want to restart at the start - * of the previous pageblock. + * If we isolated enough freepages, or aborted due to lock + * contention, terminate. */ if ((cc->nr_freepages >= cc->nr_migratepages) || cc->contended) { - if (isolate_start_pfn >= block_end_pfn) + if (isolate_start_pfn >= block_end_pfn) { + /* + * Restart at previous pageblock if more + * freepages can be isolated next time. + */ isolate_start_pfn = block_start_pfn - pageblock_nr_pages; + } break; - } else { + } else if (isolate_start_pfn < block_end_pfn) { /* - * isolate_freepages_block() should not terminate - * prematurely unless contended, or isolated enough + * If isolation failed early, do not continue + * needlessly. */ - VM_BUG_ON(isolate_start_pfn < block_end_pfn); + break; } } |