3.13.11.9 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Johannes Weiner <[email protected]> commit abe5f972912d086c080be4bde67750630b6fb38b upstream. The zone allocation batches can easily underflow due to higher-order allocations or spills to remote nodes. On SMP that's fine, because underflows are expected from concurrency and dealt with by returning 0. But on UP, zone_page_state will just return a wrapped unsigned long, which will get past the <= 0 check and then consider the zone eligible until its watermarks are hit. 3a025760fc15 ("mm: page_alloc: spill to remote nodes before waking kswapd") already made the counter-resetting use atomic_long_read() to accomodate underflows from remote spills, but it didn't go all the way with it. Make it clear that these batches are expected to go negative regardless of concurrency, and use atomic_long_read() everywhere. Fixes: 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy") Reported-by: Vlastimil Babka <[email protected]> Reported-by: Leon Romanovsky <[email protected]> Signed-off-by: Johannes Weiner <[email protected]> Acked-by: Mel Gorman <[email protected]> Signed-off-by: Andrew Morton <[email protected]> [ kamal: Johannes' 3.12 backport applied to 3.13-stable ] Signed-off-by: Kamal Mostafa <[email protected]> --- mm/page_alloc.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9aad4f1..38dca81 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1932,7 +1932,7 @@ zonelist_scan: if (alloc_flags & ALLOC_FAIR) { if (!zone_local(preferred_zone, zone)) continue; - if (zone_page_state(zone, NR_ALLOC_BATCH) <= 0) + if (atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]) <= 0) continue; } /* @@ -5599,9 +5599,8 @@ static void __setup_per_zone_wmarks(void) zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1); __mod_zone_page_state(zone, NR_ALLOC_BATCH, - high_wmark_pages(zone) - - low_wmark_pages(zone) - - zone_page_state(zone, NR_ALLOC_BATCH)); + high_wmark_pages(zone) - low_wmark_pages(zone) - + atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH])); setup_zone_migrate_reserve(zone); spin_unlock_irqrestore(&zone->lock, flags); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
