On Mon, 26 Feb 2018, Aaron Lu wrote: > Matthew Wilcox found that all callers of free_pcppages_bulk() currently > update pcp->count immediately after so it's natural to do it inside > free_pcppages_bulk(). > > No functionality or performance change is expected from this patch. > > Suggested-by: Matthew Wilcox <wi...@infradead.org> > Signed-off-by: Aaron Lu <aaron...@intel.com> > --- > mm/page_alloc.c | 10 +++------- > 1 file changed, 3 insertions(+), 7 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cb416723538f..3154859cccd6 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1117,6 +1117,7 @@ static void free_pcppages_bulk(struct zone *zone, int > count, > int batch_free = 0; > bool isolated_pageblocks; > > + pcp->count -= count; > spin_lock(&zone->lock); > isolated_pageblocks = has_isolate_pageblock(zone); >
Why modify pcp->count before the pages have actually been freed? I doubt that it matters too much, but at least /proc/zoneinfo uses zone->lock. I think it should be done after the lock is dropped. Otherwise, looks good.
