On Wed, 20 Jul 2016, Vlastimil Babka wrote: > >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >> index eb1968a1041e..30443804f156 100644 > >> --- a/mm/page_alloc.c > >> +++ b/mm/page_alloc.c > >> @@ -3541,35 +3541,42 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned > >> int order, > >> */ > >> alloc_flags = gfp_to_alloc_flags(gfp_mask); > >> > >> + if (gfp_mask & __GFP_KSWAPD_RECLAIM) > >> + wake_all_kswapds(order, ac); > >> + > >> + /* > >> + * The adjusted alloc_flags might result in immediate success, so try > >> + * that first > >> + */ > >> + page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac); > >> + if (page) > >> + goto got_pg; > > > > Any reason to not test gfp_pfmemalloc_allowed() here? For contexts where > > it returns true, it seems like the above would be an unneeded failure if > > ALLOC_WMARK_MIN would have failed. No strong opinion. > > Yeah, two reasons: > 1 - less overhead (for the test) if we went to slowpath just to wake up > kswapd and then succeed on min watermark > 2 - try all zones with min watermark before resorting to no watermark > (if allowed), so we don't needlessly put below min watermark the first > zone in zonelist, while some later zone would still be above watermark >
The second point makes sense, thanks! Acked-by: David Rientjes <rient...@google.com>
