On Fri, Nov 01, 2019 at 03:57:18PM +0800, Huang, Ying wrote: > From: Huang Ying <ying.huang@xxxxxxxxx> > > When zone_watermark_ok() is called in migrate_balanced_pgdat() to > check migration target node, the parameter classzone_idx (for > requested zone) is specified as 0 (ZONE_DMA). But when allocating > memory for autonuma in alloc_misplaced_dst_page(), the requested zone > from GFP flags is ZONE_MOVABLE. That is, the requested zone is > different. The size of lowmem_reserve for the different requested > zone is different. And this may cause some issues. > > For example, in the zoneinfo of a test machine as below, > > Node 0, zone DMA32 > pages free 61592 > min 29 > low 454 > high 879 > spanned 1044480 > present 442306 > managed 425921 > protection: (0, 0, 62457, 62457, 62457) > > The free page number of ZONE_DMA32 is greater than "high watermark + > lowmem_reserve[ZONE_DMA]", but less than "high watermark + > lowmem_reserve[ZONE_MOVABLE]". And because __alloc_pages_node() in > alloc_misplaced_dst_page() requests ZONE_MOVABLE, the > zone_watermark_ok() on ZONE_DMA32 in migrate_balanced_pgdat() may > always return true. So, autonuma may not stop even when memory > pressure in node 0 is heavy. > > To fix the issue, ZONE_MOVABLE is used as parameter to call > zone_watermark_ok() in migrate_balanced_pgdat(). This makes it same > as requested zone in alloc_misplaced_dst_page(). So that > migrate_balanced_pgdat() returns false when memory pressure is heavy. > > Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxx> This patch is independent of the series and should be resent separately. Alternatively Andrew, please pick this patch up on its own. -- Mel Gorman SUSE Labs
