On 07.04.22 14:45, David Hildenbrand wrote:
On 07.04.22 14:06, Juergen Gross wrote:Since commit 6aa303defb74 ("mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator") only zones with free memory are included in a built zonelist. This is problematic when e.g. all memory of a zone has been ballooned out when zonelists are being rebuilt. The decision whether to rebuild the zonelists when onlining new memory is done based on populated_zone() returning 0 for the zone the memory will be added to. The new zone is added to the zonelists only, if it has free memory pages (managed_zone() returns a non-zero value) after the memory has been onlined. This implies, that onlining memory will always free the added pages to the allocator immediately, but this is not true in all cases: when e.g. running as a Xen guest the onlined new memory will be added only to the ballooned memory list, it will be freed only when the guest is being ballooned up afterwards. Another problem with using managed_zone() for the decision whether a zone is being added to the zonelists is, that a zone with all memory used will in fact be removed from all zonelists in case the zonelists happen to be rebuilt. Use populated_zone() when building a zonelist as it has been done before that commit. Cc: stable@xxxxxxxxxxxxxxx Fixes: 6aa303defb74 ("mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator") Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> --- V2: - updated commit message (Michal Hocko) --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index bdc8f60ae462..3d0662af3289 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6128,7 +6128,7 @@ static int build_zonerefs_node(pg_data_t *pgdat, struct zoneref *zonerefs) do { zone_type--; zone = pgdat->node_zones + zone_type; - if (managed_zone(zone)) { + if (populated_zone(zone)) { zoneref_set_zone(zone, &zonerefs[nr_zones++]); check_highest_zone(zone_type); }Did you drop my Ack?
Oh, sorry for that.
Also, I'd appreciate getting CCed on patches where I commented.
Will do in future. Juergen
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