On 05/27/21 at 08:57pm, Liu Shixin wrote:
> The commit f63661566fad (mm/page_alloc.c: clear out zone->lowmem_reserve[]
> if the zone is empty) clear out zone->lowmem_reserve[] if zone is empty.
> But when zone is not empty and sysctl_lowmem_reserve_ratio[i] is set to zero,
> zone_managed_pages(zone) is not counted in the managed_pages either. This is
> inconsistent with the description of lowmen_reserve, so fix it.
Right, this is a good catch. Thanks for the fixing.
Is it worth adding words in Documentation/admin-guide/sysctl/vm.rst
to notice this?
Reviewed-by: Baoquan He <bhe@xxxxxxxxxx>
Thanks
Baoquan
>
> Fixes: f63661566fad ("mm/page_alloc.c: clear out zone->lowmem_reserve[] if the zone is empty")
> Reported-by: yangerkun <yangerkun@xxxxxxxxxx>
> Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
> ---
> mm/page_alloc.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index aaa1655cf682..49a2efce5a84 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8061,14 +8061,14 @@ static void setup_per_zone_lowmem_reserve(void)
> unsigned long managed_pages = 0;
>
> for (j = i + 1; j < MAX_NR_ZONES; j++) {
> - if (clear) {
> - zone->lowmem_reserve[j] = 0;
> - } else {
> - struct zone *upper_zone = &pgdat->node_zones[j];
> + struct zone *upper_zone = &pgdat->node_zones[j];
> +
> + managed_pages += zone_managed_pages(upper_zone);
>
> - managed_pages += zone_managed_pages(upper_zone);
> + if (clear)
> + zone->lowmem_reserve[j] = 0;
> + else
> zone->lowmem_reserve[j] = managed_pages / ratio;
> - }
> }
> }
> }
> --
> 2.18.0.huawei.25
>
>
