On Wed, 2023-06-21 at 11:36 +0530, Tarun Sahu wrote:
> Hi Alison,
>
> Alison Schofield <alison.schofi...@intel.com> writes:
>
> > On Tue, Jun 20, 2023 at 07:33:32PM +0530, Tarun Sahu wrote:
> > > memory_group_register_static takes maximum number of pages as the argument
> > > while dev_dax_kmem_probe passes total_len (in bytes) as the argument.
> >
> > This sounds like a fix. An explanation of the impact and a fixes tag
> > may be needed. Also, wondering how you found it.
> >
> Yes, it is a fix, I found it during dry code walk-through.
> There is not any impact as such. As,
> memory_group_register_static just set the max_pages limit which
> is used in auto_movable_zone_for_pfn to determine the zone.
>
> which might cause these condition to behave differently,
>
> This will be true always so jump will happen to kernel_zone
> if (!auto_movable_can_online_movable(NUMA_NO_NODE, group, nr_pages))
> goto kernel_zone;
> ---
> kernel_zone:
> return default_kernel_zone_for_pfn(nid, pfn, nr_pages);
>
> ---
>
> Here, In below, zone_intersects compare range will be larger as nr_pages
> will be higher (derived from total_len passed in dev_dax_kmem_probe).
>
> static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long
> start_pfn,
> unsigned long nr_pages)
> {
> struct pglist_data *pgdat = NODE_DATA(nid);
> int zid;
>
> for (zid = 0; zid < ZONE_NORMAL; zid++) {
> struct zone *zone = &pgdat->node_zones[zid];
>
> if (zone_intersects(zone, start_pfn, nr_pages))
> return zone;
> }
>
> return &pgdat->node_zones[ZONE_NORMAL];
> }
>
> In Mostly cases, ZONE_NORMAL will be returned. But there is no
> crash/panic issues involved here, only decision making on selecting zone
> is affected.
>
Hi Tarun,
Good find! With a Fixes tag, and perhaps inclusion of a bit more of
this detail described in the commit message, feel free to add:
Reviewed-by: Vishal Verma <vishal.l.ve...@intel.com>
