Messages in this thread | | | Date | Fri, 25 Sep 2020 09:42:15 +0200 | From | Michal Hocko <> | Subject | Re: [v3 1/2] mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged |
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On Wed 16-09-20 18:21:48, Vijay Balakrishna wrote: > When memory is hotplug added or removed the min_free_kbytes must be > recalculated based on what is expected by khugepaged. Currently > after hotplug, min_free_kbytes will be set to a lower default and higher > default set when THP enabled is lost. This change restores min_free_kbytes > as expected for THP consumers. > > Fixes: f000565adb77 ("thp: set recommended min free kbytes") > > Signed-off-by: Vijay Balakrishna <vijayb@linux.microsoft.com> > Cc: stable@vger.kernel.org > Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
I am ok with this patch. I am not sure this is worth backporting to stable trees becasuse this is not a functional bug. Surprising behavior, yes, but not much more than that.
Acked-by: Michal Hocko <mhocko@suse.com>
One minor comment below [...] > @@ -857,6 +858,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, > zone_pcp_update(zone); > > init_per_zone_wmark_min(); > + khugepaged_min_free_kbytes_update(); > > kswapd_run(nid); > kcompactd_run(nid); > @@ -1600,6 +1602,7 @@ static int __ref __offline_pages(unsigned long start_pfn, > pgdat_resize_unlock(zone->zone_pgdat, &flags); > > init_per_zone_wmark_min(); > + khugepaged_min_free_kbytes_update(); > > if (!populated_zone(zone)) { > zone_pcp_reset(zone);
Can we move khugepaged_min_free_kbytes_update into init_per_zone_wmark_min? If it stays external we might hit the same problem when somebody else needs to modify min_free_kbytes. Early init call will be likely too early for khugepaged but that shouldn't matter AFAICS because it will call khugepaged_min_free_kbytes_update on its own. -- Michal Hocko SUSE Labs
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