| Message ID | 20180719132740.32743-6-osalvador@techadventures.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu 19-07-18 15:27:40, osalvador@techadventures.net wrote: > From: Oscar Salvador <osalvador@suse.de> > > We should only care about deferred initialization when booting. Again why is this worth doing? > Signed-off-by: Oscar Salvador <osalvador@suse.de> > --- > mm/page_alloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d77bc2a7ec2c..5911b64a88ab 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6419,7 +6419,8 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size, > zones_size, zholes_size); > > alloc_node_mem_map(pgdat); > - pgdat_set_deferred_range(pgdat); > + if (system_state == SYSTEM_BOOTING) > + pgdat_set_deferred_range(pgdat); > > free_area_init_core(pgdat); > } > -- > 2.13.6 >
On Thu, Jul 19, 2018 at 03:46:22PM +0200, Michal Hocko wrote: > On Thu 19-07-18 15:27:40, osalvador@techadventures.net wrote: > > From: Oscar Salvador <osalvador@suse.de> > > > > We should only care about deferred initialization when booting. > > Again why is this worth doing? Well, it is not a big win if that is what you meant. Those two fields are only being used when dealing with deferred pages, which only happens at boot time. If later on, free_area_init_node gets called from memhotplug code, we will also set the fields, although they will not be used. Is this a problem? No, but I think it is more clear from the code if we see when this is called. So I would say it was only for code consistency. If you think this this is not worth, I am ok with dropping it. Thanks
On Thu 19-07-18 15:58:59, Oscar Salvador wrote: > On Thu, Jul 19, 2018 at 03:46:22PM +0200, Michal Hocko wrote: > > On Thu 19-07-18 15:27:40, osalvador@techadventures.net wrote: > > > From: Oscar Salvador <osalvador@suse.de> > > > > > > We should only care about deferred initialization when booting. > > > > Again why is this worth doing? > > Well, it is not a big win if that is what you meant. > > Those two fields are only being used when dealing with deferred pages, > which only happens at boot time. > > If later on, free_area_init_node gets called from memhotplug code, > we will also set the fields, although they will not be used. > > Is this a problem? No, but I think it is more clear from the code if we > see when this is called. > So I would say it was only for code consistency. Then put it to the changelog. > If you think this this is not worth, I am ok with dropping it. I am not really sure. I am not a big fan of SYSTEM_BOOTING global thingy so I would rather not spread its usage.
On Thu, Jul 19, 2018 at 10:03 AM Michal Hocko <mhocko@kernel.org> wrote: > > On Thu 19-07-18 15:58:59, Oscar Salvador wrote: > > On Thu, Jul 19, 2018 at 03:46:22PM +0200, Michal Hocko wrote: > > > On Thu 19-07-18 15:27:40, osalvador@techadventures.net wrote: > > > > From: Oscar Salvador <osalvador@suse.de> > > > > > > > > We should only care about deferred initialization when booting. > > > > > > Again why is this worth doing? > > > > Well, it is not a big win if that is what you meant. > > > > Those two fields are only being used when dealing with deferred pages, > > which only happens at boot time. > > > > If later on, free_area_init_node gets called from memhotplug code, > > we will also set the fields, although they will not be used. > > > > Is this a problem? No, but I think it is more clear from the code if we > > see when this is called. > > So I would say it was only for code consistency. > > Then put it to the changelog. > > > If you think this this is not worth, I am ok with dropping it. > > I am not really sure. I am not a big fan of SYSTEM_BOOTING global > thingy so I would rather not spread its usage. I agree, I do not think this patch is necessary. Calling pgdat_set_deferred_range() does not hurt in hotplug context, and it is cheap too. SYSTEM_BOOTING sometimes useful, but it is better to use it only where necessary, where without this "if" we will encounter some bugs. Thank you, Pavel
On Thu, Jul 19, 2018 at 10:27:44AM -0400, Pavel Tatashin wrote: > On Thu, Jul 19, 2018 at 10:03 AM Michal Hocko <mhocko@kernel.org> wrote: > > I am not really sure. I am not a big fan of SYSTEM_BOOTING global > > thingy so I would rather not spread its usage. > > I agree, I do not think this patch is necessary. Calling > pgdat_set_deferred_range() does not hurt in hotplug context, and it is > cheap too. SYSTEM_BOOTING sometimes useful, but it is better to use it > only where necessary, where without this "if" we will encounter some > bugs. Ok, let us drop it then ;-). Thanks
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d77bc2a7ec2c..5911b64a88ab 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6419,7 +6419,8 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size, zones_size, zholes_size); alloc_node_mem_map(pgdat); - pgdat_set_deferred_range(pgdat); + if (system_state == SYSTEM_BOOTING) + pgdat_set_deferred_range(pgdat); free_area_init_core(pgdat); }