On 04/09/24 at 06:40pm, Mike Rapoport wrote:
> On Thu, Apr 04, 2024 at 11:23:51AM +0800, Baoquan He wrote:
> > On 04/02/24 at 11:32am, Mike Rapoport wrote:
> > > On Tue, Mar 26, 2024 at 02:11:28PM +0800, Baoquan He wrote:
> > > > Because memory-less node's ->node_present_pages and its
> > > > zone's ->present_pages are all 0, the judgement before calling
> > > > node_set_state() to set N_MEMORY, N_HIGH_MEMORY, N_NORMAL_MEMORY for
> > > > node is enough to skip memory-less node. The 'continue;' statement
> > > > inside for_each_node() loop of free_area_init() is gilding the lily.
> > > >
> > > > Here, remove the special handling to make memory-less node share the
> > > > same code flow as normal node. And the code comment above the 'continue'
> > > > statement is not needed either.
> > > >
> > > > Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
> > > > ---
> > > > mm/mm_init.c | 18 +++---------------
> > > > 1 file changed, 3 insertions(+), 15 deletions(-)
> > > >
> > > > diff --git a/mm/mm_init.c b/mm/mm_init.c
> > > > index 089dc60159e9..99681ffb9091 100644
> > > > --- a/mm/mm_init.c
> > > > +++ b/mm/mm_init.c
> > > > @@ -1834,28 +1834,16 @@ void __init free_area_init(unsigned long *max_zone_pfn)
> > > > panic("Cannot allocate %zuB for node %d.\n",
> > > > sizeof(*pgdat), nid);
> > > > arch_refresh_nodedata(nid, pgdat);
> > > > - free_area_init_node(nid);
> > > > -
> > > > - /*
> > > > - * We do not want to confuse userspace by sysfs
> > > > - * files/directories for node without any memory
> > > > - * attached to it, so this node is not marked as
> > > > - * N_MEMORY and not marked online so that no sysfs
> > > > - * hierarchy will be created via register_one_node for
> > > > - * it. The pgdat will get fully initialized by
> > > > - * hotadd_init_pgdat() when memory is hotplugged into
> > > > - * this node.
> > > > - */
> > >
> > > I think this comment is still valuable. Maybe rephrase it a bit and move it
> > > before 'if (pgdat->node_present_pages)'?
> >
> > Fair enough.
> >
> > Do you think below paragraph is OK to you? Please help polish or
> > rephrase it.
> >
> > diff --git a/mm/mm_init.c b/mm/mm_init.c
> > index dd875f943cbb..3ce0f29637ba 100644
> > --- a/mm/mm_init.c
> > +++ b/mm/mm_init.c
> > @@ -1839,7 +1839,14 @@ void __init free_area_init(unsigned long *max_zone_pfn)
> > pgdat = NODE_DATA(nid);
> > free_area_init_node(nid);
> >
> > - /* Any memory on that node */
> > + /*
> > + * No sysfs hierarcy will be created via register_one_node()
> > + *for memory-less node because here it's not marked as N_MEMORY
> > + *and won't be set online later. The benefit is userspace
> > + *program won't be confused by sysfs files/directories of
> > + *memory-less node. The pgdat will get fully initialized by
> > + *hotadd_init_pgdat() when memory is hotplugged into this node.
> > + */
>
> Ack
Thanks a lot for reviewing and confirming, Mike.
Hi Andrew,
I have sent out v2 to include above code comment changing, please feel
free to pick the draft patch and append, or take the newly post v2.
Thanks.
>
> > if (pgdat->node_present_pages) {
> > node_set_state(nid, N_MEMORY);
> > check_for_memory(pgdat);
> >
>
> --
> Sincerely yours,
> Mike.
>
