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
> if (pgdat->node_present_pages) {
> node_set_state(nid, N_MEMORY);
> check_for_memory(pgdat);
>
--
Sincerely yours,
Mike.
