Messages in this thread |  | | Date | Fri, 27 Mar 2020 20:18:20 -0300 | From | Jason Gunthorpe <> | Subject | Re: [Patch v2 2/2] mm/page_alloc.c: define node_order with all zero |
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On Fri, Mar 27, 2020 at 03:37:57PM -0700, John Hubbard wrote: > On 3/27/20 3:01 PM, Wei Yang wrote: > > Since we always clear node_order before getting it, we can leverage > > compiler to do this instead of at run time. > > > > Signed-off-by: Wei Yang <richard.weiyang@gmail.com> > > mm/page_alloc.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index dfcf2682ed40..49dd1f25c000 100644 > > +++ b/mm/page_alloc.c > > @@ -5585,7 +5585,7 @@ static void build_thisnode_zonelists(pg_data_t *pgdat) > > static void build_zonelists(pg_data_t *pgdat) > > { > > - static int node_order[MAX_NUMNODES]; > > + static int node_order[MAX_NUMNODES] = {0}; > > > Looks wrong: now the single instance of node_order is initialized just once by > the compiler. And that means that only the first caller of this function > gets a zeroed node_order array...
It is also redundant, all static data is 0 initialized in Linux and should not be explicitly initialized so it can remain in .bss
> > @@ -5595,7 +5595,6 @@ static void build_zonelists(pg_data_t *pgdat) > > load = nr_online_nodes; > > prev_node = local_node; > > - memset(node_order, 0, sizeof(node_order)); > > ...and all subsequent callers are left with whatever debris is remaining in > node_order. So this is not good.
Indeed
Jason
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