Hi, > On Sep 27, 2023, at 06:37, Shawn Anastasio <[email protected]> > wrote: > > When building for Power with CONFIG_DEBUG unset, a compiler error gets > raised inside page_alloc.c's node_to_scrub function: > > common/page_alloc.c: In function 'node_to_scrub.part.0': > common/page_alloc.c:1217:29: error: array subscript 1 is above array > bounds of 'long unsigned int[1]' [-Werror=array-bounds] > 1217 | if ( node_need_scrub[node] ) > > It appears that this is a false positive, given that in practice > cycle_node should never return a node ID >= MAX_NUMNODES as long as the > architecture's node_online_map is properly defined and initialized, so > this additional bounds check is only to satisfy GCC. > > Signed-off-by: Shawn Anastasio <[email protected]> > Reviewed-by: Stefano Stabellini <[email protected]>
I am seeing some discussions going on about this patch, but once this is patch is ready for merge please feel free to add: Release-acked-by: Henry Wang <[email protected]> Kind regards, Henry > --- > v2: Add comment to explain the bounds check. > > xen/common/page_alloc.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c > index 35d9a26fa6..9b5df74fdd 100644 > --- a/xen/common/page_alloc.c > +++ b/xen/common/page_alloc.c > @@ -1211,6 +1211,14 @@ static unsigned int node_to_scrub(bool get_node) > } while ( !cpumask_empty(&node_to_cpumask(node)) && > (node != local_node) ); > > + /* > + * In practice `node` will always be within MAX_NUMNODES, but GCC > can't > + * always see that, so an explicit check is necessary to avoid > tripping > + * its out-of-bounds array access warning (-Warray-bounds). > + */ > + if ( node >= MAX_NUMNODES ) > + break; > + > if ( node == local_node ) > break; > > -- > 2.30.2 > >
