On Sun 05-12-21 22:33:37, Nico Pache wrote: > We shouldn't allocate pages on a unavailable node. Add a check for this > in __alloc_pages_node and return NULL to avoid issues further down the > callchain. > > Also update the VM_WARN_ON in __alloc_pages_node which could skip this > warn if the gfp_mask is not GFP_THISNODE. Page allocator trusts callers to know they are doing a right thing so that no unnecessary branches have to be implemented and the fast path is really optimized for performance. Allocating from an !node_online node is a bug in the caller. One that is not really that hard to make unfortunatelly but also one that is is not that common. That being said I am not really sure we want to introduce this check. > Co-developed-by: Rafael Aquini <aquini@xxxxxxxxxx> > Signed-off-by: Nico Pache <npache@xxxxxxxxxx> > --- > include/linux/gfp.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index b976c4177299..e7e18f6d0d9d 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -565,7 +565,10 @@ static inline struct page * > __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) > { > VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES); > - VM_WARN_ON((gfp_mask & __GFP_THISNODE) && !node_online(nid)); > + VM_WARN_ON(!node_online(nid)); > + > + if (!node_online(nid)) > + return NULL; > > return __alloc_pages(gfp_mask, order, nid, NULL); > } > -- > 2.33.1 -- Michal Hocko SUSE Labs