On Sat, Feb 16, 2019 at 6:02 AM Baoquan He <b...@redhat.com> wrote: > > Size of struct page might be larger than 64 bytes if debug options > enabled, or fields added for debugging intentionally. Yet an upper > limit need be added at build time to trigger an alert in case the > size is too big to boot up system, warning people to check if it's > be done on purpose in advance. > > Here 1/4 of PAGE_SIZE is chosen since system must have been insane > with this value. For those systems with PAGE_SIZE larger than 4KB, > 1KB is simply taken. > > Signed-off-by: Baoquan He <b...@redhat.com> > --- > mm/page_alloc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 35fdde041f5c..eb6c8e22333b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -67,6 +67,7 @@ > #include <linux/lockdep.h> > #include <linux/nmi.h> > #include <linux/psi.h> > +#include <linux/sizes.h> > > #include <asm/sections.h> > #include <asm/tlbflush.h> > @@ -7084,6 +7085,7 @@ void __init free_area_init_nodes(unsigned long > *max_zone_pfn) > unsigned long start_pfn, end_pfn; > int i, nid; > > + BUILD_BUG_ON(sizeof(struct page) > min_t(size_t, SZ_1K, PAGE_SIZE));
Are there systems with PAGE_SIZE < 1K? Maybe this should just be a direct SZ_1K check? (Also, perhaps this should use the new static_assert where struct page is defined?) -Kees > /* Record where the zone boundaries are */ > memset(arch_zone_lowest_possible_pfn, 0, > sizeof(arch_zone_lowest_possible_pfn)); > -- > 2.17.2 > -- Kees Cook
