On 06/22/2018 06:28 PM, Michal Hocko wrote: > From: Michal Hocko <mhocko@xxxxxxxx> > > There is no real reason to blow up just because the caller doesn't know > that __get_free_pages cannot return highmem pages. Simply fix that up > silently. Even if we have some confused users such a fixup will not be > harmful. > > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> > --- > Hi Andrew, > previously posted [1] but it fell through cracks. Can we merge it now? > > [1] http://lkml.kernel.org/r/20171129160446.jluzpv3n6mjc3fwv@xxxxxxxxxxxxxx > > mm/page_alloc.c | 10 +++------- > 1 file changed, 3 insertions(+), 7 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 1521100f1e63..5f56f662a52d 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4402,18 +4402,14 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid, > EXPORT_SYMBOL(__alloc_pages_nodemask); > > /* > - * Common helper functions. > + * Common helper functions. Never use with __GFP_HIGHMEM because the returned > + * address cannot represent highmem pages. Use alloc_pages and then kmap if > + * you need to access high mem. > */ > unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order) > { > struct page *page; > > - /* > - * __get_free_pages() returns a virtual address, which cannot represent > - * a highmem page > - */ > - VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0); > - > page = alloc_pages(gfp_mask, order); The previous version had also replaced the line above with: + page = alloc_pages(gfp_mask & ~__GFP_HIGHMEM, order); This one doesn't, yet you say "fix that up silently". Bug? > if (!page) > return 0; >
