On Tue 26-06-18 15:57:39, Vlastimil Babka wrote: > 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? got lost somewhere on the way during the discussion. Thanks for spotting that. Andrew, could you add gfp_mask & ~__GFP_HIGHMEM please? Or should I resubmit? -- Michal Hocko SUSE Labs
