On Sat, 21 Jan 2017 12:01:26 +0800 kbuild test robot <fengguang.wu@xxxxxxxxx> wrote: > tree: git://git.cmpxchg.org/linux-mmotm.git master > head: fa78008f505569e7988ed3eb737ca7d43d87eac3 > commit: 6f387b30fdba17b62b7c13d67d3caebbcc3bef0c [159/293] mm: consolidate GFP_NOFAIL checks in the allocator slowpath > config: i386-allmodconfig (attached as .config) > compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901 > reproduce: > git checkout 6f387b30fdba17b62b7c13d67d3caebbcc3bef0c > # save the attached .config to linux build tree > make ARCH=i386 > > Note: it may well be a FALSE warning. FWIW you are at least aware of it now. > http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings > > All warnings (new ones prefixed by >>): > > mm/page_alloc.c: In function '__alloc_pages_slowpath': > >> mm/page_alloc.c:3546:15: warning: 'alloc_flags' may be used uninitialized in this function [-Wmaybe-uninitialized] > unsigned int alloc_flags; > ^~~~~~~~~~~ Yup. I guess we initialize alloc_flags before the `goto nopage'. --- a/mm/page_alloc.c~mm-consolidate-gfp_nofail-checks-in-the-allocator-slowpath-fix +++ a/mm/page_alloc.c @@ -3577,6 +3577,14 @@ retry_cpuset: no_progress_loops = 0; compact_priority = DEF_COMPACT_PRIORITY; cpuset_mems_cookie = read_mems_allowed_begin(); + + /* + * The fast path uses conservative alloc_flags to succeed only until + * kswapd needs to be woken up, and to avoid the cost of setting up + * alloc_flags precisely. So we do that now. + */ + alloc_flags = gfp_to_alloc_flags(gfp_mask); + /* * We need to recalculate the starting point for the zonelist iterator * because we might have used different nodemask in the fast path, or @@ -3588,14 +3596,6 @@ retry_cpuset: if (!ac->preferred_zoneref->zone) goto nopage; - - /* - * The fast path uses conservative alloc_flags to succeed only until - * kswapd needs to be woken up, and to avoid the cost of setting up - * alloc_flags precisely. So we do that now. - */ - alloc_flags = gfp_to_alloc_flags(gfp_mask); - if (gfp_mask & __GFP_KSWAPD_RECLAIM) wake_all_kswapds(order, ac); _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
