Ohh, scratch that. The patch is bogus. I have completely missed that vmemmap_populate_hugepages already falls back to vmemmap_populate_basepages. I have to revisit the bug report I have received to see what happened apart from the allocation warning. Maybe we just want to silent that warning.
Sorry about the noise! On Tue 11-07-17 15:42:04, Michal Hocko wrote: > From: Michal Hocko <[email protected]> > > vmemmap_populate uses huge pages if the CPU supports them which is good > and usually what we want. vmemmap_alloc_block will use the bootmem > allocator in the early initialization so the allocation will most likely > succeed. This is not the case for the memory hotplug though. Such an > allocation can easily fail under memory pressure. Especially so when the > kernel memory is restricted with movable_node parameter. > > There is no real reason to fail the vmemmap_populate when > vmemmap_populate_hugepages fails though. We can still fallback to > vmemmap_populate_basepages and use base pages. The performance will not > be optimal but this is much better than failing the memory hot add. > > Signed-off-by: Michal Hocko <[email protected]> > --- > arch/x86/mm/init_64.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 136422d7d539..e6e3c755b9cb 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1401,15 +1401,16 @@ static int __meminit > vmemmap_populate_hugepages(unsigned long start, > int __meminit vmemmap_populate(unsigned long start, unsigned long end, int > node) > { > struct vmem_altmap *altmap = to_vmem_altmap(start); > - int err; > + int err = -ENOMEM; > > if (boot_cpu_has(X86_FEATURE_PSE)) > err = vmemmap_populate_hugepages(start, end, node, altmap); > else if (altmap) { > pr_err_once("%s: no cpu support for altmap allocations\n", > __func__); > - err = -ENOMEM; > - } else > + return err; > + } > + if (err) > err = vmemmap_populate_basepages(start, end, node); > if (!err) > sync_global_pgds(start, end - 1); > -- > 2.11.0 > -- Michal Hocko SUSE Labs
