On Fri, May 29, 2020 at 09:06:09AM +0800, Feng Tang wrote: > As is explained by Michal Hocko: > > : Looking at the history, this has been added by 82f71ae4a2b8 > : ("mm: catch memory commitment underflow") to have a safety check > : for issues which have been fixed. There doesn't seem to be any bug > : reports mentioning this splat since then so it is likely just > : spending cycles for a hot path (yes many people run with DEBUG_VM) > : without a strong reason.
Hmm, it looks like the warning is still useful to catch issues in, https://lore.kernel.org/linux-mm/20140624201606.18273.44270.stgit@zurg https://lore.kernel.org/linux-mm/54bb9a32.7080...@oracle.com/ After read the whole discussion in that thread, I actually disagree with Michal. In order to get ride of this existing warning, it is rather someone needs a strong reason that could prove the performance hit is noticeable with some data. > > Signed-off-by: Feng Tang <feng.t...@intel.com> > Cc: Konstantin Khlebnikov <koc...@gmail.com> > Cc: Qian Cai <c...@lca.pw> > Cc: Michal Hocko <mho...@suse.com> > Cc: Andi Kleen <andi.kl...@intel.com> > --- > mm/util.c | 8 -------- > 1 file changed, 8 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 3c7a08c..fe63271 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -814,14 +814,6 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, > int cap_sys_admin) > { > long allowed; > > - /* > - * A transient decrease in the value is unlikely, so no need > - * READ_ONCE() for vm_committed_as.count. > - */ > - VM_WARN_ONCE(data_race(percpu_counter_read(&vm_committed_as) < > - -(s64)vm_committed_as_batch * num_online_cpus()), > - "memory commitment underflow"); > - > vm_acct_memory(pages); > > /* > -- > 2.7.4 >