On Thu 31-03-16 20:56:23, Tetsuo Handa wrote: > Michal Hocko wrote: > > On Wed 30-03-16 20:46:48, Tetsuo Handa wrote: > > > Michal Hocko wrote: > > > > On Tue 29-03-16 15:13:54, David Rientjes wrote: > > > > > On Tue, 29 Mar 2016, Michal Hocko wrote: > > > > > > > > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > > > > > index 86349586eacb..1c2b7a82f0c4 100644 > > > > > > --- a/mm/oom_kill.c > > > > > > +++ b/mm/oom_kill.c > > > > > > @@ -876,6 +876,10 @@ bool out_of_memory(struct oom_control *oc) > > > > > > return true; > > > > > > } > > > > > > > > > > > > + /* The OOM killer does not compensate for IO-less reclaim. */ > > > > > > + if (!(oc->gfp_mask & __GFP_FS)) > > > > > > + return true; > > > > > > + > > > > > > This patch will disable pagefault_out_of_memory() because currently > > > pagefault_out_of_memory() is passing oc->gfp_mask == 0. > > > > > > Because of current behavior, calling oom notifiers from !__GFP_FS seems > > > to be safe. > > > > You are right! I have completely missed that and thought we were > > providing GFP_KERNEL there. So we have two choices. Either we do > > use GFP_KERNEL (same as we do for sysrq+f) or we special case > > pagefault_out_of_memory in some way. The second option seems to be safer > > because the gfp_mask has to contain at least ___GFP_DIRECT_RECLAIM to > > trigger the OOM path. > > Oops, I missed that this patch also disables out_of_memory() for !__GFP_FS && > __GFP_NOFAIL allocation requests. True. The following should take care of that: diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 54aa4ec06889..32d8210b8773 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -882,7 +882,7 @@ bool out_of_memory(struct oom_control *oc) * make sure exclude 0 mask - all other users should have at least * ___GFP_DIRECT_RECLAIM to get here. */ - if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS)) + if (oc->gfp_mask && !(oc->gfp_mask & (__GFP_FS|__GFP_NOFAIL))) return true; /* Thanks for spotting this! [...] -- Michal Hocko SUSE Labs -- 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>