[Sorry for the late reply] On Mon 22-10-12 16:34:15, Glauber Costa wrote: > On 10/20/2012 12:34 AM, David Rientjes wrote: > > On Fri, 19 Oct 2012, Glauber Costa wrote: > > > >>>>> What about gfp & __GFP_FS? > >>>>> > >>>> > >>>> Do you intend to prevent or allow OOM under that flag? I personally > >>>> think that anything that accepts to be OOM-killed should have GFP_WAIT > >>>> set, so that ought to be enough. > >>>> > >>> > >>> The oom killer in the page allocator cannot trigger without __GFP_FS > >>> because direct reclaim has little chance of being very successful and > >>> thus we end up needlessly killing processes, and that tends to happen > >>> quite a bit if we dont check for it. Seems like this would also happen > >>> with memcg if mem_cgroup_reclaim() has a large probability of failing? > >>> > >> > >> I can indeed see tests for GFP_FS in some key locations in mm/ before > >> calling the OOM Killer. > >> > >> Should I test for GFP_IO as well? > > > > It's not really necessary, if __GFP_IO isn't set then it wouldn't make > > sense for __GFP_FS to be set. > > > >> If the idea is preventing OOM to > >> trigger for allocations that can write their pages back, how would you > >> feel about the following test: > >> > >> may_oom = (gfp & GFP_KERNEL) && !(gfp & __GFP_NORETRY) ? > >> > > > > I would simply copy the logic from the page allocator and only trigger oom > > for __GFP_FS and !__GFP_NORETRY. > > > > That seems reasonable to me. Michal ? Yes it makes sense to be consistent with the global case. While we are at it, do we need to consider PF_DUMPCORE resp. !__GFP_NOFAIL? -- 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>