On Tue 10-10-17 23:13:21, Tetsuo Handa wrote: > Michal Hocko wrote: > > On Tue 10-10-17 21:47:02, Tetsuo Handa wrote: > > > I think that massive vmalloc() consumers should be (as well as massive > > > alloc_page() consumers) careful such that they will be chosen as first OOM > > > victim, for vmalloc() does not abort as soon as an OOM occurs. > > > > No. This would require to spread those checks all over the place. That > > is why we have that logic inside the allocator which fails the > > allocation at certain point in time. Large/unbound/user controlled sized > > allocations from the kernel are always a bug and really hard one to > > protect from. It is simply impossible to know the intention. > > > > > Thus, I used > > > set_current_oom_origin()/clear_current_oom_origin() when I demonstrated > > > "complete" depletion. > > > > which was a completely artificial example as already mentioned. > > > > > > I have tried to explain this is not really needed before but you keep > > > > insisting which is highly annoying. The patch as is is not harmful but > > > > it is simply _pointless_ IMHO. > > > > > > Then, how can massive vmalloc() consumers become careful? > > > Explicitly use __vmalloc() and pass __GFP_NOMEMALLOC ? > > > Then, what about adding some comment like "Never try to allocate large > > > memory using plain vmalloc(). Use __vmalloc() with __GFP_NOMEMALLOC." ? > > > > Come on! Seriously we do expect some competence from the code running in > > the kernel space. We do not really need to add a comment that you > > shouldn't shoot your head because it might hurt. Please try to focus on > > real issues. There are many of them to chase after... > > > My understanding is that vmalloc() is provided for allocating large memory > where kmalloc() is difficult to satisfy. If we say "do not allocate large > memory with vmalloc() because large allocations from the kernel are always > a bug", it sounds like denial of raison d'etre of vmalloc(). Strange... try to find some middle ground between literal following the wording and a common sense. In kernel anything larger than order-3 is a large allocation. The large we are arguing here is MBs of memory. -- 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>
