On Tue 30-01-18 10:02:34, Dmitry Vyukov wrote: > On Tue, Jan 30, 2018 at 9:28 AM, Kirill A. Shutemov > <kirill@xxxxxxxxxxxxx> wrote: > > On Tue, Jan 30, 2018 at 09:11:27AM +0100, Florian Westphal wrote: > >> Michal Hocko <mhocko@xxxxxxxxxx> wrote: > >> > On Mon 29-01-18 23:35:22, Florian Westphal wrote: > >> > > Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote: > >> > [...] > >> > > > I hate what I'm saying, but I guess we need some tunable here. > >> > > > Not sure what exactly. > >> > > > >> > > Would memcg help? > >> > > >> > That really depends. I would have to check whether vmalloc path obeys > >> > __GFP_ACCOUNT (I suspect it does except for page tables allocations but > >> > that shouldn't be a big deal). But then the other potential problem is > >> > the life time of the xt_table_info (or other potentially large) data > >> > structures. Are they bound to any process life time. > >> > >> No. > > > > Well, IIUC they bound to net namespace life time, so killing all > > proccesses in the namespace would help to get memory back. :) > > ... unless the namespace is mounted into file system. > > Let's start with NOWARN as that's what kernel generally uses for > allocations with user-controllable size. ENOMEM is roughly as > informative as the WARNING message in this case. You want __GFP_NORETRY but that is not _fully_ supported by kvmalloc right now. More specifically kvmalloc doesn't guanratee that the request will not trigger the OOM killer (like regular __GFP_NORETRY). This is because of internal vmalloc restrictions. If you are however OK to simply bail out in most cases then __GFP_NORETRY should work reasonably fine. > I think we also need to consider setting up memory cgroup for > syzkaller test processes (we do RLIMIT_AS, but that's weak). Well, this is not about syzkaller, it merely pointed out a potential DoS... And that has to be addressed somehow. -- 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>
