Re: [netfilter-core] kernel panic: Out of memory and no killable processes... (2)

Dmitry Vyukov
2018-01-30T09:03:00Z

On Tue, Jan 30, 2018 at 9:28 AM, Kirill A. Shutemov
<kirill@shutemov.name> wrote:
> On Tue, Jan 30, 2018 at 09:11:27AM +0100, Florian Westphal wrote:
>> Michal Hocko <mhocko@kernel.org> wrote:
>> > On Mon 29-01-18 23:35:22, Florian Westphal wrote:
>> > > Kirill A. Shutemov <kirill@shutemov.name> 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.

I think we also need to consider setting up memory cgroup for
syzkaller test processes (we do RLIMIT_AS, but that's weak).