Re: [Qemu-devel] [PATCH] linux-user: do setrlimit selectively

[Peter Maydell]

On 4 September 2018 at 23:26, Max Filippov <address@hidden> wrote:
> On Tue, Sep 4, 2018 at 3:10 PM, Peter Maydell <address@hidden> wrote:
>> On 4 September 2018 at 23:02, Max Filippov <address@hidden> wrote:

>> You could make a case for always ignoring setrlimit calls: if we
>> ever hit the limit it's as likely to be by failing a QEMU internal
>> allocation as a guest one, so not to imposing the limit at all
>> would avoid QEMU failing then. But that would apply in both the
>> 32-on-64 and also 32-on-32 and 64-on-64 cases too.
>
> That's what I did initially, but it feels somewhat unsafe in 64-on-64 case.
> My expectation is that limits set by 64-bit guest should be somewhat
> suitable for the 64-bit host, is it wrong?

It doesn't matter what the limit the guest sets is -- the
problem is that if we hit it then chances are good it'll cause
a QEMU allocation to fail and then we'll deadlock. The limit
might be entirely reasonable for the guest program (which
presumably has a plan for handling the failure) but QEMU
itself can't cope with hitting the limit.

https://bugs.launchpad.net/qemu/+bug/1163034 is the bug I
mentioned in my earlier email, by the way.

thanks
-- PMM