[LTP] [PATCH] mem/lib: keep allocating memory until get an error in single process

[Li Wang]

On Mon, Jun 20, 2016 at 09:03:51AM -0400, Jan Stancek wrote:
> > 
> > 2. The child_alloc() probably should also do memory allocation with an
> > infinite loop
> 
> At the time 'lite' was introduced, everything was single threaded,
> the only difference was that lite == 0 would keep allocating in
> infinite loop.
> 
> Your patch is effectively eliminating lite == 1, which means that
> oom03 will pass even if cgroup limits are broken.

You're right! My previous meothod didn't solve the essential problem.

> 
> > in single process mode. Because if someone has a caller testoom(0, 1, ENOMEM,
> > 1) at other
> > place in future, that'll be easily get fauilures.
> 
> Likely because author is expecting behaviour other than what
> we have now:
> 
>  * @lite: if non-zero, child makes only single TESTMEM+MB allocation
>  *        if zero, child keeps allocating memory until it gets killed
>  *        or some operation fails

Okay, now just keep it this way.

> 
> > Or, can we solve them in one method?
> 
> We could skip oom(KSM) if lite == 1 in testoom(), since limit_in_bytes
> may vary from run to run, which isn't reliable for oom03 cgroup test.
> 
> Or we could change alloc_mem for lite == 1 && testcase == KSM,
> such that each page would have unique content (to prevent merging).

Yes, and we clould also keep the KSM scan off while lite == 1.
	if (lite != 1) SAFE_FILE_PRINTF(cleanup, PATH_KSM "run", "1");

Let me format a new patch for this.

Regards,
Li WANG