[LTP] [PATCH] tst_pollute_memory(): Set minimal safety margin to 64MB

From: Cyril Hrubis <chrubis@suse.cz>
To: ltp@lists.linux.it
Subject: [LTP] [PATCH] tst_pollute_memory(): Set minimal safety margin to 64MB
Date: Wed, 20 Jan 2021 15:54:11 +0100	[thread overview]
Message-ID: <YAhEEzWShFLlHrk1@yuki.lan> (raw)
In-Reply-To: <CA+G9fYv_6tiMrF38jLPYK=C6D+LNBndun1XuGQJiOK60LhYRyA@mail.gmail.com>

Hi!
> > > -     safety = 4096 * SAFE_SYSCONF(_SC_PAGESIZE) / info.mem_unit;
> > > +     safety = MAX(4096 * SAFE_SYSCONF(_SC_PAGESIZE), 64 * 1024 * 1024);
> > > +     safety /= info.mem_unit;
> >
> > I guess that this is safe enough for the release, since it will only
> > increase the safety margin.
> >
> > Naresh can you please test this patch ASAP?
> 
> I have applied your patch and rebuilt completely and retested
> ioctl_sg01 test case in a loop on three different devices.
> 
> 1 PASS out of 20 runs with overcommit_memory 0 on x86_64.
> 1 PASS out of 20 runs with overcommit_memory 1 on x86_64.
> 
> Which means 19 times the test case triggered oom-killer and the test was broken.

So it looks like 64MB is not enough in your case.

Does it work with 128MB or 256MB?

i.e.:

safety = MAX(4096 * SAFE_SYSCONF(_SC_PAGESIZE), 128 * 1024 * 1024);
safety = MAX(4096 * SAFE_SYSCONF(_SC_PAGESIZE), 256 * 1024 * 1024);

-- 
Cyril Hrubis
chrubis@suse.cz