From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 1/2] memcg: flatten task_struct->memcg_oom
Date: Wed, 25 Nov 2015 18:44:49 +0100
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To: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>, Sasha Levin <sasha.levin@oracle.com>, Andrew Morton <akpm@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, mhocko@kernel.org, cgroups@vger.kernel.org, "linux-mm@kvack.org" <linux-mm@kvack.org>, vdavydov@parallels.com, kernel-team@fb.com, Dmitry Vyukov <dvyukov@google.com>

On Wed, Nov 25, 2015 at 06:31:41PM +0300, Andrey Ryabinin wrote:
> > +       /* scheduler bits, serialized by scheduler locks */
> >         unsigned sched_reset_on_fork:1;
> >         unsigned sched_contributes_to_load:1;
> >         unsigned sched_migrated:1;
> > +       unsigned __padding_sched:29;
> 
> AFAIK the order of bit fields is implementation defined, so GCC could
> sort all these bits as it wants.

We're relying on it doing DTRT in other places, so I'm fairly confident
this'll work, otoh

> You could use unnamed zero-widht bit-field to force padding:
> 
>          unsigned :0; //force aligment to the next boundary.

That's a nice trick I was not aware of, thanks!

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