Re: [PATCH 2/7] sched: Fix picking a task switching on other cpu (__ARCH_WANT_UNLOCKED_CTXSW)

From: Peter Zijlstra
Date: Sat Sep 20 2014 - 14:55:09 EST


On Sat, Sep 20, 2014 at 08:33:26PM +0200, Peter Zijlstra wrote:
> On Sat, Sep 20, 2014 at 08:51:22PM +0400, Kirill Tkhai wrote:
> > From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
> >
> > We may pick a task which is in context_switch() on other cpu at the moment.
> > Parallel using of a single stack by two processes is not a good idea.
>
> Please elaborate on who exactly that might happen. Its best to have
> comprehensive changelogs for issues that fix races.

FWIW IIRC we can remove UNLOCKED_CTXSW from IA64 and I forgot if I
audited MIPS, but I suspect we can (and should) remove it there too.

That would make this exception go away and clean up some of this ugly.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/