Re: [PATCH v2] kernel/exit: do panic earlier to get coredump if global init task exit

[Peter Zijlstra]

On Tue, Dec 17, 2019 at 04:23:33PM +0100, Oleg Nesterov wrote:
> On 12/17, chenqiwu wrote:
> >
> > But in fact, I think atomic_read()
> > can avoid the racy even if both threads exit in parallel, since it is
> > an atomic operation forever.
> 
> Hmm, not sure I understand. atomic_read() is just READ_ONCE(), it can't be
> re-ordered but that is all.

That, atomic_read() is just a read. It doesn't modify the variable,
therefore there isn't anything 'atomic' even remotely possible.