On Sat, 2020-12-19 at 11:46 +0100, Vitaly Wool wrote:
> On Sat, 19 Dec 2020, 11:27 Mike Galbraith, <efa...@gmx.de> wrote:
>
> > The kernel that generated that splat was NOT an RT kernel, it was plain
> > master.today with a PREEMPT config.
>
>
> I see, thanks. I don't think it makes things better for zsmalloc
> though. From what I can see, the offending code is this:
>
> > /* From now on, migration cannot move the object */
> > pin_tag(handle);
>
> Bit spinlock is taken in pin_tag(). I find the comment above somewhat
> misleading, why is it necessary to take a spinlock to prevent
> migration? I would guess an atomic flag should normally be enough.
>
> zswap is not broken here, it is zsmalloc that needs to be fixed.
Cool, those damn bit spinlocks going away would be a case of happiness
for RT as well :)
-Mike
