Re: [PATCH v6 18/24] mm: Try spin lock in speculative path
- Date: Fri, 12 Jan 2018 10:18:40 -0800
- From: Matthew Wilcox <willy@xxxxxxxxxxxxx>
- Subject: Re: [PATCH v6 18/24] mm: Try spin lock in speculative path
On Fri, Jan 12, 2018 at 06:26:02PM +0100, Laurent Dufour wrote:
> There is a deadlock when a CPU is doing a speculative page fault and
> another one is calling do_unmap().
> The deadlock occurred because the speculative path try to spinlock the
> pte while the interrupt are disabled. When the other CPU in the
> unmap's path has locked the pte then is waiting for all the CPU to
> invalidate the TLB. As the CPU doing the speculative fault have the
> interrupt disable it can't invalidate the TLB, and can't get the lock.
> Since we are in a speculative path, we can race with other mm action.
> So let assume that the lock may not get acquired and fail the
> speculative page fault.
It seems like you introduced this bug in the previous patch, and now
you're fixing it in this patch? Why not merge the two?