Re: [PATCH 0/6] Overhaul memalloc_no*

Matthew Wilcox
2020-06-25T20:35:05Z

On Thu, Jun 25, 2020 at 11:48:32AM -0700, Darrick J. Wong wrote:
> On Thu, Jun 25, 2020 at 12:31:16PM +0100, Matthew Wilcox (Oracle) wrote:
> > I want a memalloc_nowait like we have memalloc_noio and memalloc_nofs
> > for an upcoming patch series, and Jens also wants it for non-blocking
> > io_uring. It turns out we already have dm-bufio which could benefit
> > from memalloc_nowait, so it may as well go into the tree now.
> >
> > The biggest problem is that we're basically out of PF_ flags, so we need
> > to find somewhere else to store the PF_MEMALLOC_NOWAIT flag. It turns
> > out the PF_ flags are really supposed to be used for flags which are
> > accessed from other tasks, and the MEMALLOC flags are only going to
> > be used by this task. So shuffling everything around frees up some PF
> > flags and generally makes the world a better place.
>
> So, uh, how does this intersect with the patch "xfs: reintroduce
> PF_FSTRANS for transaction reservation recursion protection" that
> re-adds PF_TRANS because uh I guess we lost some subtlety or another at
> some point?

I don't know. I read that thread, but I couldn't follow the argument.