On Thu, 2018-12-20 at 10:52 -0500, Bruce Fields wrote:
> On Thu, Dec 20, 2018 at 10:47:25AM -0500, Chuck Lever wrote:
> >
> > > On Dec 20, 2018, at 10:42 AM, J. Bruce Fields <
> > > bfields@xxxxxxxxxxxx> wrote:
> > >
> > > From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
> > >
> > > It's OK to sleep here, we just don't want to recurse into the
> > > filesystem
> > > as this writeout could be waiting on this.
> >
> > "as a writeout"
>
> Oops, thanks.
>
> > > Future work: the documentation for GFP_NOFS says "Please try to
> > > avoid
> > > using this flag directly and instead use
> > > memalloc_nofs_{save,restore} to
> > > mark the whole scope which cannot/shouldn't recurse into the FS
> > > layer
> > > with a short explanation why. All allocation requests will
> > > inherit
> > > GFP_NOFS implicitly."
> > >
> > > But I'm not sure where to do this. Should the workqueue be
> > > arranging
> > > that for us in the case of workqueues created with
> > > WQ_MEM_RECLAIM?
> >
> > There seem to be plenty of uses of GFP_NOFS in NFS and sunrpc.
> > That sounds like a big project.
>
> Yeah, just noting it for future reference.
>
I'd suggest that we can probably just call memalloc_nofs_save() in
rpc_execute(), and otherwise in those workqueue callback functions that
are executed directly by rpciod and xprtiod. That doesn't make for too
many callsites.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
