On Mon 06-03-17 13:22:14, Andrew Morton wrote:
> On Mon, 6 Mar 2017 14:14:05 +0100 Michal Hocko <mhocko@xxxxxxxxxx> wrote:
[...]
> > --- a/include/linux/gfp.h
> > +++ b/include/linux/gfp.h
> > @@ -210,8 +210,16 @@ struct vm_area_struct;
> > *
> > * GFP_NOIO will use direct reclaim to discard clean pages or slab pages
> > * that do not require the starting of any physical IO.
> > + * Please try to avoid using this flag directly and instead use
> > + * memalloc_noio_{save,restore} to mark the whole scope which cannot
> > + * perform any IO with a short explanation why. All allocation requests
> > + * will inherit GFP_NOIO implicitly.
> > *
> > * GFP_NOFS will use direct reclaim but will not use any filesystem interfaces.
> > + * 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.
>
> I wonder if these are worth a checkpatch rule.
I am not really sure, to be honest. This may easilly end up people
replacing
do_alloc(GFP_NOFS)
with
memalloc_nofs_save()
do_alloc(GFP_KERNEL)
memalloc_nofs_restore()
which doesn't make any sense of course. From my experience, people tend
to do stupid things just to silent checkpatch warnings very often.
Moreover I believe we need to do the transition to the new api first
before we can push back on the explicit GFP_NOFS usage. Maybe then we
can think about the a checkpatch warning.
--
Michal Hocko
SUSE Labs
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