Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap address space

From	Chris Wilson <chris@chris-wilson.co.uk>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap address space
Date	2016-03-17 14:40 +0100
Message-ID	<rdGjD-80w-3@gated-at.bofh.it> (permalink)
References	<rdEKS-6X2-27@gated-at.bofh.it> <rdFnA-7qC-25@gated-at.bofh.it> <rdG9Z-7Xh-29@gated-at.bofh.it> <rdG9Z-7Xh-27@gated-at.bofh.it>
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On Thu, Mar 17, 2016 at 02:21:40PM +0100, Roman Peniaev wrote:
> On Thu, Mar 17, 2016 at 1:57 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > On Thu, Mar 17, 2016 at 01:37:06PM +0100, Roman Peniaev wrote:
> >> > +       freed = 0;
> >> > +       blocking_notifier_call_chain(&vmap_notify_list, 0, &freed);
> >>
> >> It seems to me that alloc_vmap_area() was designed not to sleep,
> >> at least on GFP_NOWAIT path (__GFP_DIRECT_RECLAIM is not set).
> >>
> >> But blocking_notifier_call_chain() might sleep.
> >
> > Indeed, I had not anticipated anybody using GFP_ATOMIC or equivalently
> > restrictive gfp_t for vmap and yes there are such callers.
> >
> > Would guarding the notifier with gfp & __GFP_DIRECT_RECLAIM and
> > !(gfp & __GFP_NORETRY) == be sufficient? Is that enough for GFP_NOFS?
> 
> I would use gfpflags_allow_blocking() for that purpose.

Thanks,
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Thread

[PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap address space Chris Wilson <chris@chris-wilson.co.uk> - 2016-03-17 13:00 +0100
  [PATCH 2/2] drm/i915/shrinker: Hook up vmap allocation failure notifier Chris Wilson <chris@chris-wilson.co.uk> - 2016-03-17 13:10 +0100
  Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap  address space Roman Peniaev <r.peniaev@gmail.com> - 2016-03-17 13:40 +0100
    Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap  address space Roman Peniaev <r.peniaev@gmail.com> - 2016-03-17 14:30 +0100
      Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap  address space Chris Wilson <chris@chris-wilson.co.uk> - 2016-03-17 14:40 +0100
    Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap  address space Chris Wilson <chris@chris-wilson.co.uk> - 2016-03-17 14:30 +0100
  [PATCH v2] mm/vmap: Add a notifier for when we run out of vmap address space Chris Wilson <chris@chris-wilson.co.uk> - 2016-03-17 14:40 +0100
    Re: [PATCH v2] mm/vmap: Add a notifier for when we run out of vmap  address space Chris Wilson <chris@chris-wilson.co.uk> - 2016-03-17 14:50 +0100
      Re: [PATCH v2] mm/vmap: Add a notifier for when we run out of vmap  address space Andrew Morton <akpm@linux-foundation.org> - 2016-03-29 01:20 +0200
        [PATCH v3] mm/vmap: Add a notifier for when we run out of vmap address space Chris Wilson <chris@chris-wilson.co.uk> - 2016-03-29 10:20 +0200

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