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From: Roman Peniaev <r.peniaev@gmail.com>
To: Chris Wilson <chris@chris-wilson.co.uk>,
	Roman Peniaev <r.peniaev@gmail.com>,
	intel-gfx@lists.freedesktop.org,
	Andrew Morton <akpm@linux-foundation.org>,
	David Rientjes <rientjes@google.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	linux-mm@kvack.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap address space
Date: Thu, 17 Mar 2016 14:21:40 +0100	[thread overview]
Message-ID: <CACZ9PQWMr4bU3ao46MF6dab2fhTDwL7g59iR0AcpbSPm91qD4g@mail.gmail.com> (raw)
In-Reply-To: <20160317125736.GT14143@nuc-i3427.alporthouse.com>

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.

Roman

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  reply	other threads:[~2016-03-17 13:21 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-17 11:59 Chris Wilson
2016-03-17 11:59 ` [PATCH 2/2] drm/i915/shrinker: Hook up vmap allocation failure notifier Chris Wilson
2016-03-17 12:37 ` [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap address space Roman Peniaev
2016-03-17 12:57   ` Chris Wilson
2016-03-17 13:21     ` Roman Peniaev [this message]
2016-03-17 13:30       ` Chris Wilson
2016-03-17 13:34 ` [PATCH v2] " Chris Wilson
2016-03-17 13:41   ` Chris Wilson
2016-03-28 23:15     ` Andrew Morton
2016-03-29  8:16       ` [PATCH v3] " Chris Wilson

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