From: Michal Hocko <mhocko@kernel.org>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: linux-mm@kvack.org, wei.w.wang@intel.com, willy@infradead.org,
mst@redhat.com
Subject: Re: Is GFP_HIGHUSER[_MOVABLE] | __GFP_NOMEMALLOC) & ~__GFP_DIRECT_RECLAIM supported?
Date: Tue, 2 Jan 2018 10:14:57 +0100 [thread overview]
Message-ID: <20180102091457.GA25397@dhcp22.suse.cz> (raw)
In-Reply-To: <201801021108.BCC17635.FQtOHMOLJSVFFO@I-love.SAKURA.ne.jp>
On Tue 02-01-18 11:08:47, Tetsuo Handa wrote:
> virtio-balloon wants to try allocation only when that allocation does not cause
> OOM situation. Since there is no gfp flag which succeeds allocations only if
> there is plenty of free memory (i.e. higher watermark than other requests),
> virtio-balloon needs to watch for OOM notifier and release just allocated memory
> when OOM notifier is invoked.
I do not understand the last part mentioning OOM notifier.
> Currently virtio-balloon is using
>
> GFP_HIGHUSER[_MOVABLE] | __GFP_NOMEMALLOC | __GFP_NORETRY
>
> for allocation, but is
>
> GFP_HIGHUSER[_MOVABLE] | __GFP_NOMEMALLOC) & ~__GFP_DIRECT_RECLAIM
>
> supported (from MM subsystem's point of view) ?
Semantically I do not see any reason why we shouldn't support
non-sleeping user allocation with an explicit nomemalloc flag. Btw. why
is __GFP_NOMEMALLOC needed at all?
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2018-01-02 9:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-02 2:08 Tetsuo Handa
2018-01-02 9:14 ` Michal Hocko [this message]
2018-01-02 9:56 ` Tetsuo Handa
2018-01-02 11:40 ` Michal Hocko
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