linux-kernel - Re: [PATCH v1 2/3] virtio-balloon: deflate up to oom

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Message-Id: <201710221311.FFI17148.VStOJQLHOFFMOF@I-love.SAKURA.ne.jp>
Date:   Sun, 22 Oct 2017 13:11:13 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     mst@...hat.com, wei.w.wang@...el.com
Cc:     mhocko@...nel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v1 2/3] virtio-balloon: deflate up to oom_pages on OOM

Michael S. Tsirkin wrote:
> On Fri, Oct 20, 2017 at 07:54:25PM +0800, Wei Wang wrote:
> > The current implementation only deflates 256 pages even when a user
> > specifies more than that via the oom_pages module param. This patch
> > enables the deflating of up to oom_pages pages if there are enough
> > inflated pages.
> 
> This seems reasonable. Does this by itself help?

At least

> > -	num_freed_pages = leak_balloon(vb, oom_pages);
> > +
> > +	/* Don't deflate more than the number of inflated pages */
> > +	while (npages && atomic64_read(&vb->num_pages))
> > +		npages -= leak_balloon(vb, npages);

don't we need to abort if leak_balloon() returned 0 for some reason?