From: "Michael S. Tsirkin" <mst@redhat.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Konstantin Khlebnikov <koct9i@gmail.com>,
Rafael Aquini <aquini@redhat.com>,
stable@vger.kernel.org
Subject: Re: [PATCH 2/2] virtio_balloon: fix race between migration and ballooning
Date: Sun, 10 Jan 2016 23:40:17 +0200 [thread overview]
Message-ID: <20160110233310-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <20160104002747.GA31090@blaptop.local>
On Mon, Jan 04, 2016 at 09:27:47AM +0900, Minchan Kim wrote:
> > I think this will cause deadlocks.
> >
> > pages_lock now nests within page lock, balloon_page_putback
> > nests them in the reverse order.
>
> In balloon_page_dequeu, we used trylock so I don't think it's
> deadlock.
I went over this again and I don't see the issue anymore.
I think I was mistaken, so I dropped my patch and picked
up yours. Sorry about the noise.
> >
> > Also, there's another issue there I think: after isolation page could
> > also get freed before we try to lock it.
>
> If a page was isolated, the page shouldn't stay b_dev_info->pages
> list so balloon_page_dequeue cannot see the page.
> Am I missing something?
I mean without locks, as it is now. With either your or my patch in
place, it's fine.
--
MST
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WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Konstantin Khlebnikov <koct9i@gmail.com>,
Rafael Aquini <aquini@redhat.com>,
stable@vger.kernel.org
Subject: Re: [PATCH 2/2] virtio_balloon: fix race between migration and ballooning
Date: Sun, 10 Jan 2016 23:40:17 +0200 [thread overview]
Message-ID: <20160110233310-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <20160104002747.GA31090@blaptop.local>
On Mon, Jan 04, 2016 at 09:27:47AM +0900, Minchan Kim wrote:
> > I think this will cause deadlocks.
> >
> > pages_lock now nests within page lock, balloon_page_putback
> > nests them in the reverse order.
>
> In balloon_page_dequeu, we used trylock so I don't think it's
> deadlock.
I went over this again and I don't see the issue anymore.
I think I was mistaken, so I dropped my patch and picked
up yours. Sorry about the noise.
> >
> > Also, there's another issue there I think: after isolation page could
> > also get freed before we try to lock it.
>
> If a page was isolated, the page shouldn't stay b_dev_info->pages
> list so balloon_page_dequeue cannot see the page.
> Am I missing something?
I mean without locks, as it is now. With either your or my patch in
place, it's fine.
--
MST
next prev parent reply other threads:[~2016-01-10 21:40 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-27 23:35 [PATCH 1/2] virtio_balloon: fix race by fill and leak Minchan Kim
2015-12-27 23:35 ` Minchan Kim
2015-12-27 23:35 ` Minchan Kim
2015-12-27 23:35 ` [PATCH 2/2] virtio_balloon: fix race between migration and ballooning Minchan Kim
2015-12-27 23:35 ` Minchan Kim
2015-12-27 23:35 ` Minchan Kim
2015-12-27 23:35 ` Minchan Kim
2015-12-27 23:36 ` Rafael Aquini
2015-12-27 23:36 ` Rafael Aquini
2015-12-27 23:36 ` Rafael Aquini
2016-01-01 9:36 ` Michael S. Tsirkin
2016-01-01 9:36 ` Michael S. Tsirkin
2016-01-04 0:27 ` Minchan Kim
2016-01-04 0:27 ` Minchan Kim
2016-01-04 0:27 ` Minchan Kim
2016-01-10 21:40 ` Michael S. Tsirkin
2016-01-10 21:40 ` Michael S. Tsirkin [this message]
2016-01-10 21:40 ` Michael S. Tsirkin
2016-01-10 23:54 ` Minchan Kim
2016-01-10 23:54 ` Minchan Kim
2016-01-10 23:54 ` Minchan Kim
2016-01-08 19:56 ` Rafael Aquini
2016-01-08 19:56 ` Rafael Aquini
2016-01-08 23:43 ` Minchan Kim
2016-01-08 23:43 ` Minchan Kim
2016-01-08 23:43 ` Minchan Kim
2016-01-09 21:43 ` Michael S. Tsirkin
2016-01-09 21:43 ` Michael S. Tsirkin
2016-01-09 21:43 ` Michael S. Tsirkin
2016-01-09 23:03 ` Rafael Aquini
2016-01-09 23:03 ` Rafael Aquini
2016-01-09 23:03 ` Rafael Aquini
2016-01-08 19:56 ` Rafael Aquini
2016-01-01 9:36 ` Michael S. Tsirkin
2015-12-27 23:36 ` [PATCH 1/2] virtio_balloon: fix race by fill and leak Rafael Aquini
2015-12-27 23:36 ` Rafael Aquini
2015-12-27 23:36 ` Rafael Aquini
2016-01-01 8:26 ` Michael S. Tsirkin
2016-01-01 8:26 ` Michael S. Tsirkin
2016-01-01 8:26 ` Michael S. Tsirkin
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