On Fri, Nov 30, 2012 at 07:14:59PM +0100, Michal Hocko wrote:
> On Fri 30-11-12 10:00:15, Wu Fengguang wrote:
> > On Thu, Nov 29, 2012 at 04:46:16PM -0800, Andrew Morton wrote:
> > > On Fri, 30 Nov 2012 08:28:48 +0800
> > > Fengguang Wu <fengguang.wu@xxxxxxxxx> wrote:
> > >
> > > > Hi Rafael,
> > > >
> > > > [Julia and me think that this coccinelle warning is worth reporting.]
> > > >
> > > > tree: git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git since-3.6
> > > > head: 422a0f651b5cefa1b6b3ede2e1c9e540a24a6e01
> > > > commit: 5f1da4063294480b3fabcee554f976565dec54b5 [341/499] virtio_balloon: introduce migration primitives to balloon pages
> > > >
> > > > + drivers/virtio/virtio_balloon.c:157:2-8: preceding lock on line 136
> > > >
> > > > vim +157 drivers/virtio/virtio_balloon.c
> > > >
> > > > 6b35e407 Rusty Russell 2008-02-04 130 {
> > > > 5f1da406 Rafael Aquini 2012-11-09 131 struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;
> > > > 5f1da406 Rafael Aquini 2012-11-09 132
> > > > 6b35e407 Rusty Russell 2008-02-04 133 /* We can only do one array worth at a time. */
> > > > 6b35e407 Rusty Russell 2008-02-04 134 num = min(num, ARRAY_SIZE(vb->pfns));
> > > > 6b35e407 Rusty Russell 2008-02-04 135
> > > > 5f1da406 Rafael Aquini 2012-11-09 @136 mutex_lock(&vb->balloon_lock);
> > > > 3ccc9372 Michael S. Tsirkin 2012-04-12 137 for (vb->num_pfns = 0; vb->num_pfns < num;
> > > > 3ccc9372 Michael S. Tsirkin 2012-04-12 138 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
> > > > 5f1da406 Rafael Aquini 2012-11-09 139 struct page *page = balloon_page_enqueue(vb_dev_info);
> > > > 5f1da406 Rafael Aquini 2012-11-09 140
> > > > 6b35e407 Rusty Russell 2008-02-04 141 if (!page) {
> > > > 6b35e407 Rusty Russell 2008-02-04 142 if (printk_ratelimit())
> > > > 6b35e407 Rusty Russell 2008-02-04 143 dev_printk(KERN_INFO, &vb->vdev->dev,
> > > > 6b35e407 Rusty Russell 2008-02-04 144 "Out of puff! Can't get %zu pages\n",
> > > > 5f1da406 Rafael Aquini 2012-11-09 145 VIRTIO_BALLOON_PAGES_PER_PAGE);
> > > > 6b35e407 Rusty Russell 2008-02-04 146 /* Sleep for at least 1/5 of a second before retry. */
> > > > 6b35e407 Rusty Russell 2008-02-04 147 msleep(200);
> > > > 6b35e407 Rusty Russell 2008-02-04 148 break;
> > > > 6b35e407 Rusty Russell 2008-02-04 149 }
> > > > 3ccc9372 Michael S. Tsirkin 2012-04-12 150 set_page_pfns(vb->pfns + vb->num_pfns, page);
> > > > 3ccc9372 Michael S. Tsirkin 2012-04-12 151 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
> > > > 6b35e407 Rusty Russell 2008-02-04 152 totalram_pages--;
> > > > 6b35e407 Rusty Russell 2008-02-04 153 }
> > > > 6b35e407 Rusty Russell 2008-02-04 154
> > > > 6b35e407 Rusty Russell 2008-02-04 155 /* Didn't get any? Oh well. */
> > > > 6b35e407 Rusty Russell 2008-02-04 156 if (vb->num_pfns == 0)
> > > > 6b35e407 Rusty Russell 2008-02-04 @157 return;
> > > > 6b35e407 Rusty Russell 2008-02-04 158
> > > > 6b35e407 Rusty Russell 2008-02-04 159 tell_host(vb, vb->inflate_vq);
> > > > 5f1da406 Rafael Aquini 2012-11-09 160 mutex_unlock(&vb->balloon_lock);
> > >
> > > This bug was fixed by
> > >
> > > virtio_balloon-introduce-migration-primitives-to-balloon-pages.patch
> > > this one -> virtio_balloon-introduce-migration-primitives-to-balloon-pages-fix.patch
> > > virtio_balloon-introduce-migration-primitives-to-balloon-pages-fix-fix.patch
> > > virtio_balloon-introduce-migration-primitives-to-balloon-pages-fix-fix-fix.patch
> >
> > Michal: your since-3.6 branch somehow missed that followup fix...
>
> Hmm strange, I can see all of them in my tree.
> 72d9876194be9e6f0600ca796b6689a77fce28b7
> f920c4f67b892a6b41054c5441ab0d481489c6c9
> 63db42f4243be26efffc32806990349235619bad
Oops.. the fixes are reverted by a later commit 4f2ac849
- /* Did we get any? */
- if (vb->num_pfns != 0)
- tell_host(vb, vb->inflate_vq);
- mutex_unlock(&vb->balloon_lock);
+ /* Didn't get any? Oh well. */
(*) + if (vb->num_pfns == 0)
(*) + return;
+
+ tell_host(vb, vb->inflate_vq);
(*) then we got the coccinelle warning again in the HEAD.
Thanks,
Fengguang
> merged in mmotm-2012-11-14-17-40
>
> and my mis-merge follow-up
> 83bb61967444e22100f7c6e2a5f79ffa85b9e981
>
> merged in mmotm-2012-11-26-17-32
> All of them should be
>
> --
> Michal Hocko
> SUSE Labs
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