Re: kernel 3.0: BUG: soft lockup: find_get_pages+0x51/0x110

[Pawel Sikora]

On Friday 21 of October 2011 14:54:29 Nai Xia wrote:
> 2011/10/20 PaweÅ Sikora <pluto@xxxxxxxx>:
> > On Wednesday 19 of October 2011 21:42:15 Hugh Dickins wrote:
> >> On Wed, 19 Oct 2011, Linus Torvalds wrote:
> >> > On Wed, Oct 19, 2011 at 12:43 AM, Mel Gorman <mgorman@xxxxxxx> wrote:
> >> > >
> >> > > My vote is with the migration change. While there are occasionally
> >> > > patches to make migration go faster, I don't consider it a hot path.
> >> > > mremap may be used intensively by JVMs so I'd loathe to hurt it.
> >> >
> >> > Ok, everybody seems to like that more, and it removes code rather than
> >> > adds it, so I certainly prefer it too. Pawel, can you test that other
> >> > patch (to mm/migrate.c) that Hugh posted? Instead of the mremap vma
> >> > locking patch that you already verified for your setup?
> >> >
> >> > Hugh - that one didn't have a changelog/sign-off, so if you could
> >> > write that up, and Pawel's testing is successful, I can apply it...
> >> > Looks like we have acks from both Andrea and Mel.
> >>
> >> Yes, I'm glad to have that input from Andrea and Mel, thank you.
> >>
> >> Here we go.  I can't add a Tested-by since Pawel was reporting on the
> >> alternative patch, but perhaps you'll be able to add that in later.
> >>
> >> I may have read too much into Pawel's mail, but it sounded like he
> >> would have expected an eponymous find_get_pages() lockup by now,
> >> and was pleased that this patch appeared to have cured that.
> >>
> >> I've spent quite a while trying to explain find_get_pages() lockup by
> >> a missed migration entry, but I just don't see it: I don't expect this
> >> (or the alternative) patch to do anything to fix that problem.  I won't
> >> mind if it magically goes away, but I expect we'll need more info from
> >> the debug patch I sent Justin a couple of days ago.
> >
> > the latest patch (mm/migrate.c) applied on 3.0.4 also survives points
> > 1) and 2) described previously (https://lkml.org/lkml/2011/10/18/427),
> > so please apply it to the upstream/stable git tree.
> >
> > from the other side, both patches don't help for 3.0.4+vserver host soft-lock
> 
> Hi PaweÅ,
> 
> Did your "both" mean that you applied each patch and run the tests separately,

yes, i've tested Hugh's patches separately.

> Maybe there were more than one bugs dancing but having a same effect,
> not fixing all of them wouldn't help at all.

i suppose that vserver patch only exposes some tricky bug introduced in 2.6.38.

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