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

[Hugh Dickins <hughd@google.com>]

[-- Attachment #1: Type: text/plain, Size: 2883 bytes --]

I'm travelling at the moment, my brain is not in gear, the source is not in
front of me, and I'm not used to typing on my phone much!  Excuses, excuses

I flip between thinking you are right, and I'm a fool, and thinking you are
wrong, and I'm still a fool.

Please work it out with Linus, Andrea and Mel: I may not be able to reply
for a couple of days - thanks.

Hugh
On Oct 20, 2011 5:51 AM, "Nai Xia" <nai.xia@gmail.com> wrote:

> On Thursday 20 October 2011 03:42:15 Hugh Dickins wrote:
> > On Wed, 19 Oct 2011, Linus Torvalds wrote:
> > > On Wed, Oct 19, 2011 at 12:43 AM, Mel Gorman <mgorman@suse.de> 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.
>
> Hi Hugh,
>
> Will you please look into my explanation in my reply to Andrea in this
> thread
> and see if it's what you are seeking?
>
>
> Thanks,
>
> Nai Xia
>
>
> >
> > Ah, I'd better send the patch separately as
> > "[PATCH] mm: fix race between mremap and removing migration entry":
> > Pawel's "l" makes my old alpine setup choose quoted printable when
> > I reply to your mail.
> >
> > Hugh
> >
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@kvack.org.  For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Fight unfair telecom internet charges in Canada: sign
> http://stopthemeter.ca/
> > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> >
>

[-- Attachment #2: Type: text/html, Size: 3907 bytes --]