Messages in this thread | | | Date | Wed, 17 Dec 2014 12:01:39 -0500 | From | Konrad Rzeszutek Wilk <> | Subject | Re: frequent lockups in 3.18rc4 |
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On Tue, Dec 16, 2014 at 04:41:16PM -0800, Andy Lutomirski wrote: > On Tue, Dec 16, 2014 at 4:00 PM, Linus Torvalds > <torvalds@linux-foundation.org> wrote: > > On Tue, Dec 16, 2014 at 3:02 PM, Peter Zijlstra <peterz@infradead.org> wrote: > >> > >> OK, should we just stick it in the x86 tree and see if anything > >> explodes? ;-) > > > > Gaah, I got confused about the patches. > > > > And something did explode, it showed some Xen nasties. Xen has that > > odd "we don't share PMD entries between MM's" thing going on, which > > means that the vmalloc fault thing does actually have to occasionally > > walk two levels rather than just copy the top level. I'm still not > > sure why Xen doesn't share PMD's, since threads that shame the MM > > clearly can share PMD's within Xen, but I gave up on it. > > Sounds like it's time to ask Konrad, the source of all Xen understanding :)
Awesome :-) > > Linus, do you have a pointer to whatever version of the patch you tried?
The patch was this:
a) http://article.gmane.org/gmane.linux.kernel/1835331
Then Jurgen had a patch: https://lkml.kernel.org/g/CA+55aFxSRujj=cM1NkXYvxmo=Y1hb1e3tgLhdh1JDphzV6WKRw@mail.gmail.com which was one fix for one bug that ended up being fixed in QEMU - so it can be ignored.
But my understanding of that thread was that it said patch 'a)' did not fix Dave's issues - and the conversation went off on NMI watchdog?
I will look up the giant thread to make sense.
> > --Andy > > > > > That said, making x86-64 use "read_cr3()" instead of > > "current->active_mm" would at least make things a bit safer wrt NMI's > > during the task switch, of course. So *some* 32/64-bit consolidation > > should be done, but my patch went a bit too far for Xen. > > > > Linus > > > > -- > Andy Lutomirski > AMA Capital Management, LLC
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