[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] BUG: using smp_processor_id() in preemptible [00000000] code: blkback.1.xvdb/9138 caller is decrease_reservation
On Wed, 11 Sep 2013, David Vrabel wrote: > On 10/09/13 19:13, Sander Eikelenboom wrote: > > Hi Wei, > > > > Just back from holiday i tried running a new xen-unstable and linux > > kernel (current Linus his tree + Konrad's last pull request merged on top). > > I saw a thread and patch about a bug_on in increase_reservation ... > > i'm seeing the splat below in dom0 when guests get started. > > Yes, the use of __per_cpu() in decrease_reservation is not safe. > > Stefano, what testing did you give "xen/balloon: set a mapping for > ballooned out pages" (cd9151e2). The number of critical problems it's > had suggests not a lot? > > I'm also becoming less happy with the inconsistency between the p2m > updates between the different (non-)auto_translated_physmap guest types. > > I think it (and all the attempts to fix it) should be reverted at this > stage and we should try again for 3.13 which some more through testing > and a more careful look at what updates to the p2m are needed. Issues like this one are due to different kernel configurations / usage patters. To reproduce this issue one needs a preemptible kernel and blkback. I use a non-preemptible kernel and QEMU as block backend. Granted, in this case I should have tested blkback and both preemptible and non-preemptible kernel configurations. But in general it is nearly impossible to test all the possible configurations beforehand, it is a classic case of combinatorial explosion. These are exactly the kind of things that an exposure to a wider range of users/developers help identify and fix. So I think that we did the right thing here, by sending a pull request early in the release cycle, so that now we have many other RCs to fix all the issues that come up. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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