Messages in this thread | | | Subject | Re: [BUG] Deadlock due due to interactions of block, RCU, and cpu offline | From | Jeffrey Hugo <> | Date | Sun, 20 Aug 2017 13:31:01 -0600 |
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On 6/29/2017 6:18 PM, Paul E. McKenney wrote: > On Thu, Jun 29, 2017 at 10:29:12AM -0600, Jeffrey Hugo wrote: >> On 6/27/2017 6:11 PM, Paul E. McKenney wrote: >>> On Tue, Jun 27, 2017 at 04:32:09PM -0600, Jeffrey Hugo wrote: >>>> On 6/22/2017 9:34 PM, Paul E. McKenney wrote: >>>>> On Wed, Jun 21, 2017 at 09:18:53AM -0700, Paul E. McKenney wrote: >>>>>> No worries, and I am very much looking forward to seeing the results of >>>>>> your testing. >>>>> >>>>> And please see below for an updated patch based on LKML review and >>>>> more intensive testing. >>>>> >>>> >>>> I spent some time on this today. It didn't go as I expected. I >>>> validated the issue is reproducible as before on 4.11 and 4.12 rcs 1 >>>> through 4. However, the version of stress-ng that I was using ran >>>> into constant errors starting with rc5, making it nearly impossible >>>> to make progress toward reproduction. Upgrading stress-ng to tip >>>> fixes the issue, however, I've still been unable to repro the issue. >>>> >>>> Its my unfounded suspicion that something went in between rc4 and >>>> rc5 which changed the timing, and didn't actually fix the issue. I >>>> will run the test overnight for 5 hours to try to repro. >>>> >>>> The patch you sent appears to be based on linux-next, and appears to >>>> have a number of dependencies which prevent it from cleanly applying >>>> on anything current that I'm able to repro on at this time. Do you >>>> want to provide a rebased version of the patch which applies to say >>>> 4.11? I could easily test that and report back. >>> >>> Here is a very lightly tested backport to v4.11. >>> >> >> Works for me. Always reproduced the lockup within 2 minutes on stock >> 4.11. With the change applied, I was able to test for 2 hours in >> the same conditions, and 4 hours with the full system and not >> encounter an issue. >> >> Feel free to add: >> Tested-by: Jeffrey Hugo <jhugo@codeaurora.org> > > Applied, thank you! > >> I'm going to go back to 4.12-rc5 and see if I can get either repro >> the issue, or identify what changed. Hopefully I can get to >> linux-next and double check the original version of the change as >> well. > > Looking forward to hearing what you find! > > Thanx, Paul >
According to git bisect, the following is what "changed"
commit 9d0eb4624601ac978b9e89be4aeadbd51ab2c830 Merge: 5faab9e 9bc1f09 Author: Linus Torvalds <torvalds@linux-foundation.org> Date: Sun Jun 11 11:07:25 2017 -0700
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM fixes from Paolo Bonzini: "Bug fixes (ARM, s390, x86)"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: KVM: async_pf: avoid async pf injection when in guest mode KVM: cpuid: Fix read/write out-of-bounds vulnerability in cpuid emulation arm: KVM: Allow unaligned accesses at HYP arm64: KVM: Allow unaligned accesses at EL2 arm64: KVM: Preserve RES1 bits in SCTLR_EL2 KVM: arm/arm64: Handle possible NULL stage2 pud when ageing pages KVM: nVMX: Fix exception injection kvm: async_pf: fix rcu_irq_enter() with irqs enabled KVM: arm/arm64: vgic-v3: Fix nr_pre_bits bitfield extraction KVM: s390: fix ais handling vs cpu model KVM: arm/arm64: Fix isues with GICv2 on GICv3 migration
Nothing really stands out to me which would "fix" the issue.
-- Jeffrey Hugo Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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