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From: Paolo Bonzini <pbonzini@redhat.com>
To: Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Marc Zyngier <maz@kernel.org>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Paul Mackerras <paulus@ozlabs.org>
Subject: Re: [PATCH 0/2] KVM: arm64: Fix sleeping while atomic BUG() on OOM
Date: Tue, 18 Aug 2020 08:31:08 +0200	[thread overview]
Message-ID: <ff1d4de2-f3f8-eafa-6ba5-3e5bb715ae05@redhat.com> (raw)
In-Reply-To: <20200811102725.7121-1-will@kernel.org>

On 11/08/20 12:27, Will Deacon wrote:
> Hi all,
> 
> While stress-testing my arm64 stage-2 page-table rewrite [1], I ran into
> a sleeping while atomic BUG() during OOM that I can reproduce with
> mainline.
> 
> The problem is that the arm64 page-table code periodically calls
> cond_resched_lock() when unmapping the stage-2 page-tables, but in the
> case of OOM, this occurs in atomic context.
> 
> These couple of patches (based on 5.8) propagate the flags from the MMU
> notifier range structure, which in turn indicate whether or not blocking
> is permitted.
> 
> Cheers,
> 
> Will
> 
> [1] https://android-kvm.googlesource.com/linux/+/refs/heads/topic/pgtable
> 
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Paul Mackerras <paulus@ozlabs.org>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> --->8
> 
> Will Deacon (2):
>   KVM: Pass MMU notifier range flags to kvm_unmap_hva_range()
>   KVM: arm64: Only reschedule if MMU_NOTIFIER_RANGE_BLOCKABLE is not set
> 
>  arch/arm64/include/asm/kvm_host.h   |  2 +-
>  arch/arm64/kvm/mmu.c                | 19 ++++++++++++++-----
>  arch/mips/include/asm/kvm_host.h    |  2 +-
>  arch/mips/kvm/mmu.c                 |  3 ++-
>  arch/powerpc/include/asm/kvm_host.h |  3 ++-
>  arch/powerpc/kvm/book3s.c           |  3 ++-
>  arch/powerpc/kvm/e500_mmu_host.c    |  3 ++-
>  arch/x86/include/asm/kvm_host.h     |  3 ++-
>  arch/x86/kvm/mmu/mmu.c              |  3 ++-
>  virt/kvm/kvm_main.c                 |  3 ++-
>  10 files changed, 30 insertions(+), 14 deletions(-)
> 

These would be okay for 5.9 too, so I plan to queue them myself before
we fork for 5.10.

Paolo

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  parent reply	other threads:[~2020-08-18  6:31 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-11 10:27 [PATCH 0/2] KVM: arm64: Fix sleeping while atomic BUG() on OOM Will Deacon
2020-08-11 10:27 ` [PATCH 1/2] KVM: Pass MMU notifier range flags to kvm_unmap_hva_range() Will Deacon
2020-08-19 23:57   ` Sasha Levin
2020-08-26 13:54   ` Sasha Levin
2020-08-11 10:27 ` [PATCH 2/2] KVM: arm64: Only reschedule if MMU_NOTIFIER_RANGE_BLOCKABLE is not set Will Deacon
2020-08-11 10:52   ` Suzuki K Poulose
2020-08-18  6:31 ` Paolo Bonzini [this message]
2020-08-18 10:16   ` [PATCH 0/2] KVM: arm64: Fix sleeping while atomic BUG() on OOM Will Deacon
2020-08-18 10:30     ` Marc Zyngier
2020-08-20  7:26     ` Paolo Bonzini
2020-08-18 10:34 ` Marc Zyngier

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