Messages in this thread | | | Subject | Re: [PATCH] KVM: arm/arm64: add WARN_ON if size is not PAGE_SIZE aligned in unmap_stage2_range | From | Suzuki K Poulose <> | Date | Thu, 17 May 2018 09:17:44 +0100 |
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Hi Jia,
On 17/05/18 07:11, Jia He wrote: > I ever met a panic under memory pressure tests(start 20 guests and run > memhog in the host).
Please avoid using "I" in the commit description and preferably stick to an objective description.
> > The root cause might be what I fixed at [1]. But from arm kvm points of > view, it would be better we caught the exception earlier and clearer. > > If the size is not PAGE_SIZE aligned, unmap_stage2_range might unmap the > wrong(more or less) page range. Hence it caused the "BUG: Bad page > state"
I don't see why we should ever panic with a "positive" size value. Anyways, the unmap requests must be in units of pages. So this check might be useful.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> > [1] https://lkml.org/lkml/2018/5/3/1042 > > Signed-off-by: jia.he@hxt-semitech.com > --- > virt/kvm/arm/mmu.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c > index 7f6a944..8dac311 100644 > --- a/virt/kvm/arm/mmu.c > +++ b/virt/kvm/arm/mmu.c > @@ -297,6 +297,8 @@ static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size) > phys_addr_t next; > > assert_spin_locked(&kvm->mmu_lock); > + WARN_ON(size & ~PAGE_MASK); > + > pgd = kvm->arch.pgd + stage2_pgd_index(addr); > do { > /* >
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