On Tue, Feb 14, 2017 at 11:42:21AM +0530, Vipin K Parashar wrote:
> kvm_ppc_mmu_book3s_32/64 xlat() log "KVM can't copy data" error
> upon failing to copy user data to kernel space. This floods kernel
> log once such fails occur in short time period. Ratelimit this
> error to avoid flooding kernel logs upon copy data failures.
>
> Signed-off-by: Vipin K Parashar <vipin@xxxxxxxxxxxxxxxxxx>
> ---
> arch/powerpc/kvm/book3s_32_mmu.c | 3 ++-
> arch/powerpc/kvm/book3s_64_mmu.c | 3 ++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_32_mmu.c b/arch/powerpc/kvm/book3s_32_mmu.c
> index a2eb6d3..ca8f960 100644
> --- a/arch/powerpc/kvm/book3s_32_mmu.c
> +++ b/arch/powerpc/kvm/book3s_32_mmu.c
> @@ -224,7 +224,8 @@ static int kvmppc_mmu_book3s_32_xlate_pte(struct kvm_vcpu *vcpu, gva_t eaddr,
> ptem = kvmppc_mmu_book3s_32_get_ptem(sre, eaddr, primary);
>
> if(copy_from_user(pteg, (void __user *)ptegp, sizeof(pteg))) {
> - printk(KERN_ERR "KVM: Can't copy data from 0x%lx!\n", ptegp);
> + if (printk_ratelimit())
> + printk(KERN_ERR "KVM: Can't copy data from 0x%lx!\n", ptegp);
I found this in include/linux/printk.h:
/*
* Please don't use printk_ratelimit(), because it shares ratelimiting state
* with all other unrelated printk_ratelimit() callsites. Instead use
* printk_ratelimited() or plain old __ratelimit().
*/
It does seem that using printk_ratelimited(KERN_ERR ...) or the
equivalent pr_err_ratelimited(...) would be a better option.
Paul.
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