On 07/23/2014 01:36 PM, Gavin Shan wrote:
> On Wed, Jul 23, 2014 at 01:05:49PM +1000, Alexey Kardashevskiy wrote:
>> Signed-off-by: Alexey Kardashevskiy <[email protected]>
>> ---
>> arch/powerpc/kvm/book3s_64_vio.c | 35 ++++++++++++++++++++++++++++++++++-
>> 1 file changed, 34 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kvm/book3s_64_vio.c
>> b/arch/powerpc/kvm/book3s_64_vio.c
>> index 516f2ee..48b7ed4 100644
>> --- a/arch/powerpc/kvm/book3s_64_vio.c
>> +++ b/arch/powerpc/kvm/book3s_64_vio.c
>> @@ -45,18 +45,48 @@ static long kvmppc_stt_npages(unsigned long window_size)
>> * sizeof(u64), PAGE_SIZE) / PAGE_SIZE;
>> }
>>
>> +/*
>> + * Checks ulimit in order not to let the user space to pin all
>> + * available memory for TCE tables.
>> + */
>> +static long kvmppc_account_memlimit(long npages)
>> +{
>> + unsigned long ret = 0, locked, lock_limit;
>> +
>> + if (!current->mm)
>> + return -ESRCH; /* process exited */
>> +
>> + down_write(¤t->mm->mmap_sem);
>> + locked = current->mm->locked_vm + npages;
>> + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
>> + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
>
> I took a look on mm/mlock.c::mlock() where the mlock operation
> is allowd while we have one of following conditions (not &&) :-)
>
> /* check against resource limits */
> if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
> error = do_mlock(start, len, 1);
So? if() that you posted does lock, the if() I posted does completely
opposite operation. It is not just || vs. &&, other conditions changed too.
drivers/vfio/vfio_iommu_spapr_tce.c has the same chunk which I copied here,
for example.
>
> Thanks,
> Gavin
>
>> + pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n",
>> + rlimit(RLIMIT_MEMLOCK));
>> + ret = -ENOMEM;
>> + } else {
>> + current->mm->locked_vm += npages;
>> + }
>> + up_write(¤t->mm->mmap_sem);
>> +
>> + return ret;
>> +}
>> +
>> static void release_spapr_tce_table(struct kvmppc_spapr_tce_table *stt)
>> {
>> struct kvm *kvm = stt->kvm;
>> int i;
>> + long npages = kvmppc_stt_npages(stt->window_size);
>>
>> mutex_lock(&kvm->lock);
>> list_del(&stt->list);
>> - for (i = 0; i < kvmppc_stt_npages(stt->window_size); i++)
>> + for (i = 0; i < npages; i++)
>> __free_page(stt->pages[i]);
>> +
>> kfree(stt);
>> mutex_unlock(&kvm->lock);
>>
>> + kvmppc_account_memlimit(-(npages + 1));
>> +
>> kvm_put_kvm(kvm);
>> }
>>
>> @@ -112,6 +142,9 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>> }
>>
>> npages = kvmppc_stt_npages(args->window_size);
>> + ret = kvmppc_account_memlimit(npages + 1);
>> + if (ret)
>> + goto fail;
>>
>> stt = kzalloc(sizeof(*stt) + npages * sizeof(struct page *),
>> GFP_KERNEL);
>> --
>> 2.0.0
>>
>
--
Alexey
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