Messages in this thread | | | Subject | Re: [PATCH v3 2/2] vhost-vdpa: fix page pinning leakage in error path | From | Jason Wang <> | Date | Wed, 14 Oct 2020 19:41:17 +0800 |
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On 2020/10/14 下午2:52, Michael S. Tsirkin wrote: > On Tue, Oct 13, 2020 at 04:42:59PM -0700, si-wei liu wrote: >> On 10/9/2020 7:27 PM, Jason Wang wrote: >>> On 2020/10/3 下午1:02, Si-Wei Liu wrote: >>>> Pinned pages are not properly accounted particularly when >>>> mapping error occurs on IOTLB update. Clean up dangling >>>> pinned pages for the error path. As the inflight pinned >>>> pages, specifically for memory region that strides across >>>> multiple chunks, would need more than one free page for >>>> book keeping and accounting. For simplicity, pin pages >>>> for all memory in the IOVA range in one go rather than >>>> have multiple pin_user_pages calls to make up the entire >>>> region. This way it's easier to track and account the >>>> pages already mapped, particularly for clean-up in the >>>> error path. >>>> >>>> Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend") >>>> Signed-off-by: Si-Wei Liu<si-wei.liu@oracle.com> >>>> --- >>>> Changes in v3: >>>> - Factor out vhost_vdpa_map() change to a separate patch >>>> >>>> Changes in v2: >>>> - Fix incorrect target SHA1 referenced >>>> >>>> drivers/vhost/vdpa.c | 119 >>>> ++++++++++++++++++++++++++++++--------------------- >>>> 1 file changed, 71 insertions(+), 48 deletions(-) >>>> >>>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c >>>> index 0f27919..dad41dae 100644 >>>> --- a/drivers/vhost/vdpa.c >>>> +++ b/drivers/vhost/vdpa.c >>>> @@ -595,21 +595,19 @@ static int >>>> vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v, >>>> struct vhost_dev *dev = &v->vdev; >>>> struct vhost_iotlb *iotlb = dev->iotlb; >>>> struct page **page_list; >>>> - unsigned long list_size = PAGE_SIZE / sizeof(struct page *); >>>> + struct vm_area_struct **vmas; >>>> unsigned int gup_flags = FOLL_LONGTERM; >>>> - unsigned long npages, cur_base, map_pfn, last_pfn = 0; >>>> - unsigned long locked, lock_limit, pinned, i; >>>> + unsigned long map_pfn, last_pfn = 0; >>>> + unsigned long npages, lock_limit; >>>> + unsigned long i, nmap = 0; >>>> u64 iova = msg->iova; >>>> + long pinned; >>>> int ret = 0; >>>> if (vhost_iotlb_itree_first(iotlb, msg->iova, >>>> msg->iova + msg->size - 1)) >>>> return -EEXIST; >>>> - page_list = (struct page **) __get_free_page(GFP_KERNEL); >>>> - if (!page_list) >>>> - return -ENOMEM; >>>> - >>>> if (msg->perm & VHOST_ACCESS_WO) >>>> gup_flags |= FOLL_WRITE; >>>> @@ -617,61 +615,86 @@ static int >>>> vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v, >>>> if (!npages) >>>> return -EINVAL; >>>> + page_list = kvmalloc_array(npages, sizeof(struct page *), >>>> GFP_KERNEL); >>>> + vmas = kvmalloc_array(npages, sizeof(struct vm_area_struct *), >>>> + GFP_KERNEL); >>> This will result high order memory allocation which was what the code >>> tried to avoid originally. >>> >>> Using an unlimited size will cause a lot of side effects consider VM or >>> userspace may try to pin several TB of memory. >> Hmmm, that's a good point. Indeed, if the guest memory demand is huge or the >> host system is running short of free pages, kvmalloc will be problematic and >> less efficient than the __get_free_page implementation. > OK so ... Jason, what's the plan? > > How about you send a patchset with > 1. revert this change > 2. fix error handling leak
Work for me, but it looks like siwei want to do this.
So it's better for to send the patchset.
Thanks
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