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Date: Tue, 3 Nov 2020 16:53:43 +0800
From: Jason Wang <jasowang@...hat.com>
To: Si-Wei Liu <si-wei.liu@...cle.com>, mst@...hat.com,
lingshan.zhu@...el.com
Cc: joao.m.martins@...cle.com, boris.ostrovsky@...cle.com,
linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 1/2] Revert "vhost-vdpa: fix page pinning leakage in error
path"
On 2020/10/30 下午3:45, Si-Wei Liu wrote:
> This reverts commit 7ed9e3d97c32d969caded2dfb6e67c1a2cc5a0b1.
>
> Signed-off-by: Si-Wei Liu <si-wei.liu@...cle.com>
> ---
> drivers/vhost/vdpa.c | 119 +++++++++++++++++++++------------------------------
> 1 file changed, 48 insertions(+), 71 deletions(-)
I saw this has been reverted there
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/vhost?id=5e1a3149eec8675c2767cc465903f5e4829de5b0.
:)
Thanks
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index a2dbc85..b6d9016 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -588,19 +588,21 @@ 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;
> - struct vm_area_struct **vmas;
> + unsigned long list_size = PAGE_SIZE / sizeof(struct page *);
> unsigned int gup_flags = FOLL_LONGTERM;
> - unsigned long map_pfn, last_pfn = 0;
> - unsigned long npages, lock_limit;
> - unsigned long i, nmap = 0;
> + unsigned long npages, cur_base, map_pfn, last_pfn = 0;
> + unsigned long locked, lock_limit, pinned, i;
> 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;
>
> @@ -608,86 +610,61 @@ 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);
> - if (!page_list || !vmas) {
> - ret = -ENOMEM;
> - goto free;
> - }
> -
> mmap_read_lock(dev->mm);
>
> + locked = atomic64_add_return(npages, &dev->mm->pinned_vm);
> lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> - if (npages + atomic64_read(&dev->mm->pinned_vm) > lock_limit) {
> - ret = -ENOMEM;
> - goto unlock;
> - }
>
> - pinned = pin_user_pages(msg->uaddr & PAGE_MASK, npages, gup_flags,
> - page_list, vmas);
> - if (npages != pinned) {
> - if (pinned < 0) {
> - ret = pinned;
> - } else {
> - unpin_user_pages(page_list, pinned);
> - ret = -ENOMEM;
> - }
> - goto unlock;
> + if (locked > lock_limit) {
> + ret = -ENOMEM;
> + goto out;
> }
>
> + cur_base = msg->uaddr & PAGE_MASK;
> iova &= PAGE_MASK;
> - map_pfn = page_to_pfn(page_list[0]);
> -
> - /* One more iteration to avoid extra vdpa_map() call out of loop. */
> - for (i = 0; i <= npages; i++) {
> - unsigned long this_pfn;
> - u64 csize;
> -
> - /* The last chunk may have no valid PFN next to it */
> - this_pfn = i < npages ? page_to_pfn(page_list[i]) : -1UL;
> -
> - if (last_pfn && (this_pfn == -1UL ||
> - this_pfn != last_pfn + 1)) {
> - /* Pin a contiguous chunk of memory */
> - csize = last_pfn - map_pfn + 1;
> - ret = vhost_vdpa_map(v, iova, csize << PAGE_SHIFT,
> - map_pfn << PAGE_SHIFT,
> - msg->perm);
> - if (ret) {
> - /*
> - * Unpin the rest chunks of memory on the
> - * flight with no corresponding vdpa_map()
> - * calls having been made yet. On the other
> - * hand, vdpa_unmap() in the failure path
> - * is in charge of accounting the number of
> - * pinned pages for its own.
> - * This asymmetrical pattern of accounting
> - * is for efficiency to pin all pages at
> - * once, while there is no other callsite
> - * of vdpa_map() than here above.
> - */
> - unpin_user_pages(&page_list[nmap],
> - npages - nmap);
> - goto out;
> +
> + while (npages) {
> + pinned = min_t(unsigned long, npages, list_size);
> + ret = pin_user_pages(cur_base, pinned,
> + gup_flags, page_list, NULL);
> + if (ret != pinned)
> + goto out;
> +
> + if (!last_pfn)
> + map_pfn = page_to_pfn(page_list[0]);
> +
> + for (i = 0; i < ret; i++) {
> + unsigned long this_pfn = page_to_pfn(page_list[i]);
> + u64 csize;
> +
> + if (last_pfn && (this_pfn != last_pfn + 1)) {
> + /* Pin a contiguous chunk of memory */
> + csize = (last_pfn - map_pfn + 1) << PAGE_SHIFT;
> + if (vhost_vdpa_map(v, iova, csize,
> + map_pfn << PAGE_SHIFT,
> + msg->perm))
> + goto out;
> + map_pfn = this_pfn;
> + iova += csize;
> }
> - atomic64_add(csize, &dev->mm->pinned_vm);
> - nmap += csize;
> - iova += csize << PAGE_SHIFT;
> - map_pfn = this_pfn;
> +
> + last_pfn = this_pfn;
> }
> - last_pfn = this_pfn;
> +
> + cur_base += ret << PAGE_SHIFT;
> + npages -= ret;
> }
>
> - WARN_ON(nmap != npages);
> + /* Pin the rest chunk */
> + ret = vhost_vdpa_map(v, iova, (last_pfn - map_pfn + 1) << PAGE_SHIFT,
> + map_pfn << PAGE_SHIFT, msg->perm);
> out:
> - if (ret)
> + if (ret) {
> vhost_vdpa_unmap(v, msg->iova, msg->size);
> -unlock:
> + atomic64_sub(npages, &dev->mm->pinned_vm);
> + }
> mmap_read_unlock(dev->mm);
> -free:
> - kvfree(vmas);
> - kvfree(page_list);
> + free_page((unsigned long)page_list);
> return ret;
> }
>
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