Messages in this thread | | | Subject | Re: [PATCH v2 05/17] mm/frame-vector: Use FOLL_LONGTERM | From | John Hubbard <> | Date | Fri, 16 Oct 2020 00:54:18 -0700 |
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On 10/9/20 12:59 AM, Daniel Vetter wrote: ... > @@ -48,40 +47,25 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > > start = untagged_addr(start); > > - mmap_read_lock(mm); > - locked = 1; > - vma = find_vma_intersection(mm, start, start + 1); > - if (!vma) { > - ret = -EFAULT; > - goto out; > - } > - > - /* > - * While get_vaddr_frames() could be used for transient (kernel > - * controlled lifetime) pinning of memory pages all current > - * users establish long term (userspace controlled lifetime) > - * page pinning. Treat get_vaddr_frames() like > - * get_user_pages_longterm() and disallow it for filesystem-dax > - * mappings. > - */ > - if (vma_is_fsdax(vma)) { > - ret = -EOPNOTSUPP; > - goto out; > - } > - > - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { > + ret = pin_user_pages_fast(start, nr_frames, > + FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM, > + (struct page **)(vec->ptrs)); > + if (ret > 0) {
None of the callers that we have today will accept anything less than ret == nr_frames. And the whole partially pinned region idea turns out to be just not useful for almost everyone, from what I recall of the gup/pup call sites. So I wonder if we should just have get_vaddr_frames do the cleanup here and return -EFAULT, if ret != nr_frames ?
thanks, -- John Hubbard NVIDIA
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