On 11/04/2016 12:36 PM, Andrea Arcangeli wrote:
> On Thu, Nov 03, 2016 at 12:14:15PM -0700, Mike Kravetz wrote:
>> + /* lookup dst_addr as we may have copied some pages */
>> + dst_vma = find_vma(dst_mm, dst_addr);
>
> I put back dst_start here.
>
>> + if (dst_addr < dst_vma->vm_start ||
>> + dst_addr + len - (copied * vma_hpagesize) > dst_vma->vm_end)
>> + goto out_unlock;
>
> Actually this introduces a bug: copied * vma_hpagesize in the new
> patch is wrong, copied is already in byte units. I rolled back this
> one because of the dst_start commented above anyway.
>
>> + /*
>> + * Validate alignment based on huge page size
>> + */
>> + if (dst_addr & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
>> + goto out_unlock;
>
> If the vma changes under us we an as well fail. So I moved the
> alignment checks on dst_start/len before the retry loop and I added a
> further WARN_ON check inside the loop on dst_addr/len-copied just in
> case but that cannot trigger as we abort if the vma_hpagesize changed
> (hence WARN_ON).
>
> If we need to relax this later and handle a change of vma_hpagesize,
> it'll be backwards compatible change. I don't think it's needed and
> this is more strict behavior.
>
>> + while (src_addr < src_start + len) {
>> + pte_t dst_pteval;
>> +
>> + BUG_ON(dst_addr >= dst_start + len);
>> + dst_addr &= huge_page_mask(h);
>
> The additional mask is superflous here, it was already enforced by the
> alignment checks so I turned it into a bugcheck.
Thanks,
I had made similar hugetlb changes and was testing. I'll perform hugetlb
testing with the full diff patch below.
--
Mike Kravetz
>
> This is the current status, I'm sending a full diff against the
> previous submit for review of the latest updates. It's easier to
> review incrementally I think.
>
> Please test it, I updated the aa.git tree userfault branch in sync
> with this.
>
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index 063ccc7..8a0ee3ba 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -628,11 +628,11 @@ void mremap_userfaultfd_prep(struct vm_area_struct *vma,
> }
> }
>
> -void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx vm_ctx,
> +void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx,
> unsigned long from, unsigned long to,
> unsigned long len)
> {
> - struct userfaultfd_ctx *ctx = vm_ctx.ctx;
> + struct userfaultfd_ctx *ctx = vm_ctx->ctx;
> struct userfaultfd_wait_queue ewq;
>
> if (!ctx)
> @@ -657,6 +657,7 @@ void madvise_userfault_dontneed(struct vm_area_struct *vma,
> struct vm_area_struct **prev,
> unsigned long start, unsigned long end)
> {
> + struct mm_struct *mm = vma->vm_mm;
> struct userfaultfd_ctx *ctx;
> struct userfaultfd_wait_queue ewq;
>
> @@ -665,8 +666,9 @@ void madvise_userfault_dontneed(struct vm_area_struct *vma,
> return;
>
> userfaultfd_ctx_get(ctx);
> + up_read(&mm->mmap_sem);
> +
> *prev = NULL; /* We wait for ACK w/o the mmap semaphore */
> - up_read(&vma->vm_mm->mmap_sem);
>
> msg_init(&ewq.msg);
>
> @@ -676,7 +678,7 @@ void madvise_userfault_dontneed(struct vm_area_struct *vma,
>
> userfaultfd_event_wait_completion(ctx, &ewq);
>
> - down_read(&vma->vm_mm->mmap_sem);
> + down_read(&mm->mmap_sem);
> }
>
> static int userfaultfd_release(struct inode *inode, struct file *file)
> diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
> index 5caf97f..01a4e98 100644
> --- a/include/linux/userfaultfd_k.h
> +++ b/include/linux/userfaultfd_k.h
> @@ -77,7 +77,7 @@ extern void dup_userfaultfd_complete(struct list_head *);
>
> extern void mremap_userfaultfd_prep(struct vm_area_struct *,
> struct vm_userfaultfd_ctx *);
> -extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx,
> +extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
> unsigned long from, unsigned long to,
> unsigned long len);
>
> @@ -143,7 +143,7 @@ static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
> {
> }
>
> -static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx ctx,
> +static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
> unsigned long from,
> unsigned long to,
> unsigned long len)
> diff --git a/mm/mremap.c b/mm/mremap.c
> index 450e811..cef4967 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -592,6 +592,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
> up_write(¤t->mm->mmap_sem);
> if (locked && new_len > old_len)
> mm_populate(new_addr + old_len, new_len - old_len);
> - mremap_userfaultfd_complete(uf, addr, new_addr, old_len);
> + mremap_userfaultfd_complete(&uf, addr, new_addr, old_len);
> return ret;
> }
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 578622e..5d3e8bf 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1609,7 +1609,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
> if (fault_type) {
> *fault_type |= VM_FAULT_MAJOR;
> count_vm_event(PGMAJFAULT);
> - mem_cgroup_count_vm_event(vma->vm_mm,
> + mem_cgroup_count_vm_event(charge_mm,
> PGMAJFAULT);
> }
> /* Here we actually start the io */
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index d47b743..e8d7a89 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -172,8 +172,10 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> * by THP. Since we can not reliably insert a zero page, this
> * feature is not supported.
> */
> - if (zeropage)
> + if (zeropage) {
> + up_read(&dst_mm->mmap_sem);
> return -EINVAL;
> + }
>
> src_addr = src_start;
> dst_addr = dst_start;
> @@ -181,6 +183,12 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> page = NULL;
> vma_hpagesize = vma_kernel_pagesize(dst_vma);
>
> + /*
> + * Validate alignment based on huge page size
> + */
> + if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
> + goto out_unlock;
> +
> retry:
> /*
> * On routine entry dst_vma is set. If we had to drop mmap_sem and
> @@ -189,11 +197,15 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> err = -EINVAL;
> if (!dst_vma) {
> dst_vma = find_vma(dst_mm, dst_start);
> - vma_hpagesize = vma_kernel_pagesize(dst_vma);
> + if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
> + goto out_unlock;
> +
> + if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
> + goto out_unlock;
>
> /*
> - * Make sure the vma is not shared, that the dst range is
> - * both valid and fully within a single existing vma.
> + * Make sure the vma is not shared, that the remaining dst
> + * range is both valid and fully within a single existing vma.
> */
> if (dst_vma->vm_flags & VM_SHARED)
> goto out_unlock;
> @@ -202,10 +214,8 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> goto out_unlock;
> }
>
> - /*
> - * Validate alignment based on huge page size
> - */
> - if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
> + if (WARN_ON(dst_addr & (vma_hpagesize - 1) ||
> + (len - copied) & (vma_hpagesize - 1)))
> goto out_unlock;
>
> /*
> @@ -227,7 +237,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> pte_t dst_pteval;
>
> BUG_ON(dst_addr >= dst_start + len);
> - dst_addr &= huge_page_mask(h);
> + VM_BUG_ON(dst_addr & ~huge_page_mask(h));
>
> /*
> * Serialize via hugetlb_fault_mutex
> @@ -300,17 +310,13 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> return copied ? copied : err;
> }
> #else /* !CONFIG_HUGETLB_PAGE */
> -static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> - struct vm_area_struct *dst_vma,
> - unsigned long dst_start,
> - unsigned long src_start,
> - unsigned long len,
> - bool zeropage)
> -{
> - up_read(&dst_mm->mmap_sem); /* HUGETLB not configured */
> - BUG();
> - return -EINVAL;
> -}
> +/* fail at build time if gcc attempts to use this */
> +extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> + struct vm_area_struct *dst_vma,
> + unsigned long dst_start,
> + unsigned long src_start,
> + unsigned long len,
> + bool zeropage);
> #endif /* CONFIG_HUGETLB_PAGE */
>
> static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
> @@ -360,9 +366,9 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
> /*
> * If this is a HUGETLB vma, pass off to appropriate routine
> */
> - if (dst_vma->vm_flags & VM_HUGETLB)
> + if (is_vm_hugetlb_page(dst_vma))
> return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
> - src_start, len, false);
> + src_start, len, zeropage);
>
> /*
> * Be strict and only allow __mcopy_atomic on userfaultfd
> @@ -431,8 +437,11 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
> err = mfill_zeropage_pte(dst_mm, dst_pmd,
> dst_vma, dst_addr);
> } else {
> - err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
> - dst_addr, src_addr, &page);
> + err = -EINVAL; /* if zeropage is true return -EINVAL */
> + if (likely(!zeropage))
> + err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd,
> + dst_vma, dst_addr,
> + src_addr, &page);
> }
>
> cond_resched();
> diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
> index fed2119..5a840a6 100644
> --- a/tools/testing/selftests/vm/userfaultfd.c
> +++ b/tools/testing/selftests/vm/userfaultfd.c
> @@ -625,6 +625,86 @@ static int faulting_process(void)
> return 0;
> }
>
> +static int uffdio_zeropage(int ufd, unsigned long offset)
> +{
> + struct uffdio_zeropage uffdio_zeropage;
> + int ret;
> + unsigned long has_zeropage = EXPECTED_IOCTLS & (1 << _UFFDIO_ZEROPAGE);
> +
> + if (offset >= nr_pages * page_size)
> + fprintf(stderr, "unexpected offset %lu\n",
> + offset), exit(1);
> + uffdio_zeropage.range.start = (unsigned long) area_dst + offset;
> + uffdio_zeropage.range.len = page_size;
> + uffdio_zeropage.mode = 0;
> + ret = ioctl(ufd, UFFDIO_ZEROPAGE, &uffdio_zeropage);
> + if (ret) {
> + /* real retval in ufdio_zeropage.zeropage */
> + if (has_zeropage) {
> + if (uffdio_zeropage.zeropage == -EEXIST)
> + fprintf(stderr, "UFFDIO_ZEROPAGE -EEXIST\n"),
> + exit(1);
> + else
> + fprintf(stderr, "UFFDIO_ZEROPAGE error %Ld\n",
> + uffdio_zeropage.zeropage), exit(1);
> + } else {
> + if (uffdio_zeropage.zeropage != -EINVAL)
> + fprintf(stderr,
> + "UFFDIO_ZEROPAGE not -EINVAL %Ld\n",
> + uffdio_zeropage.zeropage), exit(1);
> + }
> + } else if (has_zeropage) {
> + if (uffdio_zeropage.zeropage != page_size) {
> + fprintf(stderr, "UFFDIO_ZEROPAGE unexpected %Ld\n",
> + uffdio_zeropage.zeropage), exit(1);
> + } else
> + return 1;
> + } else {
> + fprintf(stderr,
> + "UFFDIO_ZEROPAGE succeeded %Ld\n",
> + uffdio_zeropage.zeropage), exit(1);
> + }
> +
> + return 0;
> +}
> +
> +/* exercise UFFDIO_ZEROPAGE */
> +static int userfaultfd_zeropage_test(void)
> +{
> + struct uffdio_register uffdio_register;
> + unsigned long expected_ioctls;
> +
> + printf("testing UFFDIO_ZEROPAGE: ");
> + fflush(stdout);
> +
> + if (release_pages(area_dst))
> + return 1;
> +
> + if (userfaultfd_open(0) < 0)
> + return 1;
> + uffdio_register.range.start = (unsigned long) area_dst;
> + uffdio_register.range.len = nr_pages * page_size;
> + uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
> + if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
> + fprintf(stderr, "register failure\n"), exit(1);
> +
> + expected_ioctls = EXPECTED_IOCTLS;
> + if ((uffdio_register.ioctls & expected_ioctls) !=
> + expected_ioctls)
> + fprintf(stderr,
> + "unexpected missing ioctl for anon memory\n"),
> + exit(1);
> +
> + if (uffdio_zeropage(uffd, 0)) {
> + if (my_bcmp(area_dst, zeropage, page_size))
> + fprintf(stderr, "zeropage is not zero\n"), exit(1);
> + }
> +
> + close(uffd);
> + printf("done.\n");
> + return 0;
> +}
> +
> static int userfaultfd_events_test(void)
> {
> struct uffdio_register uffdio_register;
> @@ -679,6 +759,7 @@ static int userfaultfd_events_test(void)
> if (pthread_join(uffd_mon, (void **)&userfaults))
> return 1;
>
> + close(uffd);
> printf("userfaults: %ld\n", userfaults);
>
> return userfaults != nr_pages;
> @@ -852,7 +933,7 @@ static int userfaultfd_stress(void)
> return err;
>
> close(uffd);
> - return userfaultfd_events_test();
> + return userfaultfd_zeropage_test() || userfaultfd_events_test();
> }
>
> #ifndef HUGETLB_TEST
>
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