userfaultfd: hugetlbfs: add __mcopy_atomic_hugetlb for huge page UFFDIO_COPY
__mcopy_atomic_hugetlb performs the UFFDIO_COPY operation for huge pages. It is based on the existing __mcopy_atomic routine for normal pages. Unlike normal pages, there is no huge page support for the UFFDIO_ZEROPAGE operation. Link: http://lkml.kernel.org/r/20161216144821.5183-19-aarcange@redhat.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michael Rapoport <RAPOPORT@il.ibm.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz
Linus Torvalds
parent
8fb5debc5f
commit
60d4d2d2b4
1 changed files with 186 additions and 0 deletions
186
mm/userfaultfd.c
186
mm/userfaultfd.c
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@ -14,6 +14,8 @@
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#include <linux/swapops.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/mmu_notifier.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <asm/tlbflush.h>
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#include "internal.h"
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@ -139,6 +141,183 @@ static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
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return pmd;
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}
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#ifdef CONFIG_HUGETLB_PAGE
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/*
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* __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
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* called with mmap_sem held, it will release mmap_sem before returning.
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*/
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static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
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struct vm_area_struct *dst_vma,
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unsigned long dst_start,
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unsigned long src_start,
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unsigned long len,
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bool zeropage)
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{
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ssize_t err;
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pte_t *dst_pte;
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unsigned long src_addr, dst_addr;
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long copied;
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struct page *page;
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struct hstate *h;
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unsigned long vma_hpagesize;
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pgoff_t idx;
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u32 hash;
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struct address_space *mapping;
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/*
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* There is no default zero huge page for all huge page sizes as
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* supported by hugetlb. A PMD_SIZE huge pages may exist as used
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* by THP. Since we can not reliably insert a zero page, this
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* feature is not supported.
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*/
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if (zeropage) {
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up_read(&dst_mm->mmap_sem);
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return -EINVAL;
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}
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src_addr = src_start;
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dst_addr = dst_start;
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copied = 0;
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page = NULL;
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vma_hpagesize = vma_kernel_pagesize(dst_vma);
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/*
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* Validate alignment based on huge page size
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*/
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err = -EINVAL;
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if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
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goto out_unlock;
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retry:
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/*
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* On routine entry dst_vma is set. If we had to drop mmap_sem and
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* retry, dst_vma will be set to NULL and we must lookup again.
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*/
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if (!dst_vma) {
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err = -EINVAL;
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dst_vma = find_vma(dst_mm, dst_start);
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if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
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goto out_unlock;
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if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
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goto out_unlock;
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/*
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* Make sure the vma is not shared, that the remaining dst
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* range is both valid and fully within a single existing vma.
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*/
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if (dst_vma->vm_flags & VM_SHARED)
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goto out_unlock;
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if (dst_start < dst_vma->vm_start ||
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dst_start + len > dst_vma->vm_end)
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goto out_unlock;
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}
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if (WARN_ON(dst_addr & (vma_hpagesize - 1) ||
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(len - copied) & (vma_hpagesize - 1)))
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goto out_unlock;
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/*
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* Only allow __mcopy_atomic_hugetlb on userfaultfd registered ranges.
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*/
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if (!dst_vma->vm_userfaultfd_ctx.ctx)
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goto out_unlock;
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/*
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* Ensure the dst_vma has a anon_vma.
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*/
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err = -ENOMEM;
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if (unlikely(anon_vma_prepare(dst_vma)))
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goto out_unlock;
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h = hstate_vma(dst_vma);
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while (src_addr < src_start + len) {
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pte_t dst_pteval;
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BUG_ON(dst_addr >= dst_start + len);
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VM_BUG_ON(dst_addr & ~huge_page_mask(h));
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/*
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* Serialize via hugetlb_fault_mutex
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*/
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idx = linear_page_index(dst_vma, dst_addr);
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mapping = dst_vma->vm_file->f_mapping;
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hash = hugetlb_fault_mutex_hash(h, dst_mm, dst_vma, mapping,
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idx, dst_addr);
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mutex_lock(&hugetlb_fault_mutex_table[hash]);
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err = -ENOMEM;
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dst_pte = huge_pte_alloc(dst_mm, dst_addr, huge_page_size(h));
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if (!dst_pte) {
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mutex_unlock(&hugetlb_fault_mutex_table[hash]);
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goto out_unlock;
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}
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err = -EEXIST;
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dst_pteval = huge_ptep_get(dst_pte);
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if (!huge_pte_none(dst_pteval)) {
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mutex_unlock(&hugetlb_fault_mutex_table[hash]);
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goto out_unlock;
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}
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err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
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dst_addr, src_addr, &page);
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mutex_unlock(&hugetlb_fault_mutex_table[hash]);
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cond_resched();
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if (unlikely(err == -EFAULT)) {
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up_read(&dst_mm->mmap_sem);
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BUG_ON(!page);
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err = copy_huge_page_from_user(page,
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(const void __user *)src_addr,
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pages_per_huge_page(h));
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if (unlikely(err)) {
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err = -EFAULT;
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goto out;
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}
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down_read(&dst_mm->mmap_sem);
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dst_vma = NULL;
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goto retry;
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} else
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BUG_ON(page);
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if (!err) {
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dst_addr += vma_hpagesize;
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src_addr += vma_hpagesize;
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copied += vma_hpagesize;
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if (fatal_signal_pending(current))
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err = -EINTR;
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}
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if (err)
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break;
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}
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out_unlock:
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up_read(&dst_mm->mmap_sem);
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out:
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if (page)
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put_page(page);
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BUG_ON(copied < 0);
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BUG_ON(err > 0);
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BUG_ON(!copied && !err);
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return copied ? copied : err;
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}
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#else /* !CONFIG_HUGETLB_PAGE */
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/* fail at build time if gcc attempts to use this */
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extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
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struct vm_area_struct *dst_vma,
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unsigned long dst_start,
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unsigned long src_start,
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unsigned long len,
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bool zeropage);
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#endif /* CONFIG_HUGETLB_PAGE */
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static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
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unsigned long dst_start,
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unsigned long src_start,
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@ -181,6 +360,13 @@ retry:
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dst_start + len > dst_vma->vm_end)
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goto out_unlock;
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/*
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* If this is a HUGETLB vma, pass off to appropriate routine
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*/
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if (is_vm_hugetlb_page(dst_vma))
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return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
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src_start, len, zeropage);
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/*
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* Be strict and only allow __mcopy_atomic on userfaultfd
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* registered ranges to prevent userland errors going
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