diff options
| author | Andrea Arcangeli <aarcange@redhat.com> | 2017-02-22 15:43:13 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-22 16:41:28 -0800 |
| commit | 87ffc118b54dcd4cc642723603d944673248152f (patch) | |
| tree | ef5ff9a70c12b331985148ebab7629a73984c841 /mm/hugetlb.c | |
| parent | 369cd2121be440543280b91056de187f625d0dbb (diff) | |
| download | linux-87ffc118b54dcd4cc642723603d944673248152f.tar.bz2 | |
userfaultfd: hugetlbfs: gup: support VM_FAULT_RETRY
Add support for VM_FAULT_RETRY to follow_hugetlb_page() so that
get_user_pages_unlocked/locked and "nonblocking/FOLL_NOWAIT" features
will work on hugetlbfs.
This is required for fully functional userfaultfd non-present support on
hugetlbfs.
Link: http://lkml.kernel.org/r/20161216144821.5183-25-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.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>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 48 |
1 files changed, 40 insertions, 8 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a4b29054cc3f..f6c7ff316daf 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4065,7 +4065,7 @@ out_release_unlock: long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, struct page **pages, struct vm_area_struct **vmas, unsigned long *position, unsigned long *nr_pages, - long i, unsigned int flags) + long i, unsigned int flags, int *nonblocking) { unsigned long pfn_offset; unsigned long vaddr = *position; @@ -4128,16 +4128,43 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, ((flags & FOLL_WRITE) && !huge_pte_write(huge_ptep_get(pte)))) { int ret; + unsigned int fault_flags = 0; if (pte) spin_unlock(ptl); - ret = hugetlb_fault(mm, vma, vaddr, - (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); - if (!(ret & VM_FAULT_ERROR)) - continue; - - remainder = 0; - break; + if (flags & FOLL_WRITE) + fault_flags |= FAULT_FLAG_WRITE; + if (nonblocking) + fault_flags |= FAULT_FLAG_ALLOW_RETRY; + if (flags & FOLL_NOWAIT) + fault_flags |= FAULT_FLAG_ALLOW_RETRY | + FAULT_FLAG_RETRY_NOWAIT; + if (flags & FOLL_TRIED) { + VM_WARN_ON_ONCE(fault_flags & + FAULT_FLAG_ALLOW_RETRY); + fault_flags |= FAULT_FLAG_TRIED; + } + ret = hugetlb_fault(mm, vma, vaddr, fault_flags); + if (ret & VM_FAULT_ERROR) { + remainder = 0; + break; + } + if (ret & VM_FAULT_RETRY) { + if (nonblocking) + *nonblocking = 0; + *nr_pages = 0; + /* + * VM_FAULT_RETRY must not return an + * error, it will return zero + * instead. + * + * No need to update "position" as the + * caller will not check it after + * *nr_pages is set to 0. + */ + return i; + } + continue; } pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; @@ -4166,6 +4193,11 @@ same_page: spin_unlock(ptl); } *nr_pages = remainder; + /* + * setting position is actually required only if remainder is + * not zero but it's faster not to add a "if (remainder)" + * branch. + */ *position = vaddr; return i ? i : -EFAULT; |