From: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Subject: userfaultfd: hugetlbfs: userfaultfd_huge_must_wait for hugepmd ranges Add routine userfaultfd_huge_must_wait which has the same functionality as the existing userfaultfd_must_wait routine. Only difference is that new routine must handle page table structure for hugepmd vmas. Link: http://lkml.kernel.org/r/20161216144821.5183-24-aarcange@xxxxxxxxxx Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/userfaultfd.c | 51 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 49 insertions(+), 2 deletions(-) diff -puN fs/userfaultfd.c~userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges fs/userfaultfd.c --- a/fs/userfaultfd.c~userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges +++ a/fs/userfaultfd.c @@ -202,6 +202,49 @@ static inline struct uffd_msg userfault_ return msg; } +#ifdef CONFIG_HUGETLB_PAGE +/* + * Same functionality as userfaultfd_must_wait below with modifications for + * hugepmd ranges. + */ +static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, + unsigned long address, + unsigned long flags, + unsigned long reason) +{ + struct mm_struct *mm = ctx->mm; + pte_t *pte; + bool ret = true; + + VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); + + pte = huge_pte_offset(mm, address); + if (!pte) + goto out; + + ret = false; + + /* + * Lockless access: we're in a wait_event so it's ok if it + * changes under us. + */ + if (huge_pte_none(*pte)) + ret = true; + if (!huge_pte_write(*pte) && (reason & VM_UFFD_WP)) + ret = true; +out: + return ret; +} +#else +static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, + unsigned long address, + unsigned long flags, + unsigned long reason) +{ + return false; /* should never get here */ +} +#endif /* CONFIG_HUGETLB_PAGE */ + /* * Verify the pagetables are still not ok after having reigstered into * the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any @@ -378,8 +421,12 @@ int handle_userfault(struct vm_fault *vm set_current_state(blocking_state); spin_unlock(&ctx->fault_pending_wqh.lock); - must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, - reason); + if (!is_vm_hugetlb_page(vmf->vma)) + must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, + reason); + else + must_wait = userfaultfd_huge_must_wait(ctx, vmf->address, + vmf->flags, reason); up_read(&mm->mmap_sem); if (likely(must_wait && !ACCESS_ONCE(ctx->released) && _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
