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userfaultfd: hugetlbfs: userfaultfd_huge_must_wait for hugepmd ranges

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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@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 2017-02-22 15:43:10 -08:00 committed by Linus Torvalds
parent 9903bd7b73
commit 369cd2121b
1 changed files with 49 additions and 2 deletions
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51
fs/userfaultfd.c
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@ -202,6 +202,49 @@ static inline struct uffd_msg userfault_msg(unsigned long address,
return msg; 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 * Verify the pagetables are still not ok after having reigstered into
* the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any * the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any
@ -378,8 +421,12 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
set_current_state(blocking_state); set_current_state(blocking_state);
spin_unlock(&ctx->fault_pending_wqh.lock); spin_unlock(&ctx->fault_pending_wqh.lock);
must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, if (!is_vm_hugetlb_page(vmf->vma))
reason); 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); up_read(&mm->mmap_sem);
if (likely(must_wait && !ACCESS_ONCE(ctx->released) && if (likely(must_wait && !ACCESS_ONCE(ctx->released) &&