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SubjectRe: [PATCH v9 05/24] mm: Introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
On Tue, 13 Mar 2018, Laurent Dufour wrote:

> When handling page fault without holding the mmap_sem the fetch of the
> pte lock pointer and the locking will have to be done while ensuring
> that the VMA is not touched in our back.
>
> So move the fetch and locking operations in a dedicated function.
>
> Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
> ---
> mm/memory.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 8ac241b9f370..21b1212a0892 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2288,6 +2288,13 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
> }
> EXPORT_SYMBOL_GPL(apply_to_page_range);
>
> +static bool pte_spinlock(struct vm_fault *vmf)

inline?

> +{
> + vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
> + spin_lock(vmf->ptl);
> + return true;
> +}
> +
> static bool pte_map_lock(struct vm_fault *vmf)
> {
> vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,

Shouldn't pte_unmap_same() take struct vm_fault * and use the new
pte_spinlock()?

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