On Tue, Jan 15, 2019 at 10:12:58AM -0800, Davidlohr Bueso wrote:
> This driver already uses gup_fast() and thus we can just drop
> the mmap_sem protection around the pinned_vm counter. Note that
> the window between when hfi1_can_pin_pages() is called and the
> actual counter is incremented remains the same as mmap_sem was
> _only_ used for when ->pinned_vm was touched.
>
> Cc: mike.marciniszyn@xxxxxxxxx
> Cc: dennis.dalessandro@xxxxxxxxx
> Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> ---
> drivers/infiniband/hw/hfi1/user_pages.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/drivers/infiniband/hw/hfi1/user_pages.c b/drivers/infiniband/hw/hfi1/user_pages.c
> index df86a596d746..f0c6f219f575 100644
> --- a/drivers/infiniband/hw/hfi1/user_pages.c
> +++ b/drivers/infiniband/hw/hfi1/user_pages.c
> @@ -91,9 +91,7 @@ bool hfi1_can_pin_pages(struct hfi1_devdata *dd, struct mm_struct *mm,
> /* Convert to number of pages */
> size = DIV_ROUND_UP(size, PAGE_SIZE);
>
> - down_read(&mm->mmap_sem);
> pinned = atomic_long_read(&mm->pinned_vm);
> - up_read(&mm->mmap_sem);
>
> /* First, check the absolute limit against all pinned pages. */
> if (pinned + npages >= ulimit && !can_lock)
> @@ -111,9 +109,7 @@ int hfi1_acquire_user_pages(struct mm_struct *mm, unsigned long vaddr, size_t np
> if (ret < 0)
> return ret;
>
> - down_write(&mm->mmap_sem);
> atomic_long_add(ret, &mm->pinned_vm);
> - up_write(&mm->mmap_sem);
>
> return ret;
> }
> @@ -130,8 +126,6 @@ void hfi1_release_user_pages(struct mm_struct *mm, struct page **p,
> }
>
> if (mm) { /* during close after signal, mm can be NULL */
> - down_write(&mm->mmap_sem);
> atomic_long_sub(npages, &mm->pinned_vm);
> - up_write(&mm->mmap_sem);
> }
> }
> --
> 2.16.4
>
