On 8/9/19 3:58 PM, ira.weiny@xxxxxxxxx wrote:
> From: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> The addition of FOLL_LONGTERM has taken on additional meaning for CMA
> pages.
>
> In addition subsystems such as RDMA require new information to be passed
> to the GUP interface to track file owning information. As such a simple
> FOLL_LONGTERM flag is no longer sufficient for these users to pin pages.
>
> Introduce a new GUP like call which takes the newly introduced vaddr_pin
> information. Failure to pass the vaddr_pin object back to a vaddr_put*
> call will result in a failure if pins were created on files during the
> pin operation.
>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> ---
> Changes from list:
> Change to vaddr_put_pages_dirty_lock
> Change to vaddr_unpin_pages_dirty_lock
>
> include/linux/mm.h | 5 ++++
> mm/gup.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 64 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 657c947bda49..90c5802866df 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1603,6 +1603,11 @@ int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc);
> int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
> struct task_struct *task, bool bypass_rlim);
>
> +long vaddr_pin_pages(unsigned long addr, unsigned long nr_pages,
> + unsigned int gup_flags, struct page **pages,
> + struct vaddr_pin *vaddr_pin);
> +void vaddr_unpin_pages_dirty_lock(struct page **pages, unsigned long nr_pages,
> + struct vaddr_pin *vaddr_pin, bool make_dirty);
Hi Ira,
OK, the API seems fine to me, anyway. :)
A bit more below...
> bool mapping_inode_has_layout(struct vaddr_pin *vaddr_pin, struct page *page);
>
> /* Container for pinned pfns / pages */
> diff --git a/mm/gup.c b/mm/gup.c
> index eeaa0ddd08a6..6d23f70d7847 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2536,3 +2536,62 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
> return ret;
> }
> EXPORT_SYMBOL_GPL(get_user_pages_fast);
> +
> +/**
> + * vaddr_pin_pages pin pages by virtual address and return the pages to the
> + * user.
> + *
> + * @addr, start address
What's with the commas? I thought kernel-doc wants colons, like this, right?
@addr: start address
> + * @nr_pages, number of pages to pin
> + * @gup_flags, flags to use for the pin
> + * @pages, array of pages returned
> + * @vaddr_pin, initalized meta information this pin is to be associated
> + * with.
> + *
> + * NOTE regarding vaddr_pin:
> + *
> + * Some callers can share pins via file descriptors to other processes.
> + * Callers such as this should use the f_owner field of vaddr_pin to indicate
> + * the file the fd points to. All other callers should use the mm this pin is
> + * being made against. Usually "current->mm".
> + *
> + * Expects mmap_sem to be read locked.
> + */
> +long vaddr_pin_pages(unsigned long addr, unsigned long nr_pages,
> + unsigned int gup_flags, struct page **pages,
> + struct vaddr_pin *vaddr_pin)
> +{
> + long ret;
> +
> + gup_flags |= FOLL_LONGTERM;
Is now the right time to introduce and use FOLL_PIN? If not, then I can always
add it on top of this later, as part of gup-tracking patches. But you did point
out that FOLL_LONGTERM is taking on additional meaning, and so maybe it's better
to split that meaning up right from the start.
> +
> + if (!vaddr_pin || (!vaddr_pin->mm && !vaddr_pin->f_owner))
> + return -EINVAL;
> +
> + ret = __gup_longterm_locked(current,
> + vaddr_pin->mm,
> + addr, nr_pages,
> + pages, NULL, gup_flags,
> + vaddr_pin);
> + return ret;
> +}
> +EXPORT_SYMBOL(vaddr_pin_pages);
> +
> +/**
> + * vaddr_unpin_pages_dirty_lock - counterpart to vaddr_pin_pages
> + *
> + * @pages, array of pages returned
> + * @nr_pages, number of pages in pages
> + * @vaddr_pin, same information passed to vaddr_pin_pages
> + * @make_dirty: whether to mark the pages dirty
> + *
> + * The semantics are similar to put_user_pages_dirty_lock but a vaddr_pin used
> + * in vaddr_pin_pages should be passed back into this call for propper
Typo:
proper
> + * tracking.
> + */
> +void vaddr_unpin_pages_dirty_lock(struct page **pages, unsigned long nr_pages,
> + struct vaddr_pin *vaddr_pin, bool make_dirty)
> +{
> + __put_user_pages_dirty_lock(vaddr_pin, pages, nr_pages, make_dirty);
> +}
> +EXPORT_SYMBOL(vaddr_unpin_pages_dirty_lock);
>
OK, whew, I'm glad to see the updated _dirty_lock() API used here. :)
thanks,
--
John Hubbard
NVIDIA
