From: Ira Weiny <ira.weiny@intel.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>, Theodore Ts'o <tytso@mit.edu>,
linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org,
Dave Chinner <david@fromorbit.com>,
linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
linux-xfs@vger.kernel.org, Jason Gunthorpe <jgg@ziepe.ca>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-ext4@vger.kernel.org
Subject: Re: [RFC PATCH v2 15/19] mm/gup: Introduce vaddr_pin_pages()
Date: Mon, 12 Aug 2019 14:00:14 -0700 [thread overview]
Message-ID: <20190812210013.GC20634@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <6ed26a08-4371-9dc1-09eb-7b8a4689d93b@nvidia.com>
On Fri, Aug 09, 2019 at 05:09:54PM -0700, John Hubbard wrote:
> On 8/9/19 3:58 PM, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> >
> > 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@intel.com>
> >
> > ---
> > 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
:-/ I don't know.
Fixed.
>
>
> > + * @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.
>
At one point I wanted to (and had in my tree) a new flag but I went away from
it. Prior to the discussion on mlock last week I did not think we needed it.
But I'm ok to add it back in.
I was not ignoring the idea for this RFC I just wanted to get this out there
for people to see. I see that you threw out a couple of patches which add this
flag in.
FWIW, I think it would be good to differentiate between an indefinite pinned
page vs a referenced "gotten" page.
What you and I have been working on is the former. So it would be easy to
change your refcounting patches to simply key off of FOLL_PIN.
Would you like me to add in your FOLL_PIN patches to this series?
>
> > +
> > + 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
Fixed.
>
> > + * 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. :)
Yea this was pretty easy to change during the rebase. Again I'm kind of
floating these quickly at this point. So sorry about the nits...
Ira
>
> thanks,
> --
> John Hubbard
> NVIDIA
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next prev parent reply other threads:[~2019-08-12 21:02 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 22:58 [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 01/19] fs/locks: Export F_LAYOUT lease to user space ira.weiny
2019-08-09 23:52 ` Dave Chinner
2019-08-12 17:36 ` Ira Weiny
2019-08-14 8:05 ` Dave Chinner
2019-08-14 11:21 ` Jeff Layton
2019-08-14 11:38 ` Dave Chinner
2019-08-09 22:58 ` [RFC PATCH v2 02/19] fs/locks: Add Exclusive flag to user Layout lease ira.weiny
2019-08-14 14:15 ` Jeff Layton
2019-08-14 21:56 ` Dave Chinner
2019-08-26 10:41 ` Jeff Layton
2019-08-29 23:34 ` Ira Weiny
2019-09-04 12:52 ` Jeff Layton
2019-09-04 23:12 ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 03/19] mm/gup: Pass flags down to __gup_device_huge* calls ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 04/19] mm/gup: Ensure F_LAYOUT lease is held prior to GUP'ing pages ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 05/19] fs/ext4: Teach ext4 to break layout leases ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 06/19] fs/ext4: Teach dax_layout_busy_page() to operate on a sub-range ira.weiny
2019-08-23 15:18 ` Vivek Goyal
2019-08-29 18:52 ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 07/19] fs/xfs: Teach xfs to use new dax_layout_busy_page() ira.weiny
2019-08-09 23:30 ` Dave Chinner
2019-08-12 18:05 ` Ira Weiny
2019-08-14 8:04 ` Dave Chinner
2019-08-09 22:58 ` [RFC PATCH v2 08/19] fs/xfs: Fail truncate if page lease can't be broken ira.weiny
2019-08-09 23:22 ` Dave Chinner
2019-08-12 18:08 ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 09/19] mm/gup: Introduce vaddr_pin structure ira.weiny
2019-08-10 0:06 ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 10/19] mm/gup: Pass a NULL vaddr_pin through GUP fast ira.weiny
2019-08-10 0:06 ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 11/19] mm/gup: Pass follow_page_context further down the call stack ira.weiny
2019-08-10 0:18 ` John Hubbard
2019-08-12 19:01 ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 12/19] mm/gup: Prep put_user_pages() to take an vaddr_pin struct ira.weiny
2019-08-10 0:30 ` John Hubbard
2019-08-12 20:46 ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 13/19] {mm,file}: Add file_pins objects ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 14/19] fs/locks: Associate file pins while performing GUP ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 15/19] mm/gup: Introduce vaddr_pin_pages() ira.weiny
2019-08-10 0:09 ` John Hubbard
2019-08-12 21:00 ` Ira Weiny [this message]
2019-08-12 21:20 ` John Hubbard
2019-08-11 23:07 ` John Hubbard
2019-08-12 21:01 ` Ira Weiny
2019-08-12 12:28 ` Jason Gunthorpe
2019-08-12 21:48 ` Ira Weiny
2019-08-13 11:47 ` Jason Gunthorpe
2019-08-13 17:46 ` Ira Weiny
2019-08-13 17:56 ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 16/19] RDMA/uverbs: Add back pointer to system file object ira.weiny
2019-08-12 13:00 ` Jason Gunthorpe
2019-08-12 17:28 ` Ira Weiny
2019-08-12 17:56 ` Jason Gunthorpe
2019-08-12 21:15 ` Ira Weiny
2019-08-13 11:48 ` Jason Gunthorpe
2019-08-13 17:41 ` Ira Weiny
2019-08-13 18:00 ` Jason Gunthorpe
2019-08-13 20:38 ` Ira Weiny
2019-08-14 12:23 ` Jason Gunthorpe
2019-08-14 17:50 ` Ira Weiny
2019-08-14 18:15 ` Jason Gunthorpe
2019-09-04 22:25 ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 17/19] RDMA/umem: Convert to vaddr_[pin|unpin]* operations ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 18/19] {mm,procfs}: Add display file_pins proc ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 19/19] mm/gup: Remove FOLL_LONGTERM DAX exclusion ira.weiny
2019-08-14 10:17 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jan Kara
2019-08-14 18:08 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Ira Weiny
2019-08-15 13:05 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jan Kara
2019-08-16 19:05 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Ira Weiny
2019-08-16 23:20 ` Ira Weiny
2019-08-19 6:36 ` Jan Kara
2019-08-17 2:26 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Dave Chinner
2019-08-19 6:34 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Jan Kara
2019-08-19 9:24 ` Dave Chinner
2019-08-19 12:38 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jason Gunthorpe
2019-08-19 21:53 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Ira Weiny
2019-08-20 1:12 ` Dave Chinner
2019-08-20 11:55 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jason Gunthorpe
2019-08-21 18:02 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Ira Weiny
2019-08-21 18:13 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jason Gunthorpe
2019-08-21 18:22 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) John Hubbard
2019-08-21 18:57 ` Ira Weiny
2019-08-21 19:06 ` Ira Weiny
2019-08-21 19:48 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jason Gunthorpe
2019-08-21 20:44 ` Ira Weiny
2019-08-21 23:49 ` Jason Gunthorpe
2019-08-23 3:23 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Dave Chinner
2019-08-23 12:04 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jason Gunthorpe
2019-08-24 0:11 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Dave Chinner
2019-08-24 5:08 ` Ira Weiny
2019-08-26 5:55 ` Dave Chinner
2019-08-29 2:02 ` Ira Weiny
2019-08-29 3:27 ` John Hubbard
2019-08-29 16:16 ` Ira Weiny
2019-09-02 22:26 ` Dave Chinner
2019-09-04 16:54 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Ira Weiny
2019-08-25 19:39 ` Jason Gunthorpe
2019-08-24 4:49 ` Ira Weiny
2019-08-25 19:40 ` Jason Gunthorpe
2019-08-23 0:59 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Dave Chinner
2019-08-23 17:15 ` Ira Weiny
2019-08-24 0:18 ` Dave Chinner
2019-08-20 0:05 ` John Hubbard
2019-08-20 1:20 ` Dave Chinner
2019-08-20 3:09 ` John Hubbard
2019-08-20 3:36 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Dave Chinner
2019-08-21 18:43 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) John Hubbard
2019-08-21 19:09 ` Ira Weiny
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