Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-19 Thread Dan Williams
On Thu, Apr 19, 2018 at 3:44 AM, Jan Kara wrote: > On Fri 13-04-18 15:03:51, Dan Williams wrote: >> On Mon, Apr 9, 2018 at 9:51 AM, Dan Williams >> wrote: >> > On Mon, Apr 9, 2018 at 9:49 AM, Jan Kara wrote: >> >> On Sat 07-04-18 12:38:24, Dan Williams wrote: >> > [..] >> >>> I wonder if this c

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-19 Thread Jan Kara
On Fri 13-04-18 15:03:51, Dan Williams wrote: > On Mon, Apr 9, 2018 at 9:51 AM, Dan Williams wrote: > > On Mon, Apr 9, 2018 at 9:49 AM, Jan Kara wrote: > >> On Sat 07-04-18 12:38:24, Dan Williams wrote: > > [..] > >>> I wonder if this can be trivially solved by using srcu. I.e. we don't > >>> nee

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-13 Thread Paul E. McKenney
On Fri, Apr 13, 2018 at 03:03:51PM -0700, Dan Williams wrote: > On Mon, Apr 9, 2018 at 9:51 AM, Dan Williams wrote: > > On Mon, Apr 9, 2018 at 9:49 AM, Jan Kara wrote: > >> On Sat 07-04-18 12:38:24, Dan Williams wrote: > > [..] > >>> I wonder if this can be trivially solved by using srcu. I.e. we

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-13 Thread Dan Williams
On Mon, Apr 9, 2018 at 9:51 AM, Dan Williams wrote: > On Mon, Apr 9, 2018 at 9:49 AM, Jan Kara wrote: >> On Sat 07-04-18 12:38:24, Dan Williams wrote: > [..] >>> I wonder if this can be trivially solved by using srcu. I.e. we don't >>> need to wait for a global quiescent state, just a >>> get_use

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-09 Thread Paul E. McKenney
On Mon, Apr 09, 2018 at 06:39:10PM +0200, Jan Kara wrote: > On Sat 07-04-18 20:11:13, Paul E. McKenney wrote: > > On Sat, Apr 07, 2018 at 12:38:24PM -0700, Dan Williams wrote: > > > [ adding Paul and Josh ] > > > > > > On Wed, Apr 4, 2018 at 2:46 AM, Jan Kara wrote: > > > > On Fri 30-03-18 21:03:

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-09 Thread Dan Williams
On Mon, Apr 9, 2018 at 9:49 AM, Jan Kara wrote: > On Sat 07-04-18 12:38:24, Dan Williams wrote: [..] >> I wonder if this can be trivially solved by using srcu. I.e. we don't >> need to wait for a global quiescent state, just a >> get_user_pages_fast() quiescent state. ...or is that an abuse of the

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-09 Thread Jan Kara
On Sat 07-04-18 12:38:24, Dan Williams wrote: > [ adding Paul and Josh ] > > On Wed, Apr 4, 2018 at 2:46 AM, Jan Kara wrote: > > On Fri 30-03-18 21:03:30, Dan Williams wrote: > >> Background: > >> > >> get_user_pages() in the filesystem pins file backed memory pages for > >> access by devices per

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-09 Thread Jan Kara
On Sat 07-04-18 20:11:13, Paul E. McKenney wrote: > On Sat, Apr 07, 2018 at 12:38:24PM -0700, Dan Williams wrote: > > [ adding Paul and Josh ] > > > > On Wed, Apr 4, 2018 at 2:46 AM, Jan Kara wrote: > > > On Fri 30-03-18 21:03:30, Dan Williams wrote: > > >> Background: > > >> > > >> get_user_page

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-07 Thread Paul E. McKenney
On Sat, Apr 07, 2018 at 12:38:24PM -0700, Dan Williams wrote: > [ adding Paul and Josh ] > > On Wed, Apr 4, 2018 at 2:46 AM, Jan Kara wrote: > > On Fri 30-03-18 21:03:30, Dan Williams wrote: > >> Background: > >> > >> get_user_pages() in the filesystem pins file backed memory pages for > >> acces

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-07 Thread Dan Williams
[ adding Paul and Josh ] On Wed, Apr 4, 2018 at 2:46 AM, Jan Kara wrote: > On Fri 30-03-18 21:03:30, Dan Williams wrote: >> Background: >> >> get_user_pages() in the filesystem pins file backed memory pages for >> access by devices performing dma. However, it only pins the memory pages >> not the

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-04 Thread Dan Williams
On Wed, Apr 4, 2018 at 2:46 AM, Jan Kara wrote: > On Fri 30-03-18 21:03:30, Dan Williams wrote: >> Background: >> >> get_user_pages() in the filesystem pins file backed memory pages for >> access by devices performing dma. However, it only pins the memory pages >> not the page-to-file offset assoc

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-04 Thread Jan Kara
On Wed 04-04-18 11:46:56, Jan Kara wrote: > On Fri 30-03-18 21:03:30, Dan Williams wrote: > > Background: > > > > get_user_pages() in the filesystem pins file backed memory pages for > > access by devices performing dma. However, it only pins the memory pages > > not the page-to-file offset associ

Re: [PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-04-04 Thread Jan Kara
On Fri 30-03-18 21:03:30, Dan Williams wrote: > Background: > > get_user_pages() in the filesystem pins file backed memory pages for > access by devices performing dma. However, it only pins the memory pages > not the page-to-file offset association. If a file is truncated the > pages are mapped o

[PATCH v8 15/18] mm, fs, dax: handle layout changes to pinned dax mappings

2018-03-30 Thread Dan Williams
Background: get_user_pages() in the filesystem pins file backed memory pages for access by devices performing dma. However, it only pins the memory pages not the page-to-file offset association. If a file is truncated the pages are mapped out of the file and dma may continue indefinitely into a pa