From: Jason Gunthorpe <jgg@ziepe.ca>
To: Gal Pressman <galpress@amazon.com>
Cc: aarcange@redhat.com, akpm@linux-foundation.org,
gokhale2@llnl.gov, hch@lst.de, jack@suse.cz, jannh@google.com,
jhubbard@nvidia.com, kirill@shutemov.name, ktkhai@virtuozzo.com,
leonro@nvidia.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, mcfadden8@llnl.gov, oleg@redhat.com,
peterx@redhat.com, torvalds@linux-foundation.org,
wzam@amazon.com, yang.shi@linux.alibaba.com
Subject: Re: [PATCH 1/4] mm: Trial do_wp_page() simplification
Date: Wed, 3 Feb 2021 10:00:15 -0400 [thread overview]
Message-ID: <20210203140015.GP4718@ziepe.ca> (raw)
In-Reply-To: <20210203124358.59017-1-galpress@amazon.com>
On Wed, Feb 03, 2021 at 02:43:58PM +0200, Gal Pressman wrote:
> > On Tue, Feb 02, 2021 at 12:05:36PM -0500, Peter Xu wrote:
> >
> >> > Gal, you could also MADV_DONTFORK this range if you are explicitly
> >> > allocating them via special mmap.
> >>
> >> Yeah I wanted to mention this one too but I just forgot when reply: the issue
> >> thread previously pasted smells like some people would like to drop
> >> MADV_DONTFORK, but if it's able to still be applied I don't know why
> >> not..
> >
> > I want to drop the MADV_DONTFORK for dynamic data memory allocated by
> > the application layers (eg with malloc) without knowledge of how they
> > will be used.
> >
> > This case is a buffer internal to the communication system that we
> > know at allocation time how it will be used; so an explicit,
> > deliberate, MADV_DONTFORK is fine
>
> We are referring to libfabric's bounce buffers, correct?
> Libfabric could be considered as the "app" here, it's not clear why these
> buffers should be DONTFORK'd before ibv_reg_mr() but others don't.
I assumed they were internal to the EFA code itself.
> Anyway, it should be simple enough to madvise them after allocation, although I
> think it's part of libfabric's generic code (which isn't necessarily used on
> top of rdma-core).
Ah, so that is a reasonable justification for wanting to fix this in
the kernel..
Lets give Peter some time first.
The other direction to validate this approach is to remove the
MAP_HUGETLB flags and rely on THP instead, and/or mark them as
MAP_SHARED.
I'm not sure generic code should be use using MAP_HUGETLB..
This would be enough to confirm that everything else is working as
expected
Thanks,
Jason
next prev parent reply other threads:[~2021-02-03 14:02 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 14:40 [PATCH 1/4] mm: Trial do_wp_page() simplification Gal Pressman
2021-02-02 16:31 ` Peter Xu
2021-02-02 16:44 ` Jason Gunthorpe
2021-02-02 17:05 ` Peter Xu
2021-02-02 17:13 ` Jason Gunthorpe
2021-02-03 12:43 ` Gal Pressman
2021-02-03 14:00 ` Jason Gunthorpe [this message]
2021-02-03 14:47 ` Gal Pressman
-- strict thread matches above, loose matches on Subject: below --
2020-08-21 23:49 [PATCH 0/4] mm: Simplfy cow handling Peter Xu
2020-08-21 23:49 ` [PATCH 1/4] mm: Trial do_wp_page() simplification Peter Xu
2020-08-24 8:36 ` Kirill Tkhai
2020-08-24 14:30 ` Jan Kara
2020-08-24 15:37 ` Kirill Tkhai
2020-08-24 18:22 ` Linus Torvalds
2020-08-24 18:22 ` Linus Torvalds
2020-09-01 7:01 ` Hugh Dickins
2020-09-01 7:01 ` Hugh Dickins
2020-09-14 14:38 ` Jason Gunthorpe
2020-09-14 17:32 ` Linus Torvalds
2020-09-14 17:32 ` Linus Torvalds
2020-09-14 18:34 ` Peter Xu
2020-09-14 21:15 ` Peter Xu
2020-09-14 22:55 ` Jason Gunthorpe
2020-09-14 22:59 ` Linus Torvalds
2020-09-14 22:59 ` Linus Torvalds
2020-09-14 23:28 ` Jason Gunthorpe
2020-09-15 0:19 ` Linus Torvalds
2020-09-15 0:19 ` Linus Torvalds
2020-09-15 14:50 ` Peter Xu
2020-09-15 15:17 ` Peter Xu
2020-09-15 16:05 ` Jason Gunthorpe
2020-09-15 18:29 ` Jason Gunthorpe
2020-09-15 19:13 ` Peter Xu
2020-09-15 19:38 ` Jason Gunthorpe
2020-09-15 21:33 ` Peter Xu
2020-09-15 23:22 ` Jason Gunthorpe
2020-09-16 1:50 ` John Hubbard
2020-09-16 17:48 ` Jason Gunthorpe
2020-09-16 18:46 ` Peter Xu
2020-09-17 11:25 ` Jason Gunthorpe
2020-09-17 18:11 ` Linus Torvalds
2020-09-17 18:11 ` Linus Torvalds
2020-09-17 19:38 ` Jason Gunthorpe
2020-09-17 19:51 ` Linus Torvalds
2020-09-17 19:51 ` Linus Torvalds
2020-09-18 16:40 ` Peter Xu
2020-09-18 17:16 ` Linus Torvalds
2020-09-18 17:16 ` Linus Torvalds
2020-09-18 19:57 ` Peter Xu
2020-09-18 17:32 ` Jason Gunthorpe
2020-09-18 20:40 ` Peter Xu
2020-09-18 20:59 ` Linus Torvalds
2020-09-18 20:59 ` Linus Torvalds
2020-09-19 0:28 ` Jason Gunthorpe
2020-09-18 21:06 ` John Hubbard
2020-09-19 0:01 ` Jason Gunthorpe
2020-09-21 8:35 ` Jan Kara
2020-09-21 12:03 ` Jason Gunthorpe
2022-02-16 16:59 ` Oded Gabbay
2022-02-16 17:24 ` Oded Gabbay
2022-02-16 19:04 ` Linus Torvalds
2022-02-16 19:20 ` Oded Gabbay
2022-02-16 19:24 ` David Hildenbrand
2020-09-21 13:42 ` Michal Hocko
2020-09-21 14:18 ` Peter Xu
2020-09-21 14:28 ` Michal Hocko
2020-09-21 14:38 ` Tejun Heo
2020-09-21 14:43 ` Christian Brauner
2020-09-21 14:55 ` Michal Hocko
2020-09-21 15:04 ` Christian Brauner
2020-09-21 16:06 ` Michal Hocko
2020-09-23 7:53 ` Michal Hocko
2020-09-21 14:41 ` Christian Brauner
2020-09-21 14:57 ` Michal Hocko
2020-09-21 16:31 ` Peter Xu
2020-09-17 18:14 ` Peter Xu
2020-09-17 18:26 ` Linus Torvalds
2020-09-17 18:26 ` Linus Torvalds
2020-09-17 19:03 ` Peter Xu
2020-09-17 19:42 ` Linus Torvalds
2020-09-17 19:42 ` Linus Torvalds
2020-09-17 19:55 ` John Hubbard
2020-09-17 20:06 ` Jason Gunthorpe
2020-09-17 20:19 ` John Hubbard
2020-09-17 20:25 ` Jason Gunthorpe
2020-09-17 20:35 ` Linus Torvalds
2020-09-17 20:35 ` Linus Torvalds
2020-09-17 21:40 ` Peter Xu
2020-09-17 22:09 ` Jason Gunthorpe
2020-09-17 22:25 ` Linus Torvalds
2020-09-17 22:25 ` Linus Torvalds
2020-09-17 22:48 ` Ira Weiny
2020-09-18 9:36 ` Jan Kara
2020-09-18 9:44 ` Jan Kara
2020-09-18 16:19 ` Jason Gunthorpe
2020-09-15 10:23 ` Leon Romanovsky
2020-09-15 15:56 ` Jason Gunthorpe
2020-09-15 15:03 ` Oleg Nesterov
2020-09-15 16:18 ` Peter Xu
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