On Wed, 25 Jan 2012, Roland Dreier wrote:
> From: Roland Dreier
>
> Right now, we always pass write==1 to get_user_pages(), even when we
> only intend to read the memory. We pass force==1 if we're going for
> read-only and force==0 if we want writable. The reasoning behind this
> seems to be co
On Thu, 26 Jan 2012, Roland Dreier wrote:
>
> Thanks for the thoughtful answer...
But I should have paid more attention to reading what you had written.
In particular to:
> > > This patch comes from me trying to do userspace RDMA on a memory
> > > region exported from a character driver and mapp
On Fri, 27 Jan 2012, Roland Dreier wrote:
> > Sigh, what a mess ... it seems what we really want to do is know
> > if userspace might trigger a COW because or not, and only do a
> > preemptive COW in that case. (We're not really concerned with
> > userspace fork()ing and setting up a COW in the f
On Mon, 30 Jan 2012, Roland Dreier wrote:
> On Fri, Jan 27, 2012 at 6:19 PM, Hugh Dickins wrote:
> >> > > This patch comes from me trying to do userspace RDMA on a memory
> >> > > region exported from a character driver and mapped with
> >> > &
On Mon, 6 Feb 2012, Roland Dreier wrote:
> Sorry for the slow reply, I got caught in other business...
Negative problem!
>
> On Mon, Jan 30, 2012 at 12:34 PM, Hugh Dickins wrote:
> > The hardest part about implementing that is deciding what snappy
> > name to give the
On Tue, 7 Feb 2012, Hugh Dickins wrote:
> On Mon, 6 Feb 2012, Roland Dreier wrote:
> > Which I think explains why the code is the way it is. But clearly
> > we could do better if we had a better way of telling GUP our real
> > intentions -- ie the FOLL_READONLY_COW flag.
>
On Thu, 9 Feb 2012, Roland Dreier wrote:
> On Wed, Feb 8, 2012 at 3:10 PM, Hugh Dickins wrote:
> > A doubt assaulted me overnight: sorry, I'm back to not understanding.
> >
> > What are these access flags passed into ibv_reg_mr() that are enforced?
> > What relati
he same:
I'd be more likely to screw up NOMMU than make an improvement there.
Suggested-by: Linus Torvalds
Signed-off-by: Hugh Dickins
---
You suggested something like this in the LKML discussion of 887843961c4b
and "bad rss-counter message in 3.14rc5" on March 18th, and I agre
On Fri, 4 Apr 2014, Kirill A. Shutemov wrote:
>
> There's comment in do_wp_page() which is not true anymore with patch
> applied. It should be fixed.
The * Only catch write-faults on shared writable pages,
* read-only shared pages can get COWed by
* get_user_pages(.write=1, .force=1).
Ye
hat should I write in the
> changelog.
Thanks a lot for considering similar issues in uprobes, Oleg: I merely
checked that its uses of get_user_pages() would not be problematic,
and didn't look around to rediscover the worrying mm business that
goes on down there in kernel/events.
>
On Fri, 25 Apr 2014, Oleg Nesterov wrote:
>
> And I forgot to mention, there is another reason why I would like to
> change uprobes to follow the same convention. I still think it would
> be better to kill __replace_page() and use gup(FOLL_WRITE | FORCE)
> in uprobe_write_opcode().
Oh, please ple
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