Hi Hugh,
On Tue, Dec 01, 2020 at 01:31:21PM -0800, Hugh Dickins wrote:
> Please don't ever rely on that i_private business for correctness: as
The out of order and lockless "if (inode->i_private)" branch didn't
inspire much confidence in terms of being able to rely on it for
locking correctness i
On Sat, 28 Nov 2020, Peter Xu wrote:
> On Fri, Nov 27, 2020 at 07:33:39PM -0500, Andrea Arcangeli wrote:
>
> > Now it would be ok if filemap_map_pages re-filled the ptes, after they
> > were zapped the first time by fallocate, and then the fallocate would
> > zap them again before truncating the p
Hi Peter,
On Sat, Nov 28, 2020 at 10:29:03AM -0500, Peter Xu wrote:
> Yes. A trivial supplementary detail is that filemap_map_pages() will only set
> it read-only since alloc_set_pte() will only set write bit if it's a write.
> In
> our case it's read fault-around so without it. However it'll
On Fri, Nov 27, 2020 at 07:33:39PM -0500, Andrea Arcangeli wrote:
> Hello,
Hi, Andrea!
>
> On Fri, Nov 27, 2020 at 12:22:24PM +, Matthew Wilcox wrote:
> > On Thu, Nov 26, 2020 at 05:23:59PM -0500, Peter Xu wrote:
> > > For wr-protected mode uffds, errornously fault in those pages around
> >
Hello,
On Fri, Nov 27, 2020 at 12:22:24PM +, Matthew Wilcox wrote:
> On Thu, Nov 26, 2020 at 05:23:59PM -0500, Peter Xu wrote:
> > For wr-protected mode uffds, errornously fault in those pages around could
> > lead
> > to threads accessing the pages without uffd server's awareness. For
> >
On Fri, Nov 27, 2020 at 06:00:44PM +0100, David Hildenbrand wrote:
> On 26.11.20 23:23, Peter Xu wrote:
> > Faulting around for reads are in most cases helpful for the performance so
> > that
> > continuous memory accesses may avoid another trip of page fault. However it
> > may not always work a
On 26.11.20 23:23, Peter Xu wrote:
> Faulting around for reads are in most cases helpful for the performance so
> that
> continuous memory accesses may avoid another trip of page fault. However it
> may not always work as expected.
>
> For example, userfaultfd registered regions may not be the b
Matthew,
Thanks for the review comments.
On Fri, Nov 27, 2020 at 12:22:24PM +, Matthew Wilcox wrote:
> On Thu, Nov 26, 2020 at 05:23:59PM -0500, Peter Xu wrote:
> > For missing mode uffds, fault around does not help because if the page cache
> > existed, then the page should be there already.
On Fri, Nov 27, 2020 at 10:16:05AM +0200, Mike Rapoport wrote:
> On Thu, Nov 26, 2020 at 05:23:59PM -0500, Peter Xu wrote:
> > Faulting around for reads are in most cases helpful for the performance so
> > that
> > continuous memory accesses may avoid another trip of page fault. However it
> > ma
On Thu, Nov 26, 2020 at 05:23:59PM -0500, Peter Xu wrote:
> For missing mode uffds, fault around does not help because if the page cache
> existed, then the page should be there already. If the page cache is not
> there, nothing else we can do, either. If the fault-around code is destined
> to
>
On Thu, Nov 26, 2020 at 05:23:59PM -0500, Peter Xu wrote:
> Faulting around for reads are in most cases helpful for the performance so
> that
> continuous memory accesses may avoid another trip of page fault. However it
> may not always work as expected.
>
> For example, userfaultfd registered r
Faulting around for reads are in most cases helpful for the performance so that
continuous memory accesses may avoid another trip of page fault. However it
may not always work as expected.
For example, userfaultfd registered regions may not be the best candidate for
pre-faults around the reads.
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