+ mm-mark-idle-page-tracking-as-broken.patch added to -mm tree

+ mm-mark-idle-page-tracking-as-broken.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm: mark idle page tracking as BROKEN
has been added to the -mm tree.  Its filename is
     mm-mark-idle-page-tracking-as-broken.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-mark-idle-page-tracking-as-broken.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-mark-idle-page-tracking-as-broken.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm: mark idle page tracking as BROKEN

In discussion with other MM developers around how idle page tracking
should be fixed for transparent huge pages, several expressed the opinion
that it should be removed as it is inefficient at accomplishing the job
that it is supposed to, and we have better mechanisms (eg uffd) for
accomplishing the same goals these days.

Mark the feature as BROKEN for now and we can remove it entirely in a few
months if nobody complains.  It is not enabled by Android, ChromeOS,
Debian, Fedora or SUSE.  Red Hat enabled it with RHEL-8.1 and UEK followed
suit, but I have been unable to find why RHEL enabled it.

Link: https://lkml.kernel.org/r/20210612000714.775825-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Yu Zhao <yuzhao@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
SeongJae Park <sj38.park@gmail.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/Kconfig~mm-mark-idle-page-tracking-as-broken
+++ a/mm/Kconfig
@@ -772,7 +772,7 @@ config DEFERRED_STRUCT_PAGE_INIT
 
 config IDLE_PAGE_TRACKING
 	bool "Enable idle page tracking"
-	depends on SYSFS && MMU
+	depends on SYSFS && MMU && BROKEN
 	select PAGE_EXTENSION if !64BIT
 	help
 	  This feature allows to estimate the amount of user pages that have
_

Patches currently in -mm which might be from willy@infradead.org are

mm-mark-idle-page-tracking-as-broken.patch
mm-make-__dump_page-static.patch
mm-debug-factor-pagepoisoned-out-of-__dump_page.patch
mm-page_owner-constify-dump_page_owner.patch
mm-make-compound_head-const-preserving.patch
mm-constify-get_pfnblock_flags_mask-and-get_pfnblock_migratetype.patch
mm-constify-page_count-and-page_ref_count.patch
mm-optimise-nth_page-for-contiguous-memmap.patch

Re: + mm-mark-idle-page-tracking-as-broken.patch added to -mm tree

[Rafael Aquini]

On Mon, Jun 14, 2021 at 07:05:47PM -0700, akpm@linux-foundation.org wrote:
> 
> The patch titled
>      Subject: mm: mark idle page tracking as BROKEN
> has been added to the -mm tree.  Its filename is
>      mm-mark-idle-page-tracking-as-broken.patch
> 
> This patch should soon appear at
>     https://ozlabs.org/~akpm/mmots/broken-out/mm-mark-idle-page-tracking-as-broken.patch
> and later at
>     https://ozlabs.org/~akpm/mmotm/broken-out/mm-mark-idle-page-tracking-as-broken.patch
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> 
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
> 
> ------------------------------------------------------
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> Subject: mm: mark idle page tracking as BROKEN
> 
> In discussion with other MM developers around how idle page tracking
> should be fixed for transparent huge pages, several expressed the opinion
> that it should be removed as it is inefficient at accomplishing the job
> that it is supposed to, and we have better mechanisms (eg uffd) for
> accomplishing the same goals these days.

I didn't follow the aforementioned discussion, so it would be nice to
have a little bit more detailed explanation on both points raised here
(issues with THP and innefficiency). There are some Red Hat customers
and partners that do rely on the feature, thus the interest. Thanks.

> Mark the feature as BROKEN for now and we can remove it entirely in a few
> months if nobody complains.  It is not enabled by Android, ChromeOS,
> Debian, Fedora or SUSE.  Red Hat enabled it with RHEL-8.1 and UEK followed
> suit, but I have been unable to find why RHEL enabled it.

minor nit on the RHEL mention: CONFIG_IDLE_PAGE_TRACKING is enabled since 8.0
for RHEL-8, and 7.7 for RHEL-7.

Cheers,
-- Rafael

Re: + mm-mark-idle-page-tracking-as-broken.patch added to -mm tree

[Matthew Wilcox]

On Wed, Jun 16, 2021 at 06:29:19PM -0400, Rafael Aquini wrote:
> > In discussion with other MM developers around how idle page tracking
> > should be fixed for transparent huge pages, several expressed the opinion
> > that it should be removed as it is inefficient at accomplishing the job
> > that it is supposed to, and we have better mechanisms (eg uffd) for
> > accomplishing the same goals these days.
> 
> I didn't follow the aforementioned discussion, so it would be nice to
> have a little bit more detailed explanation on both points raised here
> (issues with THP and innefficiency). There are some Red Hat customers
> and partners that do rely on the feature, thus the interest. Thanks.

It would be nice if you asked this on the original thread (which you're
cc'd on) instead of starting a new thread.

> > Mark the feature as BROKEN for now and we can remove it entirely in a few
> > months if nobody complains.  It is not enabled by Android, ChromeOS,
> > Debian, Fedora or SUSE.  Red Hat enabled it with RHEL-8.1 and UEK followed
> > suit, but I have been unable to find why RHEL enabled it.
> 
> minor nit on the RHEL mention: CONFIG_IDLE_PAGE_TRACKING is enabled since 8.0
> for RHEL-8, and 7.7 for RHEL-7.

Red Hat makes it incredibly hard to find out what changed when.
You can't then whine about us not understanding what you're doing,
when you're going out of your way to obfuscate what you do.

Re: + mm-mark-idle-page-tracking-as-broken.patch added to -mm tree

[Rafael Aquini]

On Thu, Jun 17, 2021 at 04:37:17PM +0100, Matthew Wilcox wrote:
> On Wed, Jun 16, 2021 at 06:29:19PM -0400, Rafael Aquini wrote:
> > > In discussion with other MM developers around how idle page tracking
> > > should be fixed for transparent huge pages, several expressed the opinion
> > > that it should be removed as it is inefficient at accomplishing the job
> > > that it is supposed to, and we have better mechanisms (eg uffd) for
> > > accomplishing the same goals these days.
> > 
> > I didn't follow the aforementioned discussion, so it would be nice to
> > have a little bit more detailed explanation on both points raised here
> > (issues with THP and innefficiency). There are some Red Hat customers
> > and partners that do rely on the feature, thus the interest. Thanks.
> 
> It would be nice if you asked this on the original thread (which you're
> cc'd on) instead of starting a new thread.

Sorry about that, but for some weird reason only Andrew's email made its way
into my inbox.



> > > Mark the feature as BROKEN for now and we can remove it entirely in a few
> > > months if nobody complains.  It is not enabled by Android, ChromeOS,
> > > Debian, Fedora or SUSE.  Red Hat enabled it with RHEL-8.1 and UEK followed
> > > suit, but I have been unable to find why RHEL enabled it.
> > 
> > minor nit on the RHEL mention: CONFIG_IDLE_PAGE_TRACKING is enabled since 8.0
> > for RHEL-8, and 7.7 for RHEL-7.
> 
> Red Hat makes it incredibly hard to find out what changed when.
> You can't then whine about us not understanding what you're doing,
> when you're going out of your way to obfuscate what you do.
>

Not whining about it, just pointing out the fixup. That's part
of the review process, isn't it? There's no need to whine back at it.

Re: + mm-mark-idle-page-tracking-as-broken.patch added to -mm tree

[Matthew Wilcox]

On Thu, Jun 17, 2021 at 11:54:31AM -0400, Rafael Aquini wrote:
> On Thu, Jun 17, 2021 at 04:37:17PM +0100, Matthew Wilcox wrote:
> > On Wed, Jun 16, 2021 at 06:29:19PM -0400, Rafael Aquini wrote:
> > > > In discussion with other MM developers around how idle page tracking
> > > > should be fixed for transparent huge pages, several expressed the opinion
> > > > that it should be removed as it is inefficient at accomplishing the job
> > > > that it is supposed to, and we have better mechanisms (eg uffd) for
> > > > accomplishing the same goals these days.
> > > 
> > > I didn't follow the aforementioned discussion, so it would be nice to
> > > have a little bit more detailed explanation on both points raised here
> > > (issues with THP and innefficiency). There are some Red Hat customers
> > > and partners that do rely on the feature, thus the interest. Thanks.
> > 
> > It would be nice if you asked this on the original thread (which you're
> > cc'd on) instead of starting a new thread.
> 
> Sorry about that, but for some weird reason only Andrew's email made its way
> into my inbox.

You should probably file a bug with your IT department then.  There are
a dozen emails cc'ing you in this thread, some from people in your own
company:
https://lore.kernel.org/linux-mm/20210612000714.775825-1-willy@infradead.org/