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>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

diff --git a/mm/Kconfig b/mm/Kconfig
index 40a9bfcd5062e1d06313125bdec31d7c4f403553..5dc28e9205e00fcdce1c55479b1bd29e5fffd803 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -744,7 +744,7 @@ 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