Re: WARNING: at mm/mremap.c:211 move_page_tables in i386

Naresh Kamboju
2020-07-11T17:27:55Z

On Sat, 11 Jul 2020 at 01:35, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Fri, Jul 10, 2020 at 10:48 AM Naresh Kamboju
> <naresh.kamboju@linaro.org> wrote:

I have started bisecting this problem and found the first bad commit

commit 9f132f7e145506efc0744426cb338b18a54afc3b
Author: Joel Fernandes (Google) <joel@joelfernandes.org>
Date: Thu Jan 3 15:28:41 2019 -0800

mm: select HAVE_MOVE_PMD on x86 for faster mremap

Moving page-tables at the PMD-level on x86 is known to be safe. Enable
this option so that we can do fast mremap when possible.

Link: http://lkml.kernel.org/r/20181108181201.88826-4-joelaf@google.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Suggested-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e260460210e1..6185d4f33296 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -172,6 +172,7 @@ config X86
select HAVE_MEMBLOCK_NODE_MAP
select HAVE_MIXED_BREAKPOINTS_REGS
select HAVE_MOD_ARCH_SPECIFIC
+ select HAVE_MOVE_PMD
select HAVE_NMI
select HAVE_OPROFILE
select HAVE_OPTPROBES

After reverting the above patch the reported kernel warning got fixed on
Linus mainline tree 5.8.0-rc4.

--
Linaro LKFT