Re: BUG: unable to handle page fault for address - EIP: __kmap_local_page_prot

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, May 19 2021 at 20:38, Naresh Kamboju wrote:
> While running LTP mm test suite on i386 kernel the following warning and BUG
> reported on linux next 5.13.0-rc2-next-20210519.
>
> The warning is not regression, We have been noticing these warnings often on
> i386

Noticing? Did you report them?

> but kernel BUG: looks to be a new crash.

It's just the consequence of the problem which is pointed out by the
warning. Fix below.

Thanks,

        tglx
---
Subject: x86: Don't enable CONFIG_MOVE_PUD for 32bit and !PAE
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 19 May 2021 20:37:34 +0200

MOVE_PUD cannot work for 2-level paging obviously.

Fixes: be37c98d1134 ("x86: mremap speedup - Enable HAVE_MOVE_PUD")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: stable@vger.kernel.org
---
 arch/x86/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -219,7 +219,7 @@ config X86
 	select HAVE_MIXED_BREAKPOINTS_REGS
 	select HAVE_MOD_ARCH_SPECIFIC
 	select HAVE_MOVE_PMD
-	select HAVE_MOVE_PUD
+	select HAVE_MOVE_PUD			if PGTABLE_LEVELS > 2
 	select HAVE_NMI
 	select HAVE_OPTPROBES
 	select HAVE_PCSPKR_PLATFORM