lkml.org 
[lkml]   [2020]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: i386: selftests: vm: compaction_test: BUG: kernel NULL pointer dereference, address: 00000000
On Mon, 13 Apr 2020 at 03:12, Peter Xu <peterx@redhat.com> wrote:
> And since this one is very easy to reproduce, I finally noticed that
> we have wrongly enabled uffd-wp on x86_32, which is definely not going
> to work... Because we'll use bit 2 of swap entry assuming that's the
> uffd-wp bit, while that's part of swp offset on 32bit systems.
>
> Naresh, could you try whether below change fixes the issue for you?
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 8d078642b4be..7ac524d1316e 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -149,7 +149,7 @@ config X86
> select HAVE_ARCH_TRACEHOOK
> select HAVE_ARCH_TRANSPARENT_HUGEPAGE
> select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
> - select HAVE_ARCH_USERFAULTFD_WP if USERFAULTFD
> + select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
> select HAVE_ARCH_VMAP_STACK if X86_64
> select HAVE_ARCH_WITHIN_STACK_FRAMES
> select HAVE_ASM_MODVERSIONS
>

Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>

The above patch tested and did not notice the crash.
+ cd /opt/kselftests/default-in-kernel/vm/
+ ./compaction_test
No of huge pages allocated = 297
+ ./compaction_test
[ 46.059785] kauditd_printk_skb: 15 callbacks suppressed
[ 46.059786] audit: type=1334 audit(1586776582.927:25): prog-id=17 op=UNLOAD
[ 46.071997] audit: type=1334 audit(1586776582.927:26): prog-id=16 op=UNLOAD
No of huge pages allocated = 160

Full test log,
https://lkft.validation.linaro.org/scheduler/job/1362495#L1308

Build artifacts.
https://builds.tuxbuild.com/w0ol7cCsGan0wzPp7bNqkg/

- Naresh

\
 
 \ /
  Last update: 2020-04-13 13:31    [W:0.068 / U:0.236 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site