lkml.org 
[lkml]   [2019]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: "reuse mergeable anon_vma as parent when fork" causes a crash on s390
On Thu, Oct 10, 2019 at 10:36:01AM +0800, Wei Yang wrote:
>Hi, Qian, Shakeel
>
>Thanks for testing.
>
>Sounds I missed some case to handle. anon_vma_clone() now would be called in
>vma_adjust, which is a different case when it is introduced.
>

Well, I have to correct my statement. The reason is we may did something more
in anon_vma_clone().

Here is a quick fix, while I need to go through all the cases carefully.

diff --git a/mm/rmap.c b/mm/rmap.c
index 12f6c3d7fd9d..2844f442208d 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -271,7 +271,7 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
* 1. Parent has vm_prev, which implies we have vm_prev.
* 2. Parent and its vm_prev have the same anon_vma.
*/
- if (pprev && pprev->anon_vma == src->anon_vma)
+ if (!dst->anon_vma && pprev && pprev->anon_vma == src->anon_vma)
dst->anon_vma = prev->anon_vma;

list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
>BTW, do you have the specific test case? So that I could verify my change. The
>kernel build test doesn't trigger this.
>
>Thanks a lot :-)
>
>On Wed, Oct 09, 2019 at 03:21:11PM -0700, Shakeel Butt wrote:
>--
>Wei Yang
>Help you, Help me

--
Wei Yang
Help you, Help me

\
 
 \ /
  Last update: 2019-10-10 05:16    [W:0.039 / U:0.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site