lkml.org 
[lkml]   [2009]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: [BUG] set_mempolicy(MPOL_INTERLEAV) cause kernel panic
From
KAMEZAWA Hiroyuki wrote:
> Andrew Morton wrote:
>> On Fri, 24 Jul 2009 15:51:51 -0700 (PDT)
>> David Rientjes <rientjes@google.com> wrote:
>
>> afaik we don't have a final patch for this. I asked Motohiro-san about
>> this and he's proposing that we revert the offending change (which one
>> was it?) if nothing gets fixed soon - the original author is on a
>> lengthy vacation.
>>
>>
>> If we _do_ have a patch then can we start again? Someone send out the
>> patch
>> and let's take a look at it.
> Hmm, like this ? (cleaned up David's one because we shouldn't have
> extra nodemask_t on stack.)
>
> Problems are
> - rebind() is maybe broken but no good idea.
> (but it seems to be broken in old kernels
> - Who can test this is only a user who has possible node on SRAT.
>

> + /* should we call is_valid_nodemask() here ?*/
> if (pol->flags & MPOL_F_RELATIVE_NODES)
> mpol_relative_nodemask(&cpuset_context_nmask, nodes,
> - &cpuset_current_mems_allowed);
> + &cpuset_context_nmask);
Sorry this part is buggy.

But to fix this, we use extra nodemask here and this patch will
allocate 3 nodemasks on stack!
Then, here is a much easier fix. for trusting cpuset more.

==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

task->mems_allowed is guaranteed to be only includes valid nodes when
it is set under cpuset. but, at init, all possible nodes are included.
fix it.

And at cpuset-rebind, caluculated result can be a invaild one.
In that case, trust cpuset's one

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
init/main.c | 4 ++--
mm/mempolicy.c | 7 ++++++-
2 files changed, 8 insertions(+), 3 deletions(-)

Index: mmotm-2.6.31-Jul16/init/main.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/init/main.c
+++ mmotm-2.6.31-Jul16/init/main.c
@@ -855,9 +855,9 @@ static int __init kernel_init(void * unu
lock_kernel();

/*
- * init can allocate pages on any node
+ * init can allocate pages on any online node
*/
- set_mems_allowed(node_possible_map);
+ set_mems_allowed(node_state[N_HIGH_MEMORY]);
/*
* init can run on any cpu.
*/
Index: mmotm-2.6.31-Jul16/mm/mempolicy.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/mm/mempolicy.c
+++ mmotm-2.6.31-Jul16/mm/mempolicy.c
@@ -290,7 +290,12 @@ static void mpol_rebind_nodemask(struct
*nodes);
pol->w.cpuset_mems_allowed = *nodes;
}
-
+ /*
+ * tmp can be invalid ...just use cpuset's one in that case.
+ */
+ if (nodes_empty(tmp) ||
+ ((pol->mode == MPOL_BIND) && !is_valid_nodemask(&tmp)))
+ tmp = *nodes;
pol->v.nodes = tmp;
if (!node_isset(current->il_next, tmp)) {
current->il_next = next_node(current->il_next, tmp);






\
 
 \ /
  Last update: 2009-07-25 04:39    [W:0.111 / U:6.768 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site