n Mon, Jun 29, 2009 at 01:50:38PM +0200, Heiko Carstens wrote:
> On Mon, Jun 29, 2009 at 12:39:43PM +0200, Nick Piggin wrote:
> > On Mon, Jun 29, 2009 at 12:31:23PM +0200, Heiko Carstens wrote:
> > > On Mon, Jun 29, 2009 at 03:14:40PM +0530, Sachin Sant wrote:
> > > > I still have problems booting next with SLQB on a s390 box.
> > > >
> > > > Write protected kernel read-only data: 0x12000 - 0x446fff
> > > > Experimental hierarchical RCU implementation.
> > > > Experimental hierarchical RCU init done.
> > > > console ÝttyS0¨ enabled
> > > > Unable to handle kernel pointer dereference at virtual kernel address (null)
> >
> > This could I suppose be due to failed allocation where the caller
> > isn't expecting failure (or using SLAB_PANIC).
> >
> > Did you manage to test with the prink debugging patch for SLQB that
> > I sent for the power6 boot failure? I don't think I saw a reply from
> > you but maybe I missed it?
>
> Could you send me the debug patch as well? I can give it a quick run as well.
This is what I had. It is only helpful for the power6
failure where there was a problem in an allocation from
kmem_cache_create.
---
mm/slqb.c | 40 ++++++++++++++++++++++++++++++++++------
1 file changed, 34 insertions(+), 6 deletions(-)
Index: linux-2.6/mm/slqb.c
===================================================================
--- linux-2.6.orig/mm/slqb.c
+++ linux-2.6/mm/slqb.c
@@ -1456,7 +1456,7 @@ static void *__remote_slab_alloc_node(st
}
static noinline void *__remote_slab_alloc(struct kmem_cache *s,
- gfp_t gfpflags, int node)
+ gfp_t gfpflags, int node, int trace)
{
void *object;
struct zonelist *zonelist;
@@ -1465,19 +1465,32 @@ static noinline void *__remote_slab_allo
enum zone_type high_zoneidx = gfp_zone(gfpflags);
object = __remote_slab_alloc_node(s, gfpflags, node);
+ if (trace && !object)
+ printk("__remote_slab_alloc_node(node:%d) failed\n", node);
if (likely(object || (gfpflags & __GFP_THISNODE)))
return object;
- zonelist = node_zonelist(slab_node(current->mempolicy), gfpflags);
+ node = slab_node(current->mempolicy);
+ if (trace)
+ printk("slab_node(current->mempolicy) = %d\n", node);
+
+ zonelist = node_zonelist(node, gfpflags);
for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
- if (!cpuset_zone_allowed_hardwall(zone, gfpflags))
+ if (!cpuset_zone_allowed_hardwall(zone, gfpflags)) {
+ if (trace)
+ printk("cpuset not allowed node:%d\n", zone_to_nid(zone));
continue;
+ }
node = zone_to_nid(zone);
object = __remote_slab_alloc_node(s, gfpflags, node);
if (likely(object))
return object;
+ if (trace)
+ printk("__remote_slab_alloc_node(node:%d) failed\n", node);
}
+ if (trace)
+ printk("__remote_slab_alloc failed\n");
return NULL;
}
#endif
@@ -1488,7 +1501,7 @@ static noinline void *__remote_slab_allo
* Must be called with interrupts disabled.
*/
static __always_inline void *__slab_alloc(struct kmem_cache *s,
- gfp_t gfpflags, int node)
+ gfp_t gfpflags, int node, int trace)
{
void *object;
struct kmem_cache_cpu *c;
@@ -1497,7 +1510,7 @@ static __always_inline void *__slab_allo
#ifdef CONFIG_NUMA
if (unlikely(node != -1) && unlikely(node != numa_node_id())) {
try_remote:
- return __remote_slab_alloc(s, gfpflags, node);
+ return __remote_slab_alloc(s, gfpflags, node, trace);
}
#endif
@@ -1509,6 +1522,8 @@ try_remote:
object = cache_list_get_page(s, l);
if (unlikely(!object)) {
object = __slab_alloc_page(s, gfpflags, node);
+ if (trace && !object)
+ printk("__slab_alloc_page(node:%d) failed\n", node);
#ifdef CONFIG_NUMA
if (unlikely(!object)) {
node = numa_node_id();
@@ -1532,10 +1547,11 @@ static __always_inline void *slab_alloc(
{
void *object;
unsigned long flags;
+ int trace = 0;
again:
local_irq_save(flags);
- object = __slab_alloc(s, gfpflags, node);
+ object = __slab_alloc(s, gfpflags, node, trace);
local_irq_restore(flags);
if (unlikely(slab_debug(s)) && likely(object)) {
@@ -1546,6 +1562,18 @@ again:
if (unlikely(gfpflags & __GFP_ZERO) && likely(object))
memset(object, 0, s->objsize);
+ if (!object && !trace) {
+ trace = 1;
+ dump_stack();
+ printk("slab_alloc allocation failed\n");
+ printk("slab:%s flags:%x node:%d\n", s->name, gfpflags, node);
+ goto again;
+ }
+ if (trace) {
+ if (object)
+ printk("slab_alloc allocation worked when being traced, bugger\n");
+ }
+
return object;
}
--
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