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SubjectRe: [patch 00/76] 2.6.24-stable review
On Fri, Mar 21, 2008 at 03:42:50PM -0700, Chris Wright wrote:
> This is the start of the stable review cycle for the 2.6.24.4 release.

Hi Chris,
The below is also a candidate for 2.6.24.4. It should apply cleanly.
Joe

Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6d2144d355d2a532e5cc3fc12a6ba2a8d4ef15e4
Commit: 6d2144d355d2a532e5cc3fc12a6ba2a8d4ef15e4
Parent: b6210386787728b84db25adc4f1eba70440a4c73
Author: Joe Korty <joe.korty@ccur.com>
AuthorDate: Wed Mar 5 15:04:59 2008 -0800
Committer: Christoph Lameter <clameter@sgi.com>
CommitDate: Thu Mar 6 16:21:50 2008 -0800

slab: NUMA slab allocator migration bugfix

NUMA slab allocator cpu migration bugfix

The NUMA slab allocator (specifically, cache_alloc_refill)
is not refreshing its local copies of what cpu and what
numa node it is on, when it drops and reacquires the irq
block that it inherited from its caller. As a result
those values become invalid if an attempt to migrate the
process to another numa node occured while the irq block
had been dropped.

The solution is to make cache_alloc_refill reload these
variables whenever it drops and reacquires the irq block.

The error is very difficult to hit. When it does occur,
one gets the following oops + stack traceback bits in
check_spinlock_acquired:

kernel BUG at mm/slab.c:2417
cache_alloc_refill+0xe6
kmem_cache_alloc+0xd0
...

This patch was developed against 2.6.23, ported to and
compiled-tested only against 2.6.25-rc4.

Signed-off-by: Joe Korty <joe.korty@ccur.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
---
mm/slab.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index f7faff7..e6c698f 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2964,11 +2964,10 @@ static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
struct array_cache *ac;
int node;

- node = numa_node_id();
-
+retry:
check_irq_off();
+ node = numa_node_id();
ac = cpu_cache_get(cachep);
-retry:
batchcount = ac->batchcount;
if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
/*


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