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Subject[PATCH] mm/slab.c: add node spinlock protect in __cache_free_alien
Date
From: Zhang Qiang <qiang.zhang@windriver.com>

We should add node spinlock protect "n->alien" which may be
assigned to NULL in cpuup_canceled func. cause address access
exception.

Fixes: 18bf854117c6 ("slab: use get_node() and kmem_cache_node() functions")
Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com>
---
mm/slab.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index a89633603b2d..290523c90b4e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -759,8 +759,10 @@ static int __cache_free_alien(struct kmem_cache *cachep, void *objp,

n = get_node(cachep, node);
STATS_INC_NODEFREES(cachep);
+ spin_lock(&n->list_lock);
if (n->alien && n->alien[page_node]) {
alien = n->alien[page_node];
+ spin_unlock(&n->list_lock);
ac = &alien->ac;
spin_lock(&alien->lock);
if (unlikely(ac->avail == ac->limit)) {
@@ -769,14 +771,15 @@ static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
}
ac->entry[ac->avail++] = objp;
spin_unlock(&alien->lock);
- slabs_destroy(cachep, &list);
} else {
+ spin_unlock(&n->list_lock);
n = get_node(cachep, page_node);
spin_lock(&n->list_lock);
free_block(cachep, &objp, 1, page_node, &list);
spin_unlock(&n->list_lock);
- slabs_destroy(cachep, &list);
}
+
+ slabs_destroy(cachep, &list);
return 1;
}

--
2.26.2
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