slab/mempolicy: always use local policy from interrupt context
slab_node() could access current->mempolicy from interrupt context. However there's a race condition during exit where the mempolicy is first freed and then the pointer zeroed. Using this from interrupts seems bogus anyways. The interrupt will interrupt a random process and therefore get a random mempolicy. Many times, this will be idle's, which noone can change. Just disable this here and always use local for slab from interrupts. I also cleaned up the callers of slab_node a bit which always passed the same argument. I believe the original mempolicy code did that in fact, so it's likely a regression. v2: send version with correct logic v3: simplify. fix typo. Reported-by: Arun Sharma <asharma@fb.com> Cc: penberg@kernel.org Cc: cl@linux.com Signed-off-by: Andi Kleen <ak@linux.intel.com> [tdmackey@twitter.com: Rework control flow based on feedback from cl@linux.com, fix logic, and cleanup current task_struct reference] Acked-by: David Rientjes <rientjes@google.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: David Mackey <tdmackey@twitter.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
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@ -215,7 +215,7 @@ extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
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extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
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extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
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extern bool mempolicy_nodemask_intersects(struct task_struct *tsk,
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extern bool mempolicy_nodemask_intersects(struct task_struct *tsk,
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const nodemask_t *mask);
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const nodemask_t *mask);
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extern unsigned slab_node(struct mempolicy *policy);
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extern unsigned slab_node(void);
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extern enum zone_type policy_zone;
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extern enum zone_type policy_zone;
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@ -1602,8 +1602,14 @@ static unsigned interleave_nodes(struct mempolicy *policy)
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* task can change it's policy. The system default policy requires no
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* task can change it's policy. The system default policy requires no
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* such protection.
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* such protection.
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*/
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*/
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unsigned slab_node(struct mempolicy *policy)
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unsigned slab_node(void)
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{
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{
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struct mempolicy *policy;
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if (in_interrupt())
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return numa_node_id();
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policy = current->mempolicy;
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if (!policy || policy->flags & MPOL_F_LOCAL)
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if (!policy || policy->flags & MPOL_F_LOCAL)
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return numa_node_id();
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return numa_node_id();
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@ -3310,7 +3310,7 @@ static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
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if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
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if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
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nid_alloc = cpuset_slab_spread_node();
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nid_alloc = cpuset_slab_spread_node();
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else if (current->mempolicy)
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else if (current->mempolicy)
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nid_alloc = slab_node(current->mempolicy);
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nid_alloc = slab_node();
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if (nid_alloc != nid_here)
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if (nid_alloc != nid_here)
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return ____cache_alloc_node(cachep, flags, nid_alloc);
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return ____cache_alloc_node(cachep, flags, nid_alloc);
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return NULL;
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return NULL;
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@ -3342,7 +3342,7 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
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retry_cpuset:
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retry_cpuset:
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cpuset_mems_cookie = get_mems_allowed();
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cpuset_mems_cookie = get_mems_allowed();
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zonelist = node_zonelist(slab_node(current->mempolicy), flags);
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zonelist = node_zonelist(slab_node(), flags);
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retry:
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retry:
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/*
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/*
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@ -1617,7 +1617,7 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t flags,
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do {
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do {
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cpuset_mems_cookie = get_mems_allowed();
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cpuset_mems_cookie = get_mems_allowed();
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zonelist = node_zonelist(slab_node(current->mempolicy), flags);
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zonelist = node_zonelist(slab_node(), flags);
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for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
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for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
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struct kmem_cache_node *n;
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struct kmem_cache_node *n;
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