diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h index 0fe96f3ab3ef..65c732d440d2 100644 --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -55,6 +55,7 @@ struct mempolicy { nodemask_t cpuset_mems_allowed; /* relative to these nodes */ nodemask_t user_nodemask; /* nodemask passed by user */ } w; + struct rcu_head rcu; }; /* diff --git a/kernel/futex/core.c b/kernel/futex/core.c index cf7e610eac42..31e83a09789e 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -342,7 +342,7 @@ static int __futex_key_to_node(struct mm_struct *mm, unsigned long addr) if (!vma) return FUTEX_NO_NODE; - mpol = vma_policy(vma); + mpol = READ_ONCE(vma->vm_policy); if (!mpol) return FUTEX_NO_NODE; diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 0e5175f1c767..cf92bd6a8226 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -487,7 +487,13 @@ void __mpol_put(struct mempolicy *pol) { if (!atomic_dec_and_test(&pol->refcnt)) return; - kmem_cache_free(policy_cache, pol); + /* + * Required to allow mmap_lock_speculative*() access, see for example + * futex_key_to_node_opt(). All accesses are serialized by mmap_lock, + * however the speculative lock section unbound by the normal lock + * boundaries, requiring RCU freeing. + */ + kfree_rcu(pol, rcu); } EXPORT_SYMBOL_FOR_MODULES(__mpol_put, "kvm"); @@ -1020,7 +1026,7 @@ static int vma_replace_policy(struct vm_area_struct *vma, } old = vma->vm_policy; - vma->vm_policy = new; /* protected by mmap_lock */ + WRITE_ONCE(vma->vm_policy, new); /* protected by mmap_lock */ mpol_put(old); return 0;