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SLAB: Fix lockdep annotations for CPU hotplug
As reported by Paul McKenney: I am seeing some lockdep complaints in rcutorture runs that include frequent CPU-hotplug operations. The tests are otherwise successful. My first thought was to send a patch that gave each array_cache structure's ->lock field its own struct lock_class_key, but you already have a init_lock_keys() that seems to be intended to deal with this. ------------------------------------------------------------------------ ============================================= [ INFO: possible recursive locking detected ] 2.6.32-rc4-autokern1 #1 --------------------------------------------- syslogd/2908 is trying to acquire lock: (&nc->lock){..-...}, at: [<c0000000001407f4>] .kmem_cache_free+0x118/0x2d4 but task is already holding lock: (&nc->lock){..-...}, at: [<c0000000001411bc>] .kfree+0x1f0/0x324 other info that might help us debug this: 3 locks held by syslogd/2908: #0: (&u->readlock){+.+.+.}, at: [<c0000000004556f8>] .unix_dgram_recvmsg+0x70/0x338 #1: (&nc->lock){..-...}, at: [<c0000000001411bc>] .kfree+0x1f0/0x324 #2: (&parent->list_lock){-.-...}, at: [<c000000000140f64>] .__drain_alien_cache+0x50/0xb8 stack backtrace: Call Trace: [c0000000e8ccafc0] [c0000000000101e4] .show_stack+0x70/0x184 (unreliable) [c0000000e8ccb070] [c0000000000afebc] .validate_chain+0x6ec/0xf58 [c0000000e8ccb180] [c0000000000b0ff0] .__lock_acquire+0x8c8/0x974 [c0000000e8ccb280] [c0000000000b2290] .lock_acquire+0x140/0x18c [c0000000e8ccb350] [c000000000468df0] ._spin_lock+0x48/0x70 [c0000000e8ccb3e0] [c0000000001407f4] .kmem_cache_free+0x118/0x2d4 [c0000000e8ccb4a0] [c000000000140b90] .free_block+0x130/0x1a8 [c0000000e8ccb540] [c000000000140f94] .__drain_alien_cache+0x80/0xb8 [c0000000e8ccb5e0] [c0000000001411e0] .kfree+0x214/0x324 [c0000000e8ccb6a0] [c0000000003ca860] .skb_release_data+0xe8/0x104 [c0000000e8ccb730] [c0000000003ca2ec] .__kfree_skb+0x20/0xd4 [c0000000e8ccb7b0] [c0000000003cf2c8] .skb_free_datagram+0x1c/0x5c [c0000000e8ccb830] [c00000000045597c] .unix_dgram_recvmsg+0x2f4/0x338 [c0000000e8ccb920] [c0000000003c0f14] .sock_recvmsg+0xf4/0x13c [c0000000e8ccbb30] [c0000000003c28ec] .SyS_recvfrom+0xb4/0x130 [c0000000e8ccbcb0] [c0000000003bfb78] .sys_recv+0x18/0x2c [c0000000e8ccbd20] [c0000000003ed388] .compat_sys_recv+0x14/0x28 [c0000000e8ccbd90] [c0000000003ee1bc] .compat_sys_socketcall+0x178/0x220 [c0000000e8ccbe30] [c0000000000085d4] syscall_exit+0x0/0x40 This patch fixes the issue by setting up lockdep annotations during CPU hotplug. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
This commit is contained in:
Pekka Enberg
parent
648f4e3e50
commit
ce79ddc8e2
136
mm/slab.c
136
mm/slab.c
@ -604,67 +604,6 @@ static struct kmem_cache cache_cache = {
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#define BAD_ALIEN_MAGIC 0x01020304ul
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#ifdef CONFIG_LOCKDEP
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/*
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* Slab sometimes uses the kmalloc slabs to store the slab headers
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* for other slabs "off slab".
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* The locking for this is tricky in that it nests within the locks
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* of all other slabs in a few places; to deal with this special
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* locking we put on-slab caches into a separate lock-class.
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*
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* We set lock class for alien array caches which are up during init.
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* The lock annotation will be lost if all cpus of a node goes down and
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* then comes back up during hotplug
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*/
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static struct lock_class_key on_slab_l3_key;
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static struct lock_class_key on_slab_alc_key;
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static inline void init_lock_keys(void)
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{
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int q;
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struct cache_sizes *s = malloc_sizes;
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while (s->cs_size != ULONG_MAX) {
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for_each_node(q) {
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struct array_cache **alc;
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int r;
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struct kmem_list3 *l3 = s->cs_cachep->nodelists[q];
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if (!l3 || OFF_SLAB(s->cs_cachep))
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continue;
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lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
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alc = l3->alien;
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/*
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* FIXME: This check for BAD_ALIEN_MAGIC
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* should go away when common slab code is taught to
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* work even without alien caches.
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* Currently, non NUMA code returns BAD_ALIEN_MAGIC
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* for alloc_alien_cache,
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*/
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if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
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continue;
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for_each_node(r) {
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if (alc[r])
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lockdep_set_class(&alc[r]->lock,
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&on_slab_alc_key);
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}
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}
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s++;
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}
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}
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#else
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static inline void init_lock_keys(void)
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{
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}
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#endif
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/*
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* Guard access to the cache-chain.
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*/
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static DEFINE_MUTEX(cache_chain_mutex);
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static struct list_head cache_chain;
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/*
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* chicken and egg problem: delay the per-cpu array allocation
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* until the general caches are up.
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@ -685,6 +624,79 @@ int slab_is_available(void)
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return g_cpucache_up >= EARLY;
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}
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#ifdef CONFIG_LOCKDEP
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/*
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* Slab sometimes uses the kmalloc slabs to store the slab headers
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* for other slabs "off slab".
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* The locking for this is tricky in that it nests within the locks
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* of all other slabs in a few places; to deal with this special
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* locking we put on-slab caches into a separate lock-class.
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*
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* We set lock class for alien array caches which are up during init.
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* The lock annotation will be lost if all cpus of a node goes down and
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* then comes back up during hotplug
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*/
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static struct lock_class_key on_slab_l3_key;
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static struct lock_class_key on_slab_alc_key;
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static void init_node_lock_keys(int q)
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{
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struct cache_sizes *s = malloc_sizes;
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if (g_cpucache_up != FULL)
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return;
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for (s = malloc_sizes; s->cs_size != ULONG_MAX; s++) {
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struct array_cache **alc;
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struct kmem_list3 *l3;
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int r;
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l3 = s->cs_cachep->nodelists[q];
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if (!l3 || OFF_SLAB(s->cs_cachep))
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return;
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lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
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alc = l3->alien;
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/*
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* FIXME: This check for BAD_ALIEN_MAGIC
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* should go away when common slab code is taught to
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* work even without alien caches.
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* Currently, non NUMA code returns BAD_ALIEN_MAGIC
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* for alloc_alien_cache,
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*/
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if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
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return;
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for_each_node(r) {
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if (alc[r])
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lockdep_set_class(&alc[r]->lock,
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&on_slab_alc_key);
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}
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}
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}
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static inline void init_lock_keys(void)
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{
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int node;
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for_each_node(node)
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init_node_lock_keys(node);
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}
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#else
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static void init_node_lock_keys(int q)
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{
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}
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static inline void init_lock_keys(void)
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{
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}
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#endif
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/*
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* Guard access to the cache-chain.
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*/
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static DEFINE_MUTEX(cache_chain_mutex);
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static struct list_head cache_chain;
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static DEFINE_PER_CPU(struct delayed_work, reap_work);
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static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
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@ -1254,6 +1266,8 @@ static int __cpuinit cpuup_prepare(long cpu)
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kfree(shared);
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free_alien_cache(alien);
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}
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init_node_lock_keys(node);
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return 0;
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bad:
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cpuup_canceled(cpu);
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