This is a note to let you know that I've just added the patch titled tcp: md5: do not use alloc_percpu() to the 3.17-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tcp-md5-do-not-use-alloc_percpu.patch and it can be found in the queue-3.17 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Fri Nov 7 11:36:50 PST 2014 From: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Thu, 23 Oct 2014 12:58:58 -0700 Subject: tcp: md5: do not use alloc_percpu() From: Eric Dumazet <edumazet@xxxxxxxxxx> [ Upstream commit 349ce993ac706869d553a1816426d3a4bfda02b1 ] percpu tcp_md5sig_pool contains memory blobs that ultimately go through sg_set_buf(). -> sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); This requires that whole area is in a physically contiguous portion of memory. And that @buf is not backed by vmalloc(). Given that alloc_percpu() can use vmalloc() areas, this does not fit the requirements. Replace alloc_percpu() by a static DEFINE_PER_CPU() as tcp_md5sig_pool is small anyway, there is no gain to dynamically allocate it. Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Fixes: 765cf9976e93 ("tcp: md5: remove one indirection level in tcp_md5sig_pool") Reported-by: Crestez Dan Leonard <cdleonard@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv4/tcp.c | 59 +++++++++++++++++++-------------------------------------- 1 file changed, 20 insertions(+), 39 deletions(-) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2985,61 +2985,42 @@ EXPORT_SYMBOL(compat_tcp_getsockopt); #endif #ifdef CONFIG_TCP_MD5SIG -static struct tcp_md5sig_pool __percpu *tcp_md5sig_pool __read_mostly; +static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool); static DEFINE_MUTEX(tcp_md5sig_mutex); - -static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool __percpu *pool) -{ - int cpu; - - for_each_possible_cpu(cpu) { - struct tcp_md5sig_pool *p = per_cpu_ptr(pool, cpu); - - if (p->md5_desc.tfm) - crypto_free_hash(p->md5_desc.tfm); - } - free_percpu(pool); -} +static bool tcp_md5sig_pool_populated = false; static void __tcp_alloc_md5sig_pool(void) { int cpu; - struct tcp_md5sig_pool __percpu *pool; - - pool = alloc_percpu(struct tcp_md5sig_pool); - if (!pool) - return; for_each_possible_cpu(cpu) { - struct crypto_hash *hash; + if (!per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm) { + struct crypto_hash *hash; - hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); - if (IS_ERR_OR_NULL(hash)) - goto out_free; - - per_cpu_ptr(pool, cpu)->md5_desc.tfm = hash; + hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); + if (IS_ERR_OR_NULL(hash)) + return; + per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm = hash; + } } - /* before setting tcp_md5sig_pool, we must commit all writes - * to memory. See ACCESS_ONCE() in tcp_get_md5sig_pool() + /* before setting tcp_md5sig_pool_populated, we must commit all writes + * to memory. See smp_rmb() in tcp_get_md5sig_pool() */ smp_wmb(); - tcp_md5sig_pool = pool; - return; -out_free: - __tcp_free_md5sig_pool(pool); + tcp_md5sig_pool_populated = true; } bool tcp_alloc_md5sig_pool(void) { - if (unlikely(!tcp_md5sig_pool)) { + if (unlikely(!tcp_md5sig_pool_populated)) { mutex_lock(&tcp_md5sig_mutex); - if (!tcp_md5sig_pool) + if (!tcp_md5sig_pool_populated) __tcp_alloc_md5sig_pool(); mutex_unlock(&tcp_md5sig_mutex); } - return tcp_md5sig_pool != NULL; + return tcp_md5sig_pool_populated; } EXPORT_SYMBOL(tcp_alloc_md5sig_pool); @@ -3053,13 +3034,13 @@ EXPORT_SYMBOL(tcp_alloc_md5sig_pool); */ struct tcp_md5sig_pool *tcp_get_md5sig_pool(void) { - struct tcp_md5sig_pool __percpu *p; - local_bh_disable(); - p = ACCESS_ONCE(tcp_md5sig_pool); - if (p) - return __this_cpu_ptr(p); + if (tcp_md5sig_pool_populated) { + /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */ + smp_rmb(); + return this_cpu_ptr(&tcp_md5sig_pool); + } local_bh_enable(); return NULL; } Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are queue-3.17/vxlan-fix-a-free-after-use.patch queue-3.17/macvlan-fix-a-race-on-port-dismantle-and-possible-skb-leaks.patch queue-3.17/ipv4-fix-nexthop-attlen-check-in-fib_nh_match.patch queue-3.17/net-fix-saving-tx-flow-hash-in-sock-for-outgoing-connections.patch queue-3.17/ipv4-dst_entry-leak-in-ip_send_unicast_reply.patch queue-3.17/tcp-md5-do-not-use-alloc_percpu.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html