When CONFIG_PREEMPT=y, CONFIG_IPV6=m and CONFIG_SEG6_HMAC=y,
seg6_hmac_init() is called during the initialization of the ipv6 module.
This causes a subsequent call to smp_processor_id() with preemption
enabled, resulting in the following trace.
[ 20.451460] BUG: using smp_processor_id() in preemptible [00000000] code:
systemd/1
[ 20.452556] caller is debug_smp_processor_id+0x17/0x19
[ 20.453304] CPU: 0 PID: 1 Comm: systemd Not tainted 4.9.0-rc5-00973-g46738b1
#1
[ 20.454406] ffffc9000062fc18 ffffffff813607b2 0000000000000000
ffffffff81a7f782
[ 20.455528] ffffc9000062fc48 ffffffff813778dc 0000000000000000
00000000001dcf98
[ 20.456539] ffffffffa003bd08 ffffffff81af93e0 ffffc9000062fc58
ffffffff81377905
[ 20.456539] Call Trace:
[ 20.456539] [<ffffffff813607b2>] dump_stack+0x63/0x7f
[ 20.456539] [<ffffffff813778dc>] check_preemption_disabled+0xd1/0xe3
[ 20.456539] [<ffffffff81377905>] debug_smp_processor_id+0x17/0x19
[ 20.460260] [<ffffffffa0061f3b>] seg6_hmac_init+0xfa/0x192 [ipv6]
[ 20.460260] [<ffffffffa0061ccc>] seg6_init+0x39/0x6f [ipv6]
[ 20.460260] [<ffffffffa006121a>] inet6_init+0x21a/0x321 [ipv6]
[ 20.460260] [<ffffffffa0061000>] ? 0xffffffffa0061000
[ 20.460260] [<ffffffff81000457>] do_one_initcall+0x8b/0x115
[ 20.460260] [<ffffffff811328a3>] do_init_module+0x53/0x1c4
[ 20.460260] [<ffffffff8110650a>] load_module+0x1153/0x14ec
[ 20.460260] [<ffffffff81106a7b>] SYSC_finit_module+0x8c/0xb9
[ 20.460260] [<ffffffff81106a7b>] ? SYSC_finit_module+0x8c/0xb9
[ 20.460260] [<ffffffff81106abc>] SyS_finit_module+0x9/0xb
[ 20.460260] [<ffffffff810014d1>] do_syscall_64+0x62/0x75
[ 20.460260] [<ffffffff816834f0>] entry_SYSCALL64_slow_path+0x25/0x25
This patch disable BHs in seg6_hmac_init() and seg6_hmac_exit(). BHs are
re-enabled for the call to crypto_alloc_shash. Indeed, this function might
call try_module_get(), which cannot be called in atomic context.
Signed-off-by: David Lebrun <david.leb...@uclouvain.be>
---
net/ipv6/seg6_hmac.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
index ef1c8a4..ab2ceb4 100644
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c
@@ -363,7 +363,7 @@ static int seg6_hmac_init_ring(void)
return -ENOMEM;
for_each_possible_cpu(i) {
- char *ring = kzalloc(SEG6_HMAC_RING_SIZE, GFP_KERNEL);
+ char *ring = kzalloc(SEG6_HMAC_RING_SIZE, GFP_ATOMIC);
if (!ring)
return -ENOMEM;
@@ -393,7 +393,9 @@ static int seg6_hmac_init_algo(void)
return -ENOMEM;
for_each_possible_cpu(cpu) {
- tfm = crypto_alloc_shash(algo->name, 0, GFP_KERNEL);
+ local_bh_enable();
+ tfm = crypto_alloc_shash(algo->name, 0, GFP_ATOMIC);
+ local_bh_disable();
if (IS_ERR(tfm))
return PTR_ERR(tfm);
p_tfm = per_cpu_ptr(algo->tfms, cpu);
@@ -410,7 +412,7 @@ static int seg6_hmac_init_algo(void)
return -ENOMEM;
for_each_possible_cpu(cpu) {
- shash = kzalloc(shsize, GFP_KERNEL);
+ shash = kzalloc(shsize, GFP_ATOMIC);
if (!shash)
return -ENOMEM;
*per_cpu_ptr(algo->shashs, cpu) = shash;
@@ -424,6 +426,8 @@ int __init seg6_hmac_init(void)
{
int ret;
+ local_bh_disable();
+
ret = seg6_hmac_init_ring();
if (ret < 0)
goto out;
@@ -431,6 +435,7 @@ int __init seg6_hmac_init(void)
ret = seg6_hmac_init_algo();
out:
+ local_bh_enable();
return ret;
}
EXPORT_SYMBOL(seg6_hmac_init);
@@ -450,6 +455,8 @@ void seg6_hmac_exit(void)
struct seg6_hmac_algo *algo = NULL;
int i, alg_count, cpu;
+ local_bh_disable();
+
for_each_possible_cpu(i) {
char *ring = *per_cpu_ptr(hmac_ring, i);
@@ -472,6 +479,8 @@ void seg6_hmac_exit(void)
free_percpu(algo->tfms);
free_percpu(algo->shashs);
}
+
+ local_bh_enable();
}
EXPORT_SYMBOL(seg6_hmac_exit);
--
2.7.3
