| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20180731092219.28908-1-jiada_wang@mentor.com>
Date: Tue, 31 Jul 2018 18:22:19 +0900
From: <jiada_wang@...tor.com>
To: <mingo@...hat.com>, <peterz@...radead.org>
CC: <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/1] sched/debug: fix potential deadlock when write to sched_features
From: Jiada Wang <jiada_wang@...tor.com>
Following lockdep report can be triggered by write to
/sys/kernel/debug/sched_features
[ 43.094116] ======================================================
[ 43.100345] WARNING: possible circular locking dependency detected
[ 43.106581] 4.18.0-rc6-00152-gcd3f77d74ac3-dirty #18 Not tainted
[ 43.112635] ------------------------------------------------------
[ 43.118864] sh/3358 is trying to acquire lock:
[ 43.123351] 000000004ad3989d (cpu_hotplug_lock.rw_sem){++++}, at: static_key_enable+0x14/0x30
[ 43.132008]
[ 43.132008] but task is already holding lock:
[ 43.137893] 00000000c1b31a88 (&sb->s_type->i_mutex_key#3){+.+.}, at: sched_feat_write+0x160/0x428
[ 43.146886]
[ 43.146886] which lock already depends on the new lock.
[ 43.146886]
[ 43.155136]
[ 43.155136] the existing dependency chain (in reverse order) is:
[ 43.162681]
[ 43.162681] -> #3 (&sb->s_type->i_mutex_key#3){+.+.}:
[ 43.169314] lock_acquire+0xb8/0x148
[ 43.173462] down_write+0xac/0x140
[ 43.177430] start_creating+0x5c/0x168
[ 43.181743] debugfs_create_dir+0x18/0x220
[ 43.186414] opp_debug_register+0x8c/0x120
[ 43.191077] _add_opp_dev+0x104/0x1f8
[ 43.195306] dev_pm_opp_get_opp_table+0x174/0x340
[ 43.200581] _of_add_opp_table_v2+0x110/0x760
[ 43.205508] dev_pm_opp_of_add_table+0x5c/0x240
[ 43.210609] dev_pm_opp_of_cpumask_add_table+0x5c/0x100
[ 43.216409] cpufreq_init+0x160/0x430
[ 43.220634] cpufreq_online+0x1cc/0xe30
[ 43.225033] cpufreq_add_dev+0x78/0x198
[ 43.229439] subsys_interface_register+0x168/0x270
[ 43.234803] cpufreq_register_driver+0x1c8/0x278
[ 43.239990] dt_cpufreq_probe+0xdc/0x1b8
[ 43.244482] platform_drv_probe+0xb4/0x168
[ 43.249145] driver_probe_device+0x318/0x4b0
[ 43.253982] __device_attach_driver+0xfc/0x1f0
[ 43.258994] bus_for_each_drv+0xf8/0x180
[ 43.263480] __device_attach+0x164/0x200
[ 43.267968] device_initial_probe+0x10/0x18
[ 43.272716] bus_probe_device+0x110/0x178
[ 43.277298] device_add+0x6d8/0x908
[ 43.281351] platform_device_add+0x138/0x3d8
[ 43.286191] platform_device_register_full+0x1cc/0x1f8
[ 43.291910] cpufreq_dt_platdev_init+0x174/0x1bc
[ 43.297102] do_one_initcall+0xb8/0x310
[ 43.301508] kernel_init_freeable+0x4b8/0x56c
[ 43.306433] kernel_init+0x10/0x138
[ 43.310485] ret_from_fork+0x10/0x18
[ 43.314616]
[ 43.314616] -> #2 (opp_table_lock){+.+.}:
[ 43.320189] lock_acquire+0xb8/0x148
[ 43.324329] __mutex_lock+0x104/0xf50
[ 43.328557] mutex_lock_nested+0x1c/0x28
[ 43.333047] _of_add_opp_table_v2+0xb4/0x760
[ 43.337886] dev_pm_opp_of_add_table+0x5c/0x240
[ 43.342988] dev_pm_opp_of_cpumask_add_table+0x5c/0x100
[ 43.348786] cpufreq_init+0x160/0x430
[ 43.353011] cpufreq_online+0x1cc/0xe30
[ 43.357410] cpufreq_add_dev+0x78/0x198
[ 43.361811] subsys_interface_register+0x168/0x270
[ 43.367175] cpufreq_register_driver+0x1c8/0x278
[ 43.372362] dt_cpufreq_probe+0xdc/0x1b8
[ 43.376852] platform_drv_probe+0xb4/0x168
[ 43.381515] driver_probe_device+0x318/0x4b0
[ 43.386352] __device_attach_driver+0xfc/0x1f0
[ 43.391363] bus_for_each_drv+0xf8/0x180
[ 43.395850] __device_attach+0x164/0x200
[ 43.400338] device_initial_probe+0x10/0x18
[ 43.405088] bus_probe_device+0x110/0x178
[ 43.409665] device_add+0x6d8/0x908
[ 43.413718] platform_device_add+0x138/0x3d8
[ 43.418559] platform_device_register_full+0x1cc/0x1f8
[ 43.424270] cpufreq_dt_platdev_init+0x174/0x1bc
[ 43.429457] do_one_initcall+0xb8/0x310
[ 43.433857] kernel_init_freeable+0x4b8/0x56c
[ 43.438782] kernel_init+0x10/0x138
[ 43.442834] ret_from_fork+0x10/0x18
[ 43.446965]
[ 43.446965] -> #1 (subsys mutex#6){+.+.}:
[ 43.452545] lock_acquire+0xb8/0x148
[ 43.456684] __mutex_lock+0x104/0xf50
[ 43.460911] mutex_lock_nested+0x1c/0x28
[ 43.465400] subsys_interface_register+0xd8/0x270
[ 43.470677] cpufreq_register_driver+0x1c8/0x278
[ 43.475864] dt_cpufreq_probe+0xdc/0x1b8
[ 43.480354] platform_drv_probe+0xb4/0x168
[ 43.485017] driver_probe_device+0x318/0x4b0
[ 43.489854] __device_attach_driver+0xfc/0x1f0
[ 43.494865] bus_for_each_drv+0xf8/0x180
[ 43.499352] __device_attach+0x164/0x200
[ 43.503840] device_initial_probe+0x10/0x18
[ 43.508589] bus_probe_device+0x110/0x178
[ 43.513166] device_add+0x6d8/0x908
[ 43.517218] platform_device_add+0x138/0x3d8
[ 43.522058] platform_device_register_full+0x1cc/0x1f8
[ 43.527768] cpufreq_dt_platdev_init+0x174/0x1bc
[ 43.532955] do_one_initcall+0xb8/0x310
[ 43.537356] kernel_init_freeable+0x4b8/0x56c
[ 43.542281] kernel_init+0x10/0x138
[ 43.546333] ret_from_fork+0x10/0x18
[ 43.550464]
[ 43.550464] -> #0 (cpu_hotplug_lock.rw_sem){++++}:
[ 43.556822] __lock_acquire+0x203c/0x21d0
[ 43.561397] lock_acquire+0xb8/0x148
[ 43.565543] cpus_read_lock+0x58/0x1c8
[ 43.569857] static_key_enable+0x14/0x30
[ 43.574347] sched_feat_write+0x314/0x428
[ 43.578924] full_proxy_write+0xa0/0x138
[ 43.583415] __vfs_write+0xd8/0x388
[ 43.587465] vfs_write+0xdc/0x318
[ 43.591340] ksys_write+0xb4/0x138
[ 43.595302] sys_write+0xc/0x18
[ 43.599004] __sys_trace_return+0x0/0x4
[ 43.603397]
[ 43.603397] other info that might help us debug this:
[ 43.603397]
[ 43.611473] Chain exists of:
[ 43.611473] cpu_hotplug_lock.rw_sem --> opp_table_lock --> &sb->s_type->i_mutex_key#3
[ 43.611473]
[ 43.623971] Possible unsafe locking scenario:
[ 43.623971]
[ 43.629943] CPU0 CPU1
[ 43.634510] ---- ----
[ 43.639077] lock(&sb->s_type->i_mutex_key#3);
[ 43.643667] lock(opp_table_lock);
[ 43.649733] lock(&sb->s_type->i_mutex_key#3);
[ 43.656854] lock(cpu_hotplug_lock.rw_sem);
[ 43.661175]
[ 43.661175] *** DEADLOCK ***
[ 43.661175]
[ 43.667157] 2 locks held by sh/3358:
[ 43.670765] #0: 00000000a8c4b363 (sb_writers#10){.+.+}, at: vfs_write+0x238/0x318
[ 43.678444] #1: 00000000c1b31a88 (&sb->s_type->i_mutex_key#3){+.+.}, at: sched_feat_write+0x160/0x428
[ 43.687872]
[ 43.687872] stack backtrace:
[ 43.692284] CPU: 5 PID: 3358 Comm: sh Not tainted 4.18.0-rc6-00152-gcd3f77d74ac3-dirty #18
[ 43.700616] Hardware name: Renesas H3ULCB Kingfisher board based on r8a7795 ES2.0+ (DT)
[ 43.708684] Call trace:
[ 43.711169] dump_backtrace+0x0/0x288
[ 43.714873] show_stack+0x14/0x20
[ 43.718226] dump_stack+0x13c/0x1ac
[ 43.721754] print_circular_bug.isra.10+0x270/0x438
[ 43.726679] check_prev_add.constprop.16+0x4dc/0xb98
[ 43.731690] __lock_acquire+0x203c/0x21d0
[ 43.735740] lock_acquire+0xb8/0x148
[ 43.739357] cpus_read_lock+0x58/0x1c8
[ 43.743147] static_key_enable+0x14/0x30
[ 43.747112] sched_feat_write+0x314/0x428
[ 43.751163] full_proxy_write+0xa0/0x138
[ 43.755125] __vfs_write+0xd8/0x388
[ 43.758651] vfs_write+0xdc/0x318
[ 43.762001] ksys_write+0xb4/0x138
[ 43.765438] sys_write+0xc/0x18
[ 43.768615] __sys_trace_return+0x0/0x4
This is because load of cpufreq_dt module firstly acquires
cpu_hotplug_lock.rw_sem lock, then in cpufreq_init, it holds
&sb->s_type->i_mutex_key lock.
But write to /sys/kernel/debug/sched_features, cpu_hotplug_lock.rw_sem lock
depends on &sb->s_type->i_mutex_key lock.
This patch by reversing the lock acquisition order when write to
sched_features, this way cpu_hotplug_lock.rw_sem no longer depends on
&sb->s_type->i_mutex_key.
Cc: George G. Davis <george_davis@...tor.com>
Cc: Eugeniu Rosca <erosca@...adit-jv.com>
Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
---
kernel/sched/debug.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index e593b4118578..deefa9569bcf 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -87,21 +87,21 @@ struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
#undef SCHED_FEAT
-static void sched_feat_disable(int i)
+static void sched_feat_disable_cpuslocked(int i)
{
- static_key_disable(&sched_feat_keys[i]);
+ static_key_disable_cpuslocked(&sched_feat_keys[i]);
}
-static void sched_feat_enable(int i)
+static void sched_feat_enable_cpuslocked(int i)
{
- static_key_enable(&sched_feat_keys[i]);
+ static_key_enable_cpuslocked(&sched_feat_keys[i]);
}
#else
-static void sched_feat_disable(int i) { };
-static void sched_feat_enable(int i) { };
+static void sched_feat_disable_cpuslocked(int i) { };
+static void sched_feat_enable_cpuslocked(int i) { };
#endif /* HAVE_JUMP_LABEL */
-static int sched_feat_set(char *cmp)
+static int sched_feat_set_cpuslocked(char *cmp)
{
int i;
int neg = 0;
@@ -115,10 +115,10 @@ static int sched_feat_set(char *cmp)
if (strcmp(cmp, sched_feat_names[i]) == 0) {
if (neg) {
sysctl_sched_features &= ~(1UL << i);
- sched_feat_disable(i);
+ sched_feat_disable_cpuslocked(i);
} else {
sysctl_sched_features |= (1UL << i);
- sched_feat_enable(i);
+ sched_feat_enable_cpuslocked(i);
}
break;
}
@@ -147,9 +147,11 @@ sched_feat_write(struct file *filp, const char __user *ubuf,
/* Ensure the static_key remains in a consistent state */
inode = file_inode(filp);
+ cpus_read_lock();
inode_lock(inode);
- i = sched_feat_set(cmp);
+ i = sched_feat_set_cpuslocked(cmp);
inode_unlock(inode);
+ cpus_read_unlock();
if (i == __SCHED_FEAT_NR)
return -EINVAL;
--
2.17.0
Powered by blists - more mailing lists