diff options
| author | Lai Jiangshan | 2024-07-11 16:35:43 +0800 |
|---|---|---|
| committer | Tejun Heo | 2024-07-11 12:50:34 -1000 |
| commit | 19af457573838785290d27dd09a59140f541d1d8 (patch) | |
| tree | c11a88c3866deb47af708f2b48437d4f98abc168 /kernel | |
| parent | fbb3d4c15dc0fe8a439de267db927a9ab2f44e98 (diff) | |
workqueue: Remove cpus_read_lock() from apply_wqattrs_lock()
1726a1713590 ("workqueue: Put PWQ allocation and WQ enlistment in the same
lock C.S.") led to the following possible deadlock:
WARNING: possible recursive locking detected
6.10.0-rc5-00004-g1d4c6111406c #1 Not tainted
--------------------------------------------
swapper/0/1 is trying to acquire lock:
c27760f4 (cpu_hotplug_lock){++++}-{0:0}, at: alloc_workqueue (kernel/workqueue.c:5152 kernel/workqueue.c:5730)
but task is already holding lock:
c27760f4 (cpu_hotplug_lock){++++}-{0:0}, at: padata_alloc (kernel/padata.c:1007)
...
stack backtrace:
...
cpus_read_lock (include/linux/percpu-rwsem.h:53 kernel/cpu.c:488)
alloc_workqueue (kernel/workqueue.c:5152 kernel/workqueue.c:5730)
padata_alloc (kernel/padata.c:1007 (discriminator 1))
pcrypt_init_padata (crypto/pcrypt.c:327 (discriminator 1))
pcrypt_init (crypto/pcrypt.c:353)
do_one_initcall (init/main.c:1267)
do_initcalls (init/main.c:1328 (discriminator 1) init/main.c:1345 (discriminator 1))
kernel_init_freeable (init/main.c:1364)
kernel_init (init/main.c:1469)
ret_from_fork (arch/x86/kernel/process.c:153)
ret_from_fork_asm (arch/x86/entry/entry_32.S:737)
entry_INT80_32 (arch/x86/entry/entry_32.S:944)
This is caused by pcrypt allocating a workqueue while holding
cpus_read_lock(), so workqueue code can't do it again as that can lead to
deadlocks if down_write starts after the first down_read.
The pwq creations and installations have been reworked based on
wq_online_cpumask rather than cpu_online_mask making cpus_read_lock() is
unneeded during wqattrs changes. Fix the deadlock by removing
cpus_read_lock() from apply_wqattrs_lock().
tj: Updated changelog.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Fixes: 1726a1713590 ("workqueue: Put PWQ allocation and WQ enlistment in the same lock C.S.")
Link: http://lkml.kernel.org/r/202407081521.83b627c1-lkp@intel.com
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/workqueue.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index a345a72395e7..9b7c1fcd934b 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5113,15 +5113,12 @@ static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, static void apply_wqattrs_lock(void) { - /* CPUs should stay stable across pwq creations and installations */ - cpus_read_lock(); mutex_lock(&wq_pool_mutex); } static void apply_wqattrs_unlock(void) { mutex_unlock(&wq_pool_mutex); - cpus_read_unlock(); } /** |