When unloading rcutorture kmod will trigger the following callstack:
insmod rcutorture.ko
rmmod rcutorture.ko
[ 209.437327] WARNING: CPU: 0 PID: 508 at kernel/workqueue.c:3167 __flush_work+0x50a/0x540
[ 209.437346] Modules linked in: rcutorture(-) torture [last unloaded: rcutorture]
[ 209.437382] CPU: 0 PID: 508 Comm: rmmod Tainted: G W 6.3.0-rc1-yocto-standard+
[ 209.437406] RIP: 0010:__flush_work+0x50a/0x540
.....
[ 209.437758] flush_delayed_work+0x36/0x90
[ 209.437776] cleanup_srcu_struct+0x68/0x2e0
[ 209.437817] srcu_module_notify+0x71/0x140
[ 209.437854] blocking_notifier_call_chain+0x9d/0xd0
[ 209.437880] __x64_sys_delete_module+0x223/0x2e0
[ 209.438046] do_syscall_64+0x43/0x90
[ 209.438062] entry_SYSCALL_64_after_hwframe+0x72/0xdc
flush_delayed_work()
->__flush_work()
->if (WARN_ON(!work->func))
return false;
For srcu objects defined with DEFINE_SRCU() or DEFINE_STATIC_SRCU(),
when compiling and loading as modules, the srcu_module_coming() is
invoked, allocate memory for srcu structure's->sda and initialize
sda structure, due to not fully initialize srcu structure's->sup,
so at this time the sup structure's->work.work.func is null, if not
invoke init_srcu_struct_fields() before unloading modules, the
__flush_work() be invoked in srcu_module_going() and find work->func
is empty, will raise the warning above.
This commit add the check of srcu_sup structure's->srcu_gp_seq_needed
to determine whether the check_init_srcu_struct() has been invoked to
initialize srcu objects in srcu_module_going(), if not initialize, there
are no pending or running works, so there is no need to flush, only invoke
free_percpu() to release srcu structure's->sda.
Co-developed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
---
kernel/rcu/srcutree.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 1fb078abbdc9..edf894e3b96e 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -1921,7 +1921,6 @@ static int srcu_module_coming(struct module *mod)
ssp->sda = alloc_percpu(struct srcu_data);
if (WARN_ON_ONCE(!ssp->sda))
return -ENOMEM;
- init_srcu_struct_data(ssp);
}
return 0;
}
@@ -1931,9 +1930,14 @@ static void srcu_module_going(struct module *mod)
{
int i;
struct srcu_struct **sspp = mod->srcu_struct_ptrs;
+ struct srcu_struct *ssp;
- for (i = 0; i < mod->num_srcu_structs; i++)
- cleanup_srcu_struct(*(sspp++));
+ for (i = 0; i < mod->num_srcu_structs; i++) {
+ ssp = (*sspp++);
+ if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_sup->srcu_gp_seq_needed)))
+ cleanup_srcu_struct(ssp);
+ free_percpu(ssp->sda);
+ }
}
/* Handle one module, either coming or going. */
--
2.25.1
