> 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
>
> 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->delaywork.func is null, if not invoke init_srcu_struct_fields()
> before unloading modules, in srcu_module_going() the __flush_work() find
> work->func is empty, will raise the warning above.
>
> This commit add init_srcu_struct_fields() to initialize srcu structure's->sup,
> in srcu_module_coming().
>
> Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
>
>Good catch, and thank you for testing the in-module case!
>
>One question below...
>
> Thanx, Paul
>
> ---
> kernel/rcu/srcutree.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> index 1fb078abbdc9..42d8720e016c 100644
> --- a/kernel/rcu/srcutree.c
> +++ b/kernel/rcu/srcutree.c
> @@ -1921,7 +1921,8 @@ 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);
> + if (WARN_ON_ONCE(init_srcu_struct_fields(ssp, true)))
> + return -ENOMEM;
>
>Wouldn't it be better to simply delete the init_srcu_struct_data()?
>
>Then the first call to check_init_srcu_struct() would take care of
>the initialization, just as for the non-module case. Or am I missing
>something subtle?
Hi Paul
Maybe the check_init_srcu_struct() is always not invoked, for example,
In rcutorture.c, here is such a definition DEFINE_STATIC_SRCU(srcu_ctl),
but we use torture_type=rcu to test, there will not be any interface calling
check_init_srcu_struct() to initialize srcu_ctl and set structure's->delaywork.func
is process_srcu().
when we unload the rcutorture module, invoke cleanup_srcu_struct()
to flush sup structure's->delaywork.func, due to the func pointer is not initialize,
it's null, will trigger warning.
About kernel/workqueue.c:3167
__flush_work
if (WARN_ON(!work->func)) <---------trigger waning
return false;
and in init_srcu_struct_fields(ssp, true), wil set srcu_sup->sda_is_static is true
and set srcu_sup-> srcu_gp_seq_needed is zero, after that when we call
check_init_srcu_struct() again, it not be initialized again.
Thanks
Zqiang
>
>It should also be possible to eliminate duplicate code between the
>in-module and non-module statically allocated initialization cases,
>come to think of it.
>
> }
> return 0;
> }
> @@ -1931,9 +1932,13 @@ 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++);
> + cleanup_srcu_struct(ssp);
> + free_percpu(ssp->sda);
> + }
>
>And good catch on another memory leak with this one, looks proper
>to me.
>
> }
>
> /* Handle one module, either coming or going. */
> --
> 2.25.1
>
