On Wed, Jan 21, 2015 at 02:54:05PM +0800, Zhang Zhen wrote:
> On 2015/1/21 11:13, Zhang Zhen wrote:
> > On 2015/1/21 10:26, Zhang Zhen wrote:
> >> On 2015/1/20 23:25, Don Zickus wrote:
[ . . . ]
> > Sorry, i made a mistake, the log above is based on v3.10.63.
> > I have tested the latest upstream kernel (based on ec6f34e5b552),
> > but my test case can't triggered RCU stall warning.
> >
>
> I used git bisect to find the bad commit, but found a irrelevant
> commit(db5d711e2db776 zram: avoid null access when fail to alloc meta).
> Before this commit, my test case can easily trigger RCU stall warning,
> but after this commit, my test case can't trigger RCU stall warning.
I have lost track of exactly what kernel you are using. If you are
using a recent kernel (v3.18 or thereabouts), one thing to try is to
apply my stack of RCU CPU stall-warning changes that are on their way
in, please see v3.19-rc1..630181c4a915 in -rcu, which is at:
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
These handle the problems that Dave Jones and a few others located this
past December. Could you please give them a spin?
Thanx, Paul
> I'm totally confused.
>
> My test case:
>
> //
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/spinlock.h>
> #include <linux/slab.h>
> #include <linux/kthread.h>
>
> struct foo {
> int a;
> char b;
> long c;
> };
>
> struct foo gbl_foo = {1, 'a', 2};
> struct foo *pgbl_foo = &gbl_foo;
>
> static int my_kthread(void *data)
> {
> DEFINE_SPINLOCK(foo_mutex);
> struct foo *new_fp;
> struct foo *old_fp;
>
> new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL);
> spin_lock(&foo_mutex);
> old_fp = pgbl_foo;
> *new_fp = *old_fp;
> new_fp->a = 2;
> rcu_assign_pointer(pgbl_foo, new_fp);
> spin_unlock(&foo_mutex);
> synchronize_rcu();
> kfree(old_fp);
>
> return 0;
> }
>
> static int hello_start(void)
> {
> struct task_struct *my_task = NULL;
> DEFINE_SPINLOCK(hello_lock);
>
> my_task = kthread_run(my_kthread, NULL, "my_thread%d", 1);
>
> spin_lock_init(&hello_lock);
> spin_lock(&hello_lock);
> spin_lock(&hello_lock);
> return 0;
> }
>
> static int __init test_init(void)
> {
> hello_start();
>
> printk(KERN_INFO "Module init\n");
> return 0;
> }
>
> static void __exit test_exit(void)
> {
> printk(KERN_INFO "Module exit!\n");
> }
>
> module_init(test_init)
> module_exit(test_exit)
> MODULE_LICENSE("GPL");
> //
> >>>
> >>> Cheers,
> >>> Don
> >>>
> >>> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> >>> index 70bf118..833c015 100644
> >>> --- a/kernel/watchdog.c
> >>> +++ b/kernel/watchdog.c
> >>> @@ -209,7 +209,7 @@ void touch_nmi_watchdog(void)
> >>> * going off.
> >>> */
> >>> raw_cpu_write(watchdog_nmi_touch, true);
> >>> - touch_softlockup_watchdog();
> >>> + //touch_softlockup_watchdog();
> >>> }
> >>> EXPORT_SYMBOL(touch_nmi_watchdog);
> >>>
> >>>
> >>> .
> >>>
> >>
> >
>
>
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