Messages in this thread | | | From | Joel Fernandes <> | Date | Tue, 24 Sep 2019 08:15:12 -0400 | Subject | Re: [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'. |
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On Tue, Sep 24, 2019 at 4:05 AM Dan Carpenter <dan.carpenter@oracle.com> wrote: > > tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2019.09.23a > head: 97de53b94582c208ee239178b208b8e8b9472585 > commit: 39676bb72323718a9e7bab1ba9c4a68319a96f62 [62/77] rcu: Add support for debug_objects debugging for kfree_rcu() > > If you fix the issue, kindly add following tag > Reported-by: kbuild test robot <lkp@intel.com> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com> > > smatch warnings: > kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'. > Locked on: line 2867 > Unlocked on: line 2882 > > git remote add rcu https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git > git remote update rcu > git checkout 39676bb72323718a9e7bab1ba9c4a68319a96f62 > vim +2882 kernel/rcu/tree.c > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2850) void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2851) { > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2852) unsigned long flags; > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2853) struct kfree_rcu_cpu *krcp; > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2854) > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2855) head->func = func; > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2856) > 87970ccf5a9125 Paul E. McKenney 2019-09-19 2857 local_irq_save(flags); // For safely calling this_cpu_ptr(). > ^^^^^^^^^^^^^^^^^^^^^ > IRQs disabled. > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2858) krcp = this_cpu_ptr(&krc); > ff8db005e371cb Paul E. McKenney 2019-09-19 2859 if (krcp->initialized) > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2860) spin_lock(&krcp->lock); > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2861) > 87970ccf5a9125 Paul E. McKenney 2019-09-19 2862 // Queue the object but don't yet schedule the batch. > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2863) if (debug_rcu_head_queue(head)) { > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2864) // Probable double kfree_rcu(), just leak. > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2865) WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n", > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2866) __func__, head); > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2867) return; > > Need to re-enable before returning.
Right. At this point the system has a bug anyway since it is a double-free. But yes, no reason to introduce more bugs. Will fix. Thank you, Dan!
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