Re: [PATCH 1/2] Move kfree_call_rcu() to slab_common.c

From: Rao Shoaib
Date: Thu Jan 04 2018 - 15:36:34 EST


Hi Boqun,

Thanks a lot for all your guidance and for catching the cut and paster error. Please see inline.


On 01/03/2018 05:38 PM, Boqun Feng wrote:

But you introduced a bug here, you should use rcu_state_p instead of
&rcu_sched_state as the third parameter for __call_rcu().

Please re-read:

https://marc.info/?l=linux-mm&m=151390529209639

, and there are other comments, which you still haven't resolved in this
version. You may want to write a better commit log to explain the
reasons of each modifcation and fix bugs or typos in your previous
version. That's how review process works ;-)

Regards,
Boqun

This is definitely a serious error. Thanks for catching this.

As far as your previous comments are concerned, only the following one has not been addressed. Can you please elaborate as I do not understand the comment. The code was expanded because the new macro expansion check fails. Based on Matthew Wilcox's comment I have reverted rcu_head_name back to rcu_head.

+#define kfree_rcu(ptr, rcu_head_name) \
+ do { \
+ typeof(ptr) __ptr = ptr; \
+ unsigned long __off = offsetof(typeof(*(__ptr)), \
+ rcu_head_name); \
+ struct rcu_head *__rptr = (void *)__ptr + __off; \
+ __kfree_rcu(__rptr, __off); \
+ } while (0)

why do you want to open code this?

Does the following text for the commit log looks better.

kfree_rcu() should use the new kfree_bulk() interface for freeing rcu structures

The newly implemented kfree_bulk() interfaces are more efficient, using the interfaces for freeing rcu structures has shown performance improvements in synthetic benchmarks that allocate and free rcu structures at a high rate.

Shoaib