Re: [PATCH -next] fork: silence a false postive warning in __mmdrop

2020-09-08 Thread peterz
On Tue, Sep 08, 2020 at 12:50:44PM -0400, Qian Cai wrote: > > No, you're talking nonsense. We must not free @mm when > > 'current->active_mm == mm', never. > > Yes, you are right. It still trigger this below on powerpc with today's > linux-next by fuzzing for a while (saw a few times on recent

Re: [PATCH -next] fork: silence a false postive warning in __mmdrop

2020-09-08 Thread Qian Cai
On Wed, Jul 22, 2020 at 03:44:06PM +0200, Peter Zijlstra wrote: > On Wed, Jul 22, 2020 at 09:19:00AM -0400, Qian Cai wrote: > > On Wed, Jul 22, 2020 at 12:06:37PM +0200, pet...@infradead.org wrote: > > > On Thu, Jun 04, 2020 at 11:03:44AM -0400, Qian Cai wrote: > > > > The linux-next commit

Re: [PATCH -next] fork: silence a false postive warning in __mmdrop

2020-07-22 Thread Peter Zijlstra
On Wed, Jul 22, 2020 at 09:19:00AM -0400, Qian Cai wrote: > On Wed, Jul 22, 2020 at 12:06:37PM +0200, pet...@infradead.org wrote: > > On Thu, Jun 04, 2020 at 11:03:44AM -0400, Qian Cai wrote: > > > The linux-next commit bf2c59fce407 ("sched/core: Fix illegal RCU from > > > offline CPUs") delayed,

Re: [PATCH -next] fork: silence a false postive warning in __mmdrop

2020-07-22 Thread Qian Cai
On Wed, Jul 22, 2020 at 12:06:37PM +0200, pet...@infradead.org wrote: > On Thu, Jun 04, 2020 at 11:03:44AM -0400, Qian Cai wrote: > > The linux-next commit bf2c59fce407 ("sched/core: Fix illegal RCU from > > offline CPUs") delayed, > > > > idle->active_mm = _mm; > > > > into finish_cpu() instead

Re: [PATCH -next] fork: silence a false postive warning in __mmdrop

2020-07-22 Thread peterz
On Thu, Jun 04, 2020 at 11:03:44AM -0400, Qian Cai wrote: > The linux-next commit bf2c59fce407 ("sched/core: Fix illegal RCU from > offline CPUs") delayed, > > idle->active_mm = _mm; > > into finish_cpu() instead of idle_task_exit() which results in a false > positive warning that was originally

Re: [PATCH -next] fork: silence a false postive warning in __mmdrop

2020-07-21 Thread Qian Cai
On Thu, Jun 04, 2020 at 11:03:44AM -0400, Qian Cai wrote: > The linux-next commit bf2c59fce407 ("sched/core: Fix illegal RCU from > offline CPUs") delayed, > > idle->active_mm = _mm; > > into finish_cpu() instead of idle_task_exit() which results in a false > positive warning that was originally

[PATCH -next] fork: silence a false postive warning in __mmdrop

2020-06-04 Thread Qian Cai
The linux-next commit bf2c59fce407 ("sched/core: Fix illegal RCU from offline CPUs") delayed, idle->active_mm = _mm; into finish_cpu() instead of idle_task_exit() which results in a false positive warning that was originally designed in the commit 3eda69c92d47 ("kernel/fork.c: detect early free