Re: [GIT PULL rcu/urgent] Fix two more 4.3 regressions

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Sun, Sep 27, 2015 at 09:37:05AM +0200, Sedat Dilek wrote:
> On Sun, Sep 27, 2015 at 9:32 AM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
> > On Sun, Sep 27, 2015 at 08:28:39AM +0200, Sedat Dilek wrote:
> >> Hi,
> >>
> >> as I have observed here some lockdep issues (one could be solved in
> >> netdev) I wanted to try this patchset.
> >>
> >> Unfortunately, you cannot pull from...
> >>
> >> "These changes are available in the git repository at:
> >>
> >>   git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo
> >>
> >> for you to fetch changes up to 19a5ecde086a6a5287978b12ae948fa691b197b7:
> >>
> >>   rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex
> >> (2015-09-20 21:01:22 -0700)
> >>
> >> ----------------------------------------------------------------
> >> Oleg Nesterov (1):
> >>       rcu: Change _wait_rcu_gp() to work around GCC bug 67055
> >>
> >> Paul E. McKenney (1):
> >>       rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex
> >>
> >>  include/linux/rcupdate.h | 11 +++++------
> >>  kernel/rcu/tree.c        |  5 +++++
> >>  2 files changed, 10 insertions(+), 6 deletions(-)"
> >>
> >> So, I have stolen them from linux-next.git.
> >>
> >> Please look at this, Thanks.
> >
> > Does it work better now?  (Forgot to actually push the new name...)
> 
> Hi Paul,
> 
> now for-mingo Git branch has this two fixes.

Whew!!!  Apologies for the hassle!

> I just booted into my new kernel with the "stolen" rcu.fixes from -next.
> 
> For the lockdep problems I will do a CONFIG_DEBUG_LOCKDEP=y to see if
> I get some more infos on the workqueue trouble.
> 
> [   23.874836] BUG: sleeping function called from invalid context at
> kernel/workqueue.c:2678
> [   23.874902] in_atomic(): 0, irqs_disabled(): 1, pid: 1411, name: acpid

Did you get a stack trace?  There are quite a few potential callers of
start_flush_work() via flush_work().

> $ grep LOCKDEP /boot/config-4.3.0-rc2-438.1-llvmlinux-amd64
> CONFIG_LOCKDEP_SUPPORT=y
> CONFIG_LOCKDEP=y
> # CONFIG_DEBUG_LOCKDEP is not set
> 
> So, CLANG is a bit different compiler :-).

True enough.  Good to have more than one, though.

							Thanx, Paul

> Thanks for taking care.
> 
> Regards,
> - Sedat -
> 
> >>
> >> [1] http://marc.info/?l=linux-kernel&m=144332758307978&w=2
> >> [2] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/patch/?id=66e8c57da6bf6b847a48a5a6fda59512f733ed78
> >> [3] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/patch/?id=19a5ecde086a6a5287978b12ae948fa691b197b7
> >>
> >
>