On Fri, Nov 21, 2014 at 9:58 AM, Kirill A. Shutemov <[email protected]> wrote: > On Fri, Nov 21, 2014 at 09:30:36AM -0500, Pranith Kumar wrote: >> On 11/21/2014 08:31 AM, Kirill A. Shutemov wrote: >> > On Tue, Oct 28, 2014 at 03:09:56PM -0700, Paul E. McKenney wrote: >> >> From: Pranith Kumar <[email protected]> >> >> >> >> Got Paul's email wrong the first time. >> >> >> >> The map field in 'struct mapped_device' is an rcu pointer. Use >> >> rcu_dereference() >> >> while accessing it. >> >> >> >> Signed-off-by: Pranith Kumar <[email protected]> >> >> Signed-off-by: Paul E. McKenney <[email protected]> >> > >> > On current -next I see this: >> > >> > [ 6.388264] =============================== >> > [ 6.389571] [ INFO: suspicious RCU usage. ] >> > [ 6.390869] 3.18.0-rc5-next-20141121-08303-g44cae4530372 #2 Not tainted >> > [ 6.392185] ------------------------------- >> > [ 6.393479] /home/kas/git/public/linux/drivers/md/dm.c:2853 suspicious >> > rcu_dereference_check() usage! >> > [ 6.394801] >> > other info that might help us debug this: >> > >> >> Hi Kirill, >> >> We are dereferencing an RCU pointer with the suspend_lock held which is >> causing this warning. >> >> Can you please check if the following patch helps? Thanks! > > Nope. The same issue. > > IIUC, the problem is that you dereference pointer outside rcu_read_lock() > section, not that suspend_lock is held. >
I am not sure we should be taking rcu_read_lock() there as I am not sure how long that critical section might last. Can someone who is more familiar with the code take a look? I will try to look for a solution too in the mean time. Thanks! -- Pranith -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
