Messages in this thread | | | Date | Thu, 28 Aug 2014 05:58:41 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] rcu: Make nocb leader kthreads process pending callbacks after spawning |
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On Thu, Aug 28, 2014 at 11:16:49AM +0530, Amit Shah wrote: > On (Wed) 27 Aug 2014 [16:43:40], Pranith Kumar wrote: > > The nocb callbacks generated before the nocb kthreads are spawned are > > enqueued in the nocb queue for later processing. Commit fbce7497ee5af ("rcu: > > Parallelize and economize NOCB kthread wakeups") introduced nocb leader kthreads > > which checked the nocb_leader_wake flag to see if there were any such pending > > callbacks. A case was reported in which newly spawned leader kthreads were not > > processing the pending callbacks as this flag was not set, which led to a boot > > hang. > > > > The following commit ensures that the newly spawned nocb kthreads process the > > pending callbacks by allowing the kthreads to run immediately after spawning > > instead of waiting. This is done by inverting the logic of nocb_leader_wake > > tests to nocb_leader_sleep which allows us to use the default initialization of > > this flag to 0 to let the kthreads run. > > > > Reported-by: Amit Shah <amit.shah@redhat.com> > > Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> > > Link: http://www.spinics.net/lists/kernel/msg1802899.html > > --- > > kernel/rcu/tree.h | 2 +- > > kernel/rcu/tree_plugin.h | 24 ++++++++++++------------ > > 2 files changed, 13 insertions(+), 13 deletions(-) > > I'd have split this into two patches: one for the variable rename and > one for fixing the bug. > > However, the backport Paul posted does work fine for me on master, so > you can add my > > Tested-by: Amit Shah <amit.shah@redhat.com>
Thank you again, Amit, both for finding this problem and for your testing efforts!
Thanx, Paul
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