The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x ba9182a89626d5f83c2ee4594f55cb9c1e60f0e2 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023041703-swoop-hankering-5a8c@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^.. Possible dependencies: ba9182a89626 ("cgroup/cpuset: Wake up cpuset_attach_wq tasks in cpuset_cancel_attach()") 1243dc518c9d ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem") f9a25f776d78 ("cpusets: Rebuild root domain deadline accounting information") 933a90bf4f35 ("Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ba9182a89626d5f83c2ee4594f55cb9c1e60f0e2 Mon Sep 17 00:00:00 2001 From: Waiman Long <longman@xxxxxxxxxx> Date: Tue, 11 Apr 2023 09:35:57 -0400 Subject: [PATCH] cgroup/cpuset: Wake up cpuset_attach_wq tasks in cpuset_cancel_attach() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After a successful cpuset_can_attach() call which increments the attach_in_progress flag, either cpuset_cancel_attach() or cpuset_attach() will be called later. In cpuset_attach(), tasks in cpuset_attach_wq, if present, will be woken up at the end. That is not the case in cpuset_cancel_attach(). So missed wakeup is possible if the attach operation is somehow cancelled. Fix that by doing the wakeup in cpuset_cancel_attach() as well. Fixes: e44193d39e8d ("cpuset: let hotplug propagation work wait for task attaching") Signed-off-by: Waiman Long <longman@xxxxxxxxxx> Reviewed-by: Michal Koutný <mkoutny@xxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx # v3.11+ Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index f310915d1257..ff7eb8e2efdc 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2502,11 +2502,15 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) static void cpuset_cancel_attach(struct cgroup_taskset *tset) { struct cgroup_subsys_state *css; + struct cpuset *cs; cgroup_taskset_first(tset, &css); + cs = css_cs(css); percpu_down_write(&cpuset_rwsem); - css_cs(css)->attach_in_progress--; + cs->attach_in_progress--; + if (!cs->attach_in_progress) + wake_up(&cpuset_attach_wq); percpu_up_write(&cpuset_rwsem); }
