diff options
| author | Michael Bringmann <mwb@linux.vnet.ibm.com> | 2017-07-27 16:27:14 -0500 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2017-07-28 11:05:52 -0400 |
| commit | 1ad0f0a7aa1bf3bd42dcd108a96713d255eacd9f (patch) | |
| tree | adad9ec5dd0a10141e3b30b57c2fa83264c77e18 | |
| parent | 0a94efb5acbb6980d7c9ab604372d93cd507e4d8 (diff) | |
workqueue: Work around edge cases for calc of pool's cpumask
There is an underlying assumption/trade-off in many layers of the Linux
system that CPU <-> node mapping is static. This is despite the presence
of features like NUMA and 'hotplug' that support the dynamic addition/
removal of fundamental system resources like CPUs and memory. PowerPC
systems, however, do provide extensive features for the dynamic change
of resources available to a system.
Currently, there is little or no synchronization protection around the
updating of the CPU <-> node mapping, and the export/update of this
information for other layers / modules. In systems which can change
this mapping during 'hotplug', like PowerPC, the information is changing
underneath all layers that might reference it.
This patch attempts to ensure that a valid, usable cpumask attribute
is used by the workqueue infrastructure when setting up new resource
pools. It prevents a crash that has been observed when an 'empty'
cpumask is passed along to the worker/task scheduling code. It is
intended as a temporary workaround until a more fundamental review and
correction of the issue can be done.
[With additions to the patch provided by Tejun Hao <tj@kernel.org>]
Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | kernel/workqueue.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 7146ea70a62d..ca937b0c3a96 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3577,6 +3577,13 @@ static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, /* yeap, return possible CPUs in @node that @attrs wants */ cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); + + if (cpumask_empty(cpumask)) { + pr_warn_once("WARNING: workqueue cpumask: online intersect > " + "possible intersect\n"); + return false; + } + return !cpumask_equal(cpumask, attrs->cpumask); use_dfl: |