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authorTejun Heo <tj@kernel.org>2017-05-24 12:03:48 -0400
committerTejun Heo <tj@kernel.org>2017-05-24 12:43:30 -0400
commit41c25707d21716826e3c1f60967f5550610ec1c9 (patch)
tree41092221c68b8ec835d5a00e9d38440e67d613b9 /kernel
parent33c35aa4817864e056fd772230b0c6b552e36ea2 (diff)
downloadlinux-41c25707d21716826e3c1f60967f5550610ec1c9.tar.bz2
cpuset: consider dying css as offline
In most cases, a cgroup controller don't care about the liftimes of cgroups. For the controller, a css becomes online when ->css_online() is called on it and offline when ->css_offline() is called. However, cpuset is special in that the user interface it exposes cares whether certain cgroups exist or not. Combined with the RCU delay between cgroup removal and css offlining, this can lead to user visible behavior oddities where operations which should succeed after cgroup removals fail for some time period. The effects of cgroup removals are delayed when seen from userland. This patch adds css_is_dying() which tests whether offline is pending and updates is_cpuset_online() so that the function returns false also while offline is pending. This gets rid of the userland visible delays. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Daniel Jordan <daniel.m.jordan@oracle.com> Link: http://lkml.kernel.org/r/327ca1f5-7957-fbb9-9e5f-9ba149d40ba2@oracle.com Cc: stable@vger.kernel.org Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup/cpuset.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index f6501f4f6040..ae643412948a 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -176,9 +176,9 @@ typedef enum {
} cpuset_flagbits_t;
/* convenient tests for these bits */
-static inline bool is_cpuset_online(const struct cpuset *cs)
+static inline bool is_cpuset_online(struct cpuset *cs)
{
- return test_bit(CS_ONLINE, &cs->flags);
+ return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css);
}
static inline int is_cpu_exclusive(const struct cpuset *cs)