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authorPaul Mackerras <paulus@samba.org>2014-01-18 21:14:47 +1100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-06 11:22:22 -0800
commit50692bdd5cde9f86d1f96f50627d2fbf266ee783 (patch)
parent634bcdd9a104b791eec3f808d6ee4f1e565303e2 (diff)
powerpc: Make sure "cache" directory is removed when offlining cpu
commit 91b973f90c1220d71923e7efe1e61f5329806380 upstream. The code in remove_cache_dir() is supposed to remove the "cache" subdirectory from the sysfs directory for a CPU when that CPU is being offlined. It tries to do this by calling kobject_put() on the kobject for the subdirectory. However, the subdirectory only gets removed once the last reference goes away, and the reference being put here may well not be the last reference. That means that the "cache" subdirectory may still exist when the offlining operation has finished. If the same CPU subsequently gets onlined, the code tries to add a new "cache" subdirectory. If the old subdirectory has not yet been removed, we get a WARN_ON in the sysfs code, with stack trace, and an error message printed on the console. Further, we ultimately end up with an online cpu with no "cache" subdirectory. This fixes it by doing an explicit kobject_del() at the point where we want the subdirectory to go away. kobject_del() removes the sysfs directory even though the object still exists in memory. The object will get freed at some point in the future. A subsequent onlining operation can create a new sysfs directory, even if the old object still exists in memory, without causing any problems. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/cacheinfo.c b/arch/powerpc/kernel/cacheinfo.c
index 654932727873..bfb82365bc7a 100644
--- a/arch/powerpc/kernel/cacheinfo.c
+++ b/arch/powerpc/kernel/cacheinfo.c
@@ -794,6 +794,9 @@ static void remove_cache_dir(struct cache_dir *cache_dir)
+ /* Remove cache dir from sysfs */
+ kobject_del(cache_dir->kobj);