4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiri Olsa <jolsa@xxxxxxxxxx> commit 49ec8f5b6ae3ab60385492cad900ffc8a523c895 upstream. The rdtgroup_kn_unlock waits for the last user to release and put its node. But it's calling kernfs_put on the node which calls the rdtgroup_kn_unlock, which might not be the group's directory node, but another group's file node. This race could be easily reproduced by running 2 instances of following script: mount -t resctrl resctrl /sys/fs/resctrl/ pushd /sys/fs/resctrl/ mkdir krava echo "krava" > krava/schemata rmdir krava popd umount /sys/fs/resctrl It triggers the slub debug error message with following command line config: slub_debug=,kernfs_node_cache. Call kernfs_put on the group's node to fix it. Fixes: 60cf5e101fd4 ("x86/intel_rdt: Add mkdir to resctrl file system") Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Shaohua Li <shli@xxxxxx> Link: http://lkml.kernel.org/r/1489501253-20248-1-git-send-email-jolsa@xxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -727,7 +727,7 @@ void rdtgroup_kn_unlock(struct kernfs_no if (atomic_dec_and_test(&rdtgrp->waitcount) && (rdtgrp->flags & RDT_DELETED)) { kernfs_unbreak_active_protection(kn); - kernfs_put(kn); + kernfs_put(rdtgrp->kn); kfree(rdtgrp); } else { kernfs_unbreak_active_protection(kn);