From 49ec8f5b6ae3ab60385492cad900ffc8a523c895 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 14 Mar 2017 15:20:53 +0100 Subject: [PATCH] x86/intel_rdt: Put group node in rdtgroup_kn_unlock 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 Cc: Fenghua Yu Cc: Peter Zijlstra Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Shaohua Li Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1489501253-20248-1-git-send-email-jolsa@kernel.org Signed-off-by: Thomas Gleixner --- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index c05509d..9ac2a5c 100644 --- 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_node *kn) 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); -- 2.7.4