4.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jiri Olsa <jo...@kernel.org>
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 <jo...@kernel.org>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Mike Galbraith <efa...@gmx.de>
Cc: Shaohua Li <s...@fb.com>
Link:
http://lkml.kernel.org/r/1489501253-20248-1-git-send-email-jo...@kernel.org
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
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);
