Messages in this thread Patch in this message | | | Date | Tue, 14 Mar 2017 13:55:16 -0700 | From | tip-bot for Jiri Olsa <> | Subject | [tip:x86/urgent] x86/intel_rdt: Put group node in rdtgroup_kn_unlock |
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Commit-ID: 49ec8f5b6ae3ab60385492cad900ffc8a523c895 Gitweb: http://git.kernel.org/tip/49ec8f5b6ae3ab60385492cad900ffc8a523c895 Author: Jiri Olsa <jolsa@kernel.org> AuthorDate: Tue, 14 Mar 2017 15:20:53 +0100 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Tue, 14 Mar 2017 21:51:58 +0100
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 <jolsa@kernel.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Shaohua Li <shli@fb.com> 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 <tglx@linutronix.de>
--- 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);
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