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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-02-22 17:05:03 -0800
committerIngo Molnar <mingo@elte.hu>2010-02-25 10:34:59 +0100
commit3acd9eb31c5f7eb97cb2009fa41472710fb4a10f (patch)
treea339775ed9683bdf0f4d7b47a75648a6f86a8446 /kernel/sys.c
parent1304afb225288a2e250d6a7495462c28e5509cbb (diff)
downloadlwn-3acd9eb31c5f7eb97cb2009fa41472710fb4a10f.tar.gz
lwn-3acd9eb31c5f7eb97cb2009fa41472710fb4a10f.zip
rcu: Fix deadlock in TREE_PREEMPT_RCU CPU stall detection
Under TREE_PREEMPT_RCU, print_other_cpu_stall() invokes rcu_print_task_stall() with the root rcu_node structure's ->lock held, and rcu_print_task_stall() acquires that same lock for self-deadlock. Fix this by removing the lock acquisition from rcu_print_task_stall(), and making all callers acquire the lock instead. Tested-by: John Kacur <jkacur@redhat.com> Tested-by: Thomas Gleixner <tglx@linutronix.de> Located-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-19-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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