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Messages in this thread Complete thread (EXPERIMENTAL) |
Hello!
This fixes a oops encountered when doing hibernate/resume in presence of PREEMPT_RCU. The problem was that the code failed to disable preemption when accessing a per-CPU variable. This is OK when called from code that already has preemption disabled, but such is not the case from the suspend/resume code path. Well, rcu_offline_cpu() is called from the cpu-offline callback path, and AFAICS, it doesn't disable preemption. I wonder how we're seeing this only now! Indeed a good catch! Reviewed-by: Gautham R Shenoy <ego@in.ibm.com> Reported-by: Dave Young <hidave.darkstar@gmail.com> Tested-by: Dave Young <hidave.darkstar@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- rcupreempt.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -urpNa -X dontdiff linux-2.6.25-rc3/kernel/rcupreempt.c linux-2.6.25-rc3-rcuoffline/kernel/rcupreempt.c --- linux-2.6.25-rc3/kernel/rcupreempt.c 2008-02-26 16:58:43.000000000 -0800 +++ linux-2.6.25-rc3-rcuoffline/kernel/rcupreempt.c 2008-02-26 17:04:17.000000000 -0800 @@ -702,8 +702,9 @@ void rcu_offline_cpu(int cpu) * fix. */ + local_irq_save(flags); rdp = RCU_DATA_ME(); - spin_lock_irqsave(&rdp->lock, flags); + spin_lock(&rdp->lock); *rdp->nexttail = list; if (list) rdp->nexttail = tail; -- Thanks and Regards gautham | ||||||||||
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