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author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-03-15 19:16:26 (GMT) |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-05-01 15:22:50 (GMT) |
commit | f511fc624642f0bb8cf65aaa28979737514d4746 (patch) | |
tree | db1395c5d33da33c8ea6c82f6e5b7346cc5beb91 /drivers | |
parent | 79b9a75fb703b6a2670e46b9dc495af5bc7029b3 (diff) | |
download | linux-fsl-qoriq-f511fc624642f0bb8cf65aaa28979737514d4746.tar.xz |
rcu: Ensure that RCU_FAST_NO_HZ timers expire on correct CPU
Timers are subject to migration, which can lead to the following
system-hang scenario when CONFIG_RCU_FAST_NO_HZ=y:
1. CPU 0 executes synchronize_rcu(), which posts an RCU callback.
2. CPU 0 then goes idle. It cannot immediately invoke the callback,
but there is nothing RCU needs from ti, so it enters dyntick-idle
mode after posting a timer.
3. The timer gets migrated to CPU 1.
4. CPU 0 never wakes up, so the synchronize_rcu() never returns, so
the system hangs.
This commit fixes this problem by using mod_timer_pinned(), as suggested
by Peter Zijlstra, to ensure that the timer is actually posted on the
running CPU.
Reported-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'drivers')
0 files changed, 0 insertions, 0 deletions