On 2015/07/12 10:19, Waiman Long wrote: > Enabling locking-selftest in a VM guest may cause the following > kernel panic: > > kernel BUG at .../kernel/locking/qspinlock_paravirt.h:137! > > This is due to the fact that the pvqspinlock unlock function is > expecting either a _Q_LOCKED_VAL or _Q_SLOW_VAL in the lock byte. This > patch prevents that bug report by ignoring it when debug_locks_silent > is set. Otherwise, a warning will be printed if it contains an > unexpected value. > > With this patch applied, the kernel locking-selftest completed without > any noise. >
OK, I've tested this with make allmodconfig && make localmodconfig kernel. (I've hit another issue to boot, but it seems not related to this issue) Tested-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> Thank you! > Signed-off-by: Waiman Long <waiman.l...@hp.com> > --- > kernel/locking/qspinlock_paravirt.h | 12 +++++++++++- > 1 files changed, 11 insertions(+), 1 deletions(-) > > diff --git a/kernel/locking/qspinlock_paravirt.h > b/kernel/locking/qspinlock_paravirt.h > index 04ab181..15d3733 100644 > --- a/kernel/locking/qspinlock_paravirt.h > +++ b/kernel/locking/qspinlock_paravirt.h > @@ -4,6 +4,7 @@ > > #include <linux/hash.h> > #include <linux/bootmem.h> > +#include <linux/debug_locks.h> > > /* > * Implement paravirt qspinlocks; the general idea is to halt the vcpus > instead > @@ -286,15 +287,24 @@ __visible void __pv_queued_spin_unlock(struct qspinlock > *lock) > { > struct __qspinlock *l = (void *)lock; > struct pv_node *node; > + u8 lockval = cmpxchg(&l->locked, _Q_LOCKED_VAL, 0); > > /* > * We must not unlock if SLOW, because in that case we must first > * unhash. Otherwise it would be possible to have multiple @lock > * entries, which would be BAD. > */ > - if (likely(cmpxchg(&l->locked, _Q_LOCKED_VAL, 0) == _Q_LOCKED_VAL)) > + if (likely(lockval == _Q_LOCKED_VAL)) > return; > > + if (unlikely(lockval != _Q_SLOW_VAL)) { > + if (debug_locks_silent) > + return; > + WARN(1, "pvqspinlock: lock 0x%lx has corrupted value 0x%x!\n", > + (unsigned long)lock, atomic_read(&lock->val)); > + return; > + } > + > /* > * Since the above failed to release, this must be the SLOW path. > * Therefore start by looking up the blocked node and unhashing it. > -- Masami HIRAMATSU Linux Technology Research Center, System Productivity Research Dept. Center for Technology Innovation - Systems Engineering Hitachi, Ltd., Research & Development Group E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/