Load balancing can be triggered in the critical sections protected by
srmmu_context_spinlock in destroy_context() and switch_mm() and can hang
the cpu waiting for the rq lock of another cpu that in turn has called
switch_mm hangning on srmmu_context_spinlock leading to deadlock.
So, disable interrupt while taking srmmu_context_spinlock in
destroy_context() and switch_mm() so we don't deadlock.
See also commit 77b838fa1ef0 ("[SPARC64]: destroy_context() needs to disable
interrupts.")
Signed-off-by: Andreas Larsson <andr...@gaisler.com>
---
arch/sparc/mm/srmmu.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index be65f03..5cbc96d 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -460,10 +460,12 @@ static void __init sparc_context_init(int numctx)
void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm,
struct task_struct *tsk)
{
+ unsigned long flags;
+
if (mm->context == NO_CONTEXT) {
- spin_lock(&srmmu_context_spinlock);
+ spin_lock_irqsave(&srmmu_context_spinlock, flags);
alloc_context(old_mm, mm);
- spin_unlock(&srmmu_context_spinlock);
+ spin_unlock_irqrestore(&srmmu_context_spinlock, flags);
srmmu_ctxd_set(&srmmu_context_table[mm->context], mm->pgd);
}
@@ -986,14 +988,15 @@ int init_new_context(struct task_struct *tsk, struct
mm_struct *mm)
void destroy_context(struct mm_struct *mm)
{
+ unsigned long flags;
if (mm->context != NO_CONTEXT) {
flush_cache_mm(mm);
srmmu_ctxd_set(&srmmu_context_table[mm->context],
srmmu_swapper_pg_dir);
flush_tlb_mm(mm);
- spin_lock(&srmmu_context_spinlock);
+ spin_lock_irqsave(&srmmu_context_spinlock, flags);
free_context(mm->context);
- spin_unlock(&srmmu_context_spinlock);
+ spin_unlock_irqrestore(&srmmu_context_spinlock, flags);
mm->context = NO_CONTEXT;
}
}
--
1.7.10.4
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