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Commit 66d0f7ec authored by Andreas Larsson's avatar Andreas Larsson Committed by David S. Miller
Browse files

sparc32: destroy_context() and switch_mm() needs to disable interrupts. 



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 77b838fa ("[SPARC64]: destroy_context() needs to disable
interrupts.")

Signed-off-by: default avatarAndreas Larsson <andreas@gaisler.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 44e8967d

arch/sparc/mm/srmmu.c

+7 −4
Original line number Original line Diff line number Diff line
@@ -460,10 +460,12 @@ static void __init sparc_context_init(int numctx) 
void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm,

void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm,

	       struct task_struct *tsk)

	       struct task_struct *tsk)

{

{

	unsigned long flags;



	if (mm->context == NO_CONTEXT) {

	if (mm->context == NO_CONTEXT) {

		spin_lock(&srmmu_context_spinlock);

		spin_lock_irqsave(&srmmu_context_spinlock, flags);

		alloc_context(old_mm, mm);

		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);

		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)

void destroy_context(struct mm_struct *mm)

{

{

	unsigned long flags;





	if (mm->context != NO_CONTEXT) {

	if (mm->context != NO_CONTEXT) {

		flush_cache_mm(mm);

		flush_cache_mm(mm);

		srmmu_ctxd_set(&srmmu_context_table[mm->context], srmmu_swapper_pg_dir);

		srmmu_ctxd_set(&srmmu_context_table[mm->context], srmmu_swapper_pg_dir);

		flush_tlb_mm(mm);

		flush_tlb_mm(mm);

		spin_lock(&srmmu_context_spinlock);

		spin_lock_irqsave(&srmmu_context_spinlock, flags);

		free_context(mm->context);

		free_context(mm->context);

		spin_unlock(&srmmu_context_spinlock);

		spin_unlock_irqrestore(&srmmu_context_spinlock, flags);

		mm->context = NO_CONTEXT;

		mm->context = NO_CONTEXT;

	}

	}

}

}