sparc32: destroy_context() and switch_mm() needs to disable interrupts. (66d0f7ec) · Commits · 戴 / test

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 ("[SPARC64]: destroy_context() needs to disable interrupts.") Signed-off-by:

Andreas Larsson <andreas@gaisler.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

arch/sparc/mm/srmmu.c

+7 −4

Original line number	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,
		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;
		}
		}

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