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Date: Wed, 25 Mar 2015 14:02:03 +0000 From: Luis Henriques <luis.henriques@...onical.com> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org, kernel-team@...ts.ubuntu.com Cc: Andreas Larsson <andreas@...sler.com>, "David S. Miller" <davem@...emloft.net>, Luis Henriques <luis.henriques@...onical.com> Subject: [PATCH 3.16.y-ckt 150/165] sparc32: destroy_context() and switch_mm() needs to disable interrupts. 3.16.7-ckt9 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Andreas Larsson <andreas@...sler.com> commit 66d0f7ec9f1038452178b1993fc07fd96d30fd38 upstream. 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 <andreas@...sler.com> Signed-off-by: David S. Miller <davem@...emloft.net> Signed-off-by: Luis Henriques <luis.henriques@...onical.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 be65f035d18a..5cbc96d801ff 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; } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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