Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 01/55] sparc32: destroy_context() and switch_mm() needs to disable interrupts. | Date | Tue, 24 Mar 2015 16:42:41 +0100 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: Andreas Larsson <andreas@gaisler.com>
[ Upstream commit 66d0f7ec9f1038452178b1993fc07fd96d30fd38 ]
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@gaisler.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/sparc/mm/srmmu.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/arch/sparc/mm/srmmu.c +++ b/arch/sparc/mm/srmmu.c @@ -455,10 +455,12 @@ static void __init sparc_context_init(in 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); } @@ -983,14 +985,15 @@ int init_new_context(struct task_struct 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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