| Message ID | 1418905403-11154-1-git-send-email-andreas@gaisler.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
From: Andreas Larsson <andreas@gaisler.com> Date: Thu, 18 Dec 2014 13:23:23 +0100 > 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> Looks good, applied, thanks Andreas. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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; } }
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> --- arch/sparc/mm/srmmu.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)