[PATCH] sched, mm: Use activate_mm() instead of switch_mm()

[Catalin Marinas]

The ARM port tries to remove __ARCH_WANT_INTERRUPTS_ON_CTXSW. Since the
actual pgd switching requires interrupts to be enabled on ARM (for
latency on ARMv5 and earlier and IPIs on ARMv6+), the solution is to
defer the pgd switching to a post context switch hook that is run with
interrupts enabled. There are however two additional direct calls to
switch_mm() without the additional post-switch hook and ARM would fail
to set the new pgd.

This patch changes the switch_mm() call with activate_mm() which ensures
that the required pgd has been set. The activate_mm() function must be
called with interrupts enabled.

Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
 kernel/sched.c   |    2 +-
 mm/mmu_context.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 7b46a39..3976157 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6310,7 +6310,7 @@ void idle_task_exit(void)
 	BUG_ON(cpu_online(smp_processor_id()));
 
 	if (mm != &init_mm)
-		switch_mm(mm, &init_mm, current);
+		activate_mm(mm, &init_mm);
 	mmdrop(mm);
 }
 
diff --git a/mm/mmu_context.c b/mm/mmu_context.c
index cf332bc..4e44ac4 100644
--- a/mm/mmu_context.c
+++ b/mm/mmu_context.c
@@ -32,7 +32,7 @@ void use_mm(struct mm_struct *mm)
 		tsk->active_mm = mm;
 	}
 	tsk->mm = mm;
-	switch_mm(active_mm, mm, tsk);
+	activate_mm(active_mm, mm);
 	task_unlock(tsk);
 
 	if (active_mm != mm)

-- 
Catalin
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/