127 lines
3.4 KiB
Diff
127 lines
3.4 KiB
Diff
From 69181f2ef2ee3ef5f638c925216133e9d47abbfe Mon Sep 17 00:00:00 2001
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From: Ingo Molnar <mingo@elte.hu>
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Date: Fri, 3 Jul 2009 08:30:37 -0500
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Subject: [032/254] mm: Prepare decoupling the page fault disabling logic
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Add a pagefault_disabled variable to task_struct to allow decoupling
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the pagefault-disabled logic from the preempt count.
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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include/linux/sched.h | 1 +
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include/linux/uaccess.h | 33 +++------------------------------
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kernel/fork.c | 1 +
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mm/memory.c | 29 +++++++++++++++++++++++++++++
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4 files changed, 34 insertions(+), 30 deletions(-)
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diff --git a/include/linux/sched.h b/include/linux/sched.h
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index bd5caa1..f0ee37f 100644
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--- a/include/linux/sched.h
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+++ b/include/linux/sched.h
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@@ -1478,6 +1478,7 @@ struct task_struct {
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/* mutex deadlock detection */
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struct mutex_waiter *blocked_on;
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#endif
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+ int pagefault_disabled;
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#ifdef CONFIG_TRACE_IRQFLAGS
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unsigned int irq_events;
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unsigned long hardirq_enable_ip;
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diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
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index 5ca0951..9414a1b 100644
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--- a/include/linux/uaccess.h
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+++ b/include/linux/uaccess.h
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@@ -6,37 +6,10 @@
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/*
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* These routines enable/disable the pagefault handler in that
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- * it will not take any locks and go straight to the fixup table.
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- *
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- * They have great resemblance to the preempt_disable/enable calls
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- * and in fact they are identical; this is because currently there is
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- * no other way to make the pagefault handlers do this. So we do
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- * disable preemption but we don't necessarily care about that.
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+ * it will not take any MM locks and go straight to the fixup table.
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*/
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-static inline void pagefault_disable(void)
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-{
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- inc_preempt_count();
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- /*
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- * make sure to have issued the store before a pagefault
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- * can hit.
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- */
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- barrier();
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-}
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-
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-static inline void pagefault_enable(void)
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-{
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- /*
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- * make sure to issue those last loads/stores before enabling
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- * the pagefault handler again.
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- */
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- barrier();
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- dec_preempt_count();
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- /*
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- * make sure we do..
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- */
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- barrier();
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- preempt_check_resched();
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-}
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+extern void pagefault_disable(void);
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+extern void pagefault_enable(void);
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#ifndef ARCH_HAS_NOCACHE_UACCESS
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diff --git a/kernel/fork.c b/kernel/fork.c
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index b767e68..fdf0795 100644
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--- a/kernel/fork.c
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+++ b/kernel/fork.c
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@@ -1265,6 +1265,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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p->hardirq_context = 0;
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p->softirq_context = 0;
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#endif
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+ p->pagefault_disabled = 0;
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#ifdef CONFIG_LOCKDEP
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p->lockdep_depth = 0; /* no locks held yet */
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p->curr_chain_key = 0;
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diff --git a/mm/memory.c b/mm/memory.c
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index 6105f47..c3b9c80 100644
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--- a/mm/memory.c
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+++ b/mm/memory.c
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@@ -3467,6 +3467,35 @@ unlock:
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return 0;
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}
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+void pagefault_disable(void)
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+{
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+ inc_preempt_count();
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+ current->pagefault_disabled++;
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+ /*
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+ * make sure to have issued the store before a pagefault
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+ * can hit.
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+ */
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+ barrier();
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+}
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+EXPORT_SYMBOL_GPL(pagefault_disable);
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+
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+void pagefault_enable(void)
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+{
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+ /*
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+ * make sure to issue those last loads/stores before enabling
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+ * the pagefault handler again.
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+ */
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+ barrier();
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+ current->pagefault_disabled--;
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+ dec_preempt_count();
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+ /*
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+ * make sure we do..
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+ */
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+ barrier();
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+ preempt_check_resched();
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+}
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+EXPORT_SYMBOL_GPL(pagefault_enable);
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+
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/*
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* By the time we get here, we already hold the mm semaphore
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*/
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