#include <linux/export.h>
#include <linux/mm.h>
#include <linux/err.h>
+#include <linux/srcu.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/slab.h>
+/* global SRCU for all MMs */
+static struct srcu_struct srcu;
+
/*
* This function can't run concurrently against mmu_notifier_register
* because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
* in parallel despite there being no task using this mm any more,
* through the vmas outside of the exit_mmap context, such as with
* vmtruncate. This serializes against mmu_notifier_unregister with
- * the mmu_notifier_mm->lock in addition to RCU and it serializes
- * against the other mmu notifiers with RCU. struct mmu_notifier_mm
+ * the mmu_notifier_mm->lock in addition to SRCU and it serializes
+ * against the other mmu notifiers with SRCU. struct mmu_notifier_mm
* can't go away from under us as exit_mmap holds an mm_count pin
* itself.
*/
void __mmu_notifier_release(struct mm_struct *mm)
{
struct mmu_notifier *mn;
- struct hlist_node *n;
+ int id;
/*
- * RCU here will block mmu_notifier_unregister until
- * ->release returns.
+ * srcu_read_lock() here will block synchronize_srcu() in
+ * mmu_notifier_unregister() until all registered
+ * ->release() callouts this function makes have
+ * returned.
*/
- rcu_read_lock();
- hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist)
- /*
- * if ->release runs before mmu_notifier_unregister it
- * must be handled as it's the only way for the driver
- * to flush all existing sptes and stop the driver
- * from establishing any more sptes before all the
- * pages in the mm are freed.
- */
- if (mn->ops->release)
- mn->ops->release(mn, mm);
- rcu_read_unlock();
-
+ id = srcu_read_lock(&srcu);
spin_lock(&mm->mmu_notifier_mm->lock);
while (unlikely(!hlist_empty(&mm->mmu_notifier_mm->list))) {
mn = hlist_entry(mm->mmu_notifier_mm->list.first,
struct mmu_notifier,
hlist);
+
/*
- * We arrived before mmu_notifier_unregister so
- * mmu_notifier_unregister will do nothing other than
- * to wait ->release to finish and
- * mmu_notifier_unregister to return.
+ * Unlink. This will prevent mmu_notifier_unregister()
+ * from also making the ->release() callout.
*/
hlist_del_init_rcu(&mn->hlist);
+ spin_unlock(&mm->mmu_notifier_mm->lock);
+
+ /*
+ * Clear sptes. (see 'release' description in mmu_notifier.h)
+ */
+ if (mn->ops->release)
+ mn->ops->release(mn, mm);
+
+ spin_lock(&mm->mmu_notifier_mm->lock);
}
spin_unlock(&mm->mmu_notifier_mm->lock);
/*
- * synchronize_rcu here prevents mmu_notifier_release to
- * return to exit_mmap (which would proceed freeing all pages
- * in the mm) until the ->release method returns, if it was
- * invoked by mmu_notifier_unregister.
- *
- * The mmu_notifier_mm can't go away from under us because one
- * mm_count is hold by exit_mmap.
+ * All callouts to ->release() which we have done are complete.
+ * Allow synchronize_srcu() in mmu_notifier_unregister() to complete
+ */
+ srcu_read_unlock(&srcu, id);
+
+ /*
+ * mmu_notifier_unregister() may have unlinked a notifier and may
+ * still be calling out to it. Additionally, other notifiers
+ * may have been active via vmtruncate() et. al. Block here
+ * to ensure that all notifier callouts for this mm have been
+ * completed and the sptes are really cleaned up before returning
+ * to exit_mmap().
*/
- synchronize_rcu();
+ synchronize_srcu(&srcu);
}
/*
{
struct mmu_notifier *mn;
struct hlist_node *n;
- int young = 0;
+ int young = 0, id;
- rcu_read_lock();
+ id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
if (mn->ops->clear_flush_young)
young |= mn->ops->clear_flush_young(mn, mm, address);
}
- rcu_read_unlock();
+ srcu_read_unlock(&srcu, id);
return young;
}
{
struct mmu_notifier *mn;
struct hlist_node *n;
- int young = 0;
+ int young = 0, id;
- rcu_read_lock();
+ id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
if (mn->ops->test_young) {
young = mn->ops->test_young(mn, mm, address);
break;
}
}
- rcu_read_unlock();
+ srcu_read_unlock(&srcu, id);
return young;
}
{
struct mmu_notifier *mn;
struct hlist_node *n;
+ int id;
- rcu_read_lock();
+ id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
if (mn->ops->change_pte)
mn->ops->change_pte(mn, mm, address, pte);
else if (mn->ops->invalidate_page)
mn->ops->invalidate_page(mn, mm, address);
}
- rcu_read_unlock();
+ srcu_read_unlock(&srcu, id);
}
void __mmu_notifier_invalidate_page(struct mm_struct *mm,
{
struct mmu_notifier *mn;
struct hlist_node *n;
+ int id;
- rcu_read_lock();
+ id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
if (mn->ops->invalidate_page)
mn->ops->invalidate_page(mn, mm, address);
}
- rcu_read_unlock();
+ srcu_read_unlock(&srcu, id);
}
void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
{
struct mmu_notifier *mn;
struct hlist_node *n;
+ int id;
- rcu_read_lock();
+ id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
if (mn->ops->invalidate_range_start)
mn->ops->invalidate_range_start(mn, mm, start, end);
}
- rcu_read_unlock();
+ srcu_read_unlock(&srcu, id);
}
void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
{
struct mmu_notifier *mn;
struct hlist_node *n;
+ int id;
- rcu_read_lock();
+ id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
if (mn->ops->invalidate_range_end)
mn->ops->invalidate_range_end(mn, mm, start, end);
}
- rcu_read_unlock();
+ srcu_read_unlock(&srcu, id);
}
static int do_mmu_notifier_register(struct mmu_notifier *mn,
BUG_ON(atomic_read(&mm->mm_users) <= 0);
+ /*
+ * Verify that mmu_notifier_init() already run and the global srcu is
+ * initialized.
+ */
+ BUG_ON(!srcu.per_cpu_ref);
+
ret = -ENOMEM;
mmu_notifier_mm = kmalloc(sizeof(struct mmu_notifier_mm), GFP_KERNEL);
if (unlikely(!mmu_notifier_mm))
/*
* This releases the mm_count pin automatically and frees the mm
* structure if it was the last user of it. It serializes against
- * running mmu notifiers with RCU and against mmu_notifier_unregister
- * with the unregister lock + RCU. All sptes must be dropped before
+ * running mmu notifiers with SRCU and against mmu_notifier_unregister
+ * with the unregister lock + SRCU. All sptes must be dropped before
* calling mmu_notifier_unregister. ->release or any other notifier
* method may be invoked concurrently with mmu_notifier_unregister,
* and only after mmu_notifier_unregister returned we're guaranteed
{
BUG_ON(atomic_read(&mm->mm_count) <= 0);
+ spin_lock(&mm->mmu_notifier_mm->lock);
if (!hlist_unhashed(&mn->hlist)) {
- /*
- * RCU here will force exit_mmap to wait ->release to finish
- * before freeing the pages.
- */
- rcu_read_lock();
+ int id;
/*
- * exit_mmap will block in mmu_notifier_release to
- * guarantee ->release is called before freeing the
- * pages.
+ * Ensure we synchronize up with __mmu_notifier_release().
*/
+ id = srcu_read_lock(&srcu);
+
+ hlist_del_rcu(&mn->hlist);
+ spin_unlock(&mm->mmu_notifier_mm->lock);
+
if (mn->ops->release)
mn->ops->release(mn, mm);
- rcu_read_unlock();
- spin_lock(&mm->mmu_notifier_mm->lock);
- hlist_del_rcu(&mn->hlist);
+ /*
+ * Allow __mmu_notifier_release() to complete.
+ */
+ srcu_read_unlock(&srcu, id);
+ } else
spin_unlock(&mm->mmu_notifier_mm->lock);
- }
/*
- * Wait any running method to finish, of course including
- * ->release if it was run by mmu_notifier_relase instead of us.
+ * Wait for any running method to finish, including ->release() if it
+ * was run by __mmu_notifier_release() instead of us.
*/
- synchronize_rcu();
+ synchronize_srcu(&srcu);
BUG_ON(atomic_read(&mm->mm_count) <= 0);
mmdrop(mm);
}
EXPORT_SYMBOL_GPL(mmu_notifier_unregister);
+
+static int __init mmu_notifier_init(void)
+{
+ return init_srcu_struct(&srcu);
+}
+
+module_init(mmu_notifier_init);
git.openpandora.org / pandora-kernel.git / blobdiff