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Subject[PATCH 3/3] Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks"
Date
From: Michal Hocko <mhocko@suse.com>

This reverts commit 5ff7091f5a2ca1b7b642ca0dbdede8f693a56926.

MMU_INVALIDATE_DOES_NOT_BLOCK flags was the only one used and it is no
longer needed since 93065ac753e4 ("mm, oom: distinguish blockable mode
for mmu notifiers"). We now have a full support for per range !blocking
behavior so we can drop the stop gap workaround which the per notifier
flag was used for.

Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
drivers/infiniband/hw/hfi1/mmu_rb.c | 1 -
drivers/iommu/amd_iommu_v2.c | 1 -
drivers/iommu/intel-svm.c | 1 -
drivers/misc/sgi-gru/grutlbpurge.c | 1 -
include/linux/mmu_notifier.h | 23 ---------------------
mm/mmu_notifier.c | 31 -----------------------------
virt/kvm/kvm_main.c | 1 -
7 files changed, 59 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/mmu_rb.c b/drivers/infiniband/hw/hfi1/mmu_rb.c
index e1c7996c018e..475b769e120c 100644
--- a/drivers/infiniband/hw/hfi1/mmu_rb.c
+++ b/drivers/infiniband/hw/hfi1/mmu_rb.c
@@ -77,7 +77,6 @@ static void do_remove(struct mmu_rb_handler *handler,
static void handle_remove(struct work_struct *work);

static const struct mmu_notifier_ops mn_opts = {
- .flags = MMU_INVALIDATE_DOES_NOT_BLOCK,
.invalidate_range_start = mmu_notifier_range_start,
};

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 58da65df03f5..fd552235bd13 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -427,7 +427,6 @@ static void mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
}

static const struct mmu_notifier_ops iommu_mn = {
- .flags = MMU_INVALIDATE_DOES_NOT_BLOCK,
.release = mn_release,
.clear_flush_young = mn_clear_flush_young,
.invalidate_range = mn_invalidate_range,
diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index 7d65aab36a96..e16ee247add8 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -292,7 +292,6 @@ static void intel_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
}

static const struct mmu_notifier_ops intel_mmuops = {
- .flags = MMU_INVALIDATE_DOES_NOT_BLOCK,
.release = intel_mm_release,
.change_pte = intel_change_pte,
.invalidate_range = intel_invalidate_range,
diff --git a/drivers/misc/sgi-gru/grutlbpurge.c b/drivers/misc/sgi-gru/grutlbpurge.c
index be28f05bfafa..03b49d52092e 100644
--- a/drivers/misc/sgi-gru/grutlbpurge.c
+++ b/drivers/misc/sgi-gru/grutlbpurge.c
@@ -261,7 +261,6 @@ static void gru_release(struct mmu_notifier *mn, struct mm_struct *mm)


static const struct mmu_notifier_ops gru_mmuops = {
- .flags = MMU_INVALIDATE_DOES_NOT_BLOCK,
.invalidate_range_start = gru_invalidate_range_start,
.invalidate_range_end = gru_invalidate_range_end,
.release = gru_release,
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 698e371aafe3..9893a6432adf 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -2,7 +2,6 @@
#ifndef _LINUX_MMU_NOTIFIER_H
#define _LINUX_MMU_NOTIFIER_H

-#include <linux/types.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/mm_types.h>
@@ -11,9 +10,6 @@
struct mmu_notifier;
struct mmu_notifier_ops;

-/* mmu_notifier_ops flags */
-#define MMU_INVALIDATE_DOES_NOT_BLOCK (0x01)
-
#ifdef CONFIG_MMU_NOTIFIER

/*
@@ -30,15 +26,6 @@ struct mmu_notifier_mm {
};

struct mmu_notifier_ops {
- /*
- * Flags to specify behavior of callbacks for this MMU notifier.
- * Used to determine which context an operation may be called.
- *
- * MMU_INVALIDATE_DOES_NOT_BLOCK: invalidate_range_* callbacks do not
- * block
- */
- int flags;
-
/*
* Called either by mmu_notifier_unregister or when the mm is
* being destroyed by exit_mmap, always before all pages are
@@ -183,10 +170,6 @@ struct mmu_notifier_ops {
* Note that this function might be called with just a sub-range
* of what was passed to invalidate_range_start()/end(), if
* called between those functions.
- *
- * If this callback cannot block, and invalidate_range_{start,end}
- * cannot block, mmu_notifier_ops.flags should have
- * MMU_INVALIDATE_DOES_NOT_BLOCK set.
*/
void (*invalidate_range)(struct mmu_notifier *mn, struct mm_struct *mm,
unsigned long start, unsigned long end);
@@ -241,7 +224,6 @@ extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
bool only_end);
extern void __mmu_notifier_invalidate_range(struct mm_struct *mm,
unsigned long start, unsigned long end);
-extern bool mm_has_blockable_invalidate_notifiers(struct mm_struct *mm);

static inline void mmu_notifier_release(struct mm_struct *mm)
{
@@ -495,11 +477,6 @@ static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
{
}

-static inline bool mm_has_blockable_invalidate_notifiers(struct mm_struct *mm)
-{
- return false;
-}
-
static inline void mmu_notifier_mm_init(struct mm_struct *mm)
{
}
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 82bb1a939c0e..5119ff846769 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -247,37 +247,6 @@ void __mmu_notifier_invalidate_range(struct mm_struct *mm,
}
EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range);

-/*
- * Must be called while holding mm->mmap_sem for either read or write.
- * The result is guaranteed to be valid until mm->mmap_sem is dropped.
- */
-bool mm_has_blockable_invalidate_notifiers(struct mm_struct *mm)
-{
- struct mmu_notifier *mn;
- int id;
- bool ret = false;
-
- WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem));
-
- if (!mm_has_notifiers(mm))
- return ret;
-
- id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
- if (!mn->ops->invalidate_range &&
- !mn->ops->invalidate_range_start &&
- !mn->ops->invalidate_range_end)
- continue;
-
- if (!(mn->ops->flags & MMU_INVALIDATE_DOES_NOT_BLOCK)) {
- ret = true;
- break;
- }
- }
- srcu_read_unlock(&srcu, id);
- return ret;
-}
-
static int do_mmu_notifier_register(struct mmu_notifier *mn,
struct mm_struct *mm,
int take_mmap_sem)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f986e31fa68c..636462edc7ca 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -499,7 +499,6 @@ static void kvm_mmu_notifier_release(struct mmu_notifier *mn,
}

static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
- .flags = MMU_INVALIDATE_DOES_NOT_BLOCK,
.invalidate_range_start = kvm_mmu_notifier_invalidate_range_start,
.invalidate_range_end = kvm_mmu_notifier_invalidate_range_end,
.clear_flush_young = kvm_mmu_notifier_clear_flush_young,
--
2.18.0
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