From: Michal Hocko <[email protected]>

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 <[email protected]>
Signed-off-by: Michal Hocko <[email protected]>
---
 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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