mm/hmm: invalidate device page table at start of invalidation

Invalidate device page table at start of invalidation and invalidate in
progress CPU page table snapshooting at both start and end of any
invalidation.

This is helpful when device need to dirty page because the device page
table report the page as dirty.  Dirtying page must happen in the start
mmu notifier callback and not in the end one.

Link: http://lkml.kernel.org/r/20181019160442.18723-7-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hmm.c b/mm/hmm.c
index b4e9afdc2181d4b634d33cb6fea4700349908afd..90c34f3d1243aa5ec18970ec7aac095d8f657d32 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -43,7 +43,6 @@ static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
  *
  * @mm: mm struct this HMM struct is bound to
  * @lock: lock protecting ranges list
- * @sequence: we track updates to the CPU page table with a sequence number
  * @ranges: list of range being snapshotted
  * @mirrors: list of mirrors for this mm
  * @mmu_notifier: mmu notifier to track updates to CPU page table
@@ -52,7 +51,6 @@ static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
 struct hmm {
        struct mm_struct        *mm;
        spinlock_t              lock;
-       atomic_t                sequence;
        struct list_head        ranges;
        struct list_head        mirrors;
        struct mmu_notifier     mmu_notifier;
@@ -85,7 +83,6 @@ static struct hmm *hmm_register(struct mm_struct *mm)
                return NULL;
        INIT_LIST_HEAD(&hmm->mirrors);
        init_rwsem(&hmm->mirrors_sem);
-       atomic_set(&hmm->sequence, 0);
        hmm->mmu_notifier.ops = NULL;
        INIT_LIST_HEAD(&hmm->ranges);
        spin_lock_init(&hmm->lock);
@@ -126,7 +123,7 @@ void hmm_mm_destroy(struct mm_struct *mm)
        kfree(mm->hmm);
 }
 
-static int hmm_invalidate_range(struct hmm *hmm,
+static int hmm_invalidate_range(struct hmm *hmm, bool device,
                                const struct hmm_update *update)
 {
        struct hmm_mirror *mirror;
@@ -147,6 +144,9 @@ static int hmm_invalidate_range(struct hmm *hmm,
        }
        spin_unlock(&hmm->lock);
 
+       if (!device)
+               return 0;
+
        down_read(&hmm->mirrors_sem);
        list_for_each_entry(mirror, &hmm->mirrors, list) {
                int ret;
@@ -189,18 +189,21 @@ static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 }
 
 static int hmm_invalidate_range_start(struct mmu_notifier *mn,
-                                      struct mm_struct *mm,
-                                      unsigned long start,
-                                      unsigned long end,
-                                      bool blockable)
+                                     struct mm_struct *mm,
+                                     unsigned long start,
+                                     unsigned long end,
+                                     bool blockable)
 {
+       struct hmm_update update;
        struct hmm *hmm = mm->hmm;
 
        VM_BUG_ON(!hmm);
 
-       atomic_inc(&hmm->sequence);
-
-       return 0;
+       update.start = start;
+       update.end = end;
+       update.event = HMM_UPDATE_INVALIDATE;
+       update.blockable = blockable;
+       return hmm_invalidate_range(hmm, true, &update);
 }
 
 static void hmm_invalidate_range_end(struct mmu_notifier *mn,
@@ -217,7 +220,7 @@ static void hmm_invalidate_range_end(struct mmu_notifier *mn,
        update.end = end;
        update.event = HMM_UPDATE_INVALIDATE;
        update.blockable = true;
-       hmm_invalidate_range(hmm, &update);
+       hmm_invalidate_range(hmm, false, &update);
 }
 
 static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {