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authorJason Gunthorpe <jgg@mellanox.com>2019-05-23 10:36:46 -0300
committerJason Gunthorpe <jgg@mellanox.com>2019-06-10 10:10:33 -0300
commitc8a53b2db0aec40d8b217936e1b7f3d840c50390 (patch)
treeea375fb462731dce8200eef3b650cd9acab2f1dd /mm/hmm.c
parente36acfe6c86d13eec62321e1e86a1ce287e52e7d (diff)
mm/hmm: Hold a mmgrab from hmm to mm
So long as a struct hmm pointer exists, so should the struct mm it is linked too. Hold the mmgrab() as soon as a hmm is created, and mmdrop() it once the hmm refcount goes to zero. Since mmdrop() (ie a 0 kref on struct mm) is now impossible with a !NULL mm->hmm delete the hmm_hmm_destroy(). Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Philip Yang <Philip.Yang@amd.com>
Diffstat (limited to 'mm/hmm.c')
-rw-r--r--mm/hmm.c22
1 files changed, 4 insertions, 18 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
index 22a97ada108b..080b17a2e87e 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -20,6 +20,7 @@
#include <linux/swapops.h>
#include <linux/hugetlb.h>
#include <linux/memremap.h>
+#include <linux/sched/mm.h>
#include <linux/jump_label.h>
#include <linux/dma-mapping.h>
#include <linux/mmu_notifier.h>
@@ -73,6 +74,7 @@ static struct hmm *hmm_get_or_create(struct mm_struct *mm)
hmm->notifiers = 0;
hmm->dead = false;
hmm->mm = mm;
+ mmgrab(hmm->mm);
spin_lock(&mm->page_table_lock);
if (!mm->hmm)
@@ -100,6 +102,7 @@ error_mm:
mm->hmm = NULL;
spin_unlock(&mm->page_table_lock);
error:
+ mmdrop(hmm->mm);
kfree(hmm);
return NULL;
}
@@ -121,6 +124,7 @@ static void hmm_free(struct kref *kref)
mm->hmm = NULL;
spin_unlock(&mm->page_table_lock);
+ mmdrop(hmm->mm);
mmu_notifier_call_srcu(&hmm->rcu, hmm_free_rcu);
}
@@ -129,24 +133,6 @@ static inline void hmm_put(struct hmm *hmm)
kref_put(&hmm->kref, hmm_free);
}
-void hmm_mm_destroy(struct mm_struct *mm)
-{
- struct hmm *hmm;
-
- spin_lock(&mm->page_table_lock);
- hmm = mm_get_hmm(mm);
- mm->hmm = NULL;
- if (hmm) {
- hmm->mm = NULL;
- hmm->dead = true;
- spin_unlock(&mm->page_table_lock);
- hmm_put(hmm);
- return;
- }
-
- spin_unlock(&mm->page_table_lock);
-}
-
static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);