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authorRalph Campbell <rcampbell@nvidia.com>2018-04-10 16:28:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-11 10:28:30 -0700
commite1401513c6b5efec59678a4d4e9f90957684b7e3 (patch)
tree3c3d5bd62643829a0f37155780161acbe5c290ed /mm
parentb28b08de436a638c82d0cf3dcdbdbad055baf1fc (diff)
downloadlinux-e1401513c6b5efec59678a4d4e9f90957684b7e3.tar.bz2
mm/hmm: HMM should have a callback before MM is destroyed
hmm_mirror_register() registers a callback for when the CPU pagetable is modified. Normally, the device driver will call hmm_mirror_unregister() when the process using the device is finished. However, if the process exits uncleanly, the struct_mm can be destroyed with no warning to the device driver. Link: http://lkml.kernel.org/r/20180323005527.758-4-jglisse@redhat.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Evgeny Baskakov <ebaskakov@nvidia.com> Cc: Mark Hairgrove <mhairgrove@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/hmm.c29
1 files changed, 28 insertions, 1 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
index 320545b98ff5..8116727766f7 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -160,6 +160,32 @@ static void hmm_invalidate_range(struct hmm *hmm,
up_read(&hmm->mirrors_sem);
}
+static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ struct hmm_mirror *mirror;
+ struct hmm *hmm = mm->hmm;
+
+ down_write(&hmm->mirrors_sem);
+ mirror = list_first_entry_or_null(&hmm->mirrors, struct hmm_mirror,
+ list);
+ while (mirror) {
+ list_del_init(&mirror->list);
+ if (mirror->ops->release) {
+ /*
+ * Drop mirrors_sem so callback can wait on any pending
+ * work that might itself trigger mmu_notifier callback
+ * and thus would deadlock with us.
+ */
+ up_write(&hmm->mirrors_sem);
+ mirror->ops->release(mirror);
+ down_write(&hmm->mirrors_sem);
+ }
+ mirror = list_first_entry_or_null(&hmm->mirrors,
+ struct hmm_mirror, list);
+ }
+ up_write(&hmm->mirrors_sem);
+}
+
static void hmm_invalidate_range_start(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start,
@@ -185,6 +211,7 @@ static void hmm_invalidate_range_end(struct mmu_notifier *mn,
}
static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
+ .release = hmm_release,
.invalidate_range_start = hmm_invalidate_range_start,
.invalidate_range_end = hmm_invalidate_range_end,
};
@@ -230,7 +257,7 @@ void hmm_mirror_unregister(struct hmm_mirror *mirror)
struct hmm *hmm = mirror->hmm;
down_write(&hmm->mirrors_sem);
- list_del(&mirror->list);
+ list_del_init(&mirror->list);
up_write(&hmm->mirrors_sem);
}
EXPORT_SYMBOL(hmm_mirror_unregister);