The patch titled
Subject: mm/hmm: HMM should have a callback before MM is destroyed
has been added to the -mm tree. Its filename is
mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed.patch
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------------------------------------------------------
From: Ralph Campbell <rcampbell@xxxxxxxxxx>
Subject: 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/20180315183700.3843-4-jglisse@xxxxxxxxxx
Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Evgeny Baskakov <ebaskakov@xxxxxxxxxx>
Cc: Mark Hairgrove <mhairgrove@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN include/linux/hmm.h~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed include/linux/hmm.h
--- a/include/linux/hmm.h~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed
+++ a/include/linux/hmm.h
@@ -218,6 +218,16 @@ enum hmm_update_type {
* @update: callback to update range on a device
*/
struct hmm_mirror_ops {
+ /* release() - release hmm_mirror
+ *
+ * @mirror: pointer to struct hmm_mirror
+ *
+ * This is called when the mm_struct is being released.
+ * The callback should make sure no references to the mirror occur
+ * after the callback returns.
+ */
+ void (*release)(struct hmm_mirror *mirror);
+
/* sync_cpu_device_pagetables() - synchronize page tables
*
* @mirror: pointer to struct hmm_mirror
diff -puN mm/hmm.c~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed mm/hmm.c
--- a/mm/hmm.c~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed
+++ a/mm/hmm.c
@@ -160,6 +160,23 @@ static void hmm_invalidate_range(struct
up_read(&hmm->mirrors_sem);
}
+static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ struct hmm *hmm = mm->hmm;
+ struct hmm_mirror *mirror;
+ struct hmm_mirror *mirror_next;
+
+ VM_BUG_ON(!hmm);
+
+ down_write(&hmm->mirrors_sem);
+ list_for_each_entry_safe(mirror, mirror_next, &hmm->mirrors, list) {
+ list_del_init(&mirror->list);
+ if (mirror->ops->release)
+ mirror->ops->release(mirror);
+ }
+ up_write(&hmm->mirrors_sem);
+}
+
static void hmm_invalidate_range_start(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start,
@@ -185,6 +202,7 @@ static void hmm_invalidate_range_end(str
}
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 +248,7 @@ void hmm_mirror_unregister(struct hmm_mi
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);
_
Patches currently in -mm which might be from rcampbell@xxxxxxxxxx are
mm-hmm-documentation-editorial-update-to-hmm-documentation.patch
mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed.patch
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