On 17/07/14 17:12, Jerome Glisse wrote:
On Thu, Jul 17, 2014 at 04:57:58PM +0300, Oded Gabbay wrote:
Forgot to add mm mailing list. Sorry.
This patch enables the amdkfd driver to retrieve the kfd_process
object from the process's mm_struct. This is needed because kfd_process
lifespan is bound to the process's mm_struct lifespan.
When amdkfd is notified about an mm_struct tear-down, it checks if the
kfd_process pointer is valid. If so, it releases the kfd_process object
and all relevant resources.
In v3 of the patchset I will update the binding to match the final discussions
on [PATCH 1/8] mmput: use notifier chain to call subsystem exit handler.
In the meantime, I'm going to try and see if I can drop the kfd_process
in mm_struct and remove the use of the new notification chain in mmput.
Instead, I will try to use the mmu release notifier.
So the mmput notifier chain will not happen. I did a patch with call_srcu
and adding couple more helper to mmu_notifier. I will send that today for
review.
That being said, adding a device driver specific to mm_struct will most
likely be a big no. I am myself gonna remove hmm from mm_struct as people
are reluctant to see such change.
Cheers,
Jérôme
Yes, I followed that email thread and you can see that in the commit message I
referred to it (saying that in v3 of the patchset I'm also going to use
mmu_notifier). I will take your patch once you publish it and use it to change
amdkfd behavior.
Oded
Signed-off-by: Oded Gabbay <oded.gabbay@xxxxxxx>
---
include/linux/mm_types.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 678097c..ff71496 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -20,6 +20,10 @@
struct hmm;
#endif
+#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
+struct kfd_process;
+#endif
+
#ifndef AT_VECTOR_SIZE_ARCH
#define AT_VECTOR_SIZE_ARCH 0
#endif
@@ -439,6 +443,16 @@ struct mm_struct {
*/
struct hmm *hmm;
#endif
+#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
+ /*
+ * kfd always register an mmu_notifier we rely on mmu notifier to keep
+ * refcount on mm struct as well as forbiding registering kfd on a
+ * dying mm
+ *
+ * This field is set with mmap_sem old in write mode.
+ */
+ struct kfd_process *kfd_process;
+#endif
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
--
1.9.1
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