[PATCH] drm/amdkfd: drop process ref count when xnack disable

[Kim, Jonathan]

[AMD Official Use Only]

We were seeing process leaks on a couple of machines running certain tests that triggered vm faults on purpose.
I think svm_range_restore_pages gets called unconditionally on vm fault handling (unless the retry interrupt payload bit is supposed to be clear with xnack off)?

Either way, this patch prevents the process leaks we seeing and is also:
Reviewed-by: Jonathan Kim <jonathan.kim at amd.com>

Thanks,

Jon


From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of philip yang
Sent: Wednesday, September 1, 2021 7:30 AM
To: Sierra Guiza, Alejandro (Alex) <Alex.Sierra at amd.com>; amd-gfx at lists.freedesktop.org
Subject: Re: [PATCH] drm/amdkfd: drop process ref count when xnack disable

[CAUTION: External Email]


On 2021-08-31 10:41 p.m., Alex Sierra wrote:

During svm restore pages interrupt handler, kfd_process ref count was

never dropped when xnack was disabled. Therefore, the object was never

released.

Good catch, but if xnack is off, we should not get here to recover fault.

The fix looks good to me.

Reviewed-by: Philip Yang <philip.yang at amd.com><mailto:philip.yang at amd.com>



Signed-off-by: Alex Sierra <alex.sierra at amd.com><mailto:alex.sierra at amd.com>

---

 drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 3 ++-

 1 file changed, 2 insertions(+), 1 deletion(-)



diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c

index 8f9b5b53dab5..110c46cd7fac 100644

--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c

+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c

@@ -2484,7 +2484,8 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,

         }

         if (!p->xnack_enabled) {

                pr_debug("XNACK not enabled for pasid 0x%x\n", pasid);

-               return -EFAULT;

+               r = -EFAULT;

+               goto out;

         }

         svms = &p->svms;


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