From 6a7b3fd5ad7101616e5b8f30bbe0feb202e55ab6 Mon Sep 17 00:00:00 2001
From: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Date: Fri, 26 Nov 2021 15:15:04 -0500
Subject: drm/amdgpu: Don't inherit GEM object VMAs in child process
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Git-commit: fbcdbfde87509d523132b59f661a355c731139d0
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
When an application having open file access to a node forks, its shared
mappings also get reflected in the address space of child process even
though it cannot access them with the object permissions applied. With the
existing permission checks on the gem objects, it might be reasonable to
also create the VMAs with VM_DONTCOPY flag so a user space application
doesn't need to explicitly call the madvise(addr, len, MADV_DONTFORK)
system call to prevent the pages in the mapped range to appear in the
address space of the child process. It also prevents the memory leaks
due to additional reference counts on the mapped BOs in the child
process that prevented freeing the memory in the parent for which we had
worked around earlier in the user space inside the thunk library.
Additionally, we faced this issue when using CRIU to checkpoint restore
an application that had such inherited mappings in the child which
confuse CRIU when it mmaps on restore. Having this flag set for the
render node VMAs helps. VMAs mapped via KFD already take care of this so
this is needed only for the render nodes.
To limit the impact of the change to user space consumers such as OpenGL
etc, limit it to KFD BOs only.
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: David Yat Sin <david.yatsin@amd.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index c0d8f40a5b45..9a6507af1670 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -264,6 +264,9 @@ static int amdgpu_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_str
!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
vma->vm_flags &= ~VM_MAYWRITE;
+ if (bo->kfd_bo)
+ vma->vm_flags |= VM_DONTCOPY;
+
return drm_gem_ttm_mmap(obj, vma);
}
--
2.38.1