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    SubjectRe: [PATCH 5.16 0702/1039] drm/amdgpu: Dont inherit GEM object VMAs in child process
    On Tue, Jan 25, 2022 at 09:16:17AM +0100, Greg Kroah-Hartman wrote:
    > On Tue, Jan 25, 2022 at 08:26:20AM +0100, Christian König wrote:
    > > Hi Greg,
    > >
    > > Am 24.01.22 um 19:41 schrieb Greg Kroah-Hartman:
    > > > From: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
    > > >
    > > > [ Upstream commit fbcdbfde87509d523132b59f661a355c731139d0 ]
    > > >
    > > > 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>
    > > > Signed-off-by: Sasha Levin <sashal@kernel.org>
    > >
    > > Please drop this patch from all stable versions since it was reverted from
    > > upstream later on.
    >
    > The revert comes later in the patch series, so all should be ok :)

    Looks like Sasha dropped this, so I'll go drop the revert as well.

    thanks,

    greg k-h

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