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    SubjectRe: [RFC PATCH] drm/radeon: fixup locking inversion between mmap_sem and reservations
    op 08-10-13 16:33, Jerome Glisse schreef:
    > On Tue, Oct 08, 2013 at 04:14:40PM +0200, Maarten Lankhorst wrote:
    >> Allocate and copy all kernel memory before doing reservations. This prevents a locking
    >> inversion between mmap_sem and reservation_class, and allows us to drop the trylocking
    >> in ttm_bo_vm_fault without upsetting lockdep.
    >>
    >> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
    > I would say NAK. Current code only allocate temporary page in AGP case.
    > So AGP case is userspace -> temp page -> cs checker -> radeon ib.
    >
    > Non AGP is directly memcpy to radeon IB.
    >
    > Your patch allocate memory memcpy userspace to it and it will then be
    > memcpy to IB. Which means you introduce an extra memcpy in the process
    > not something we want.
    >
    Can we move up the call to radeon_ib_get then to be done before calling radeon_cs_parser_relocs?

    ~Maarten


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