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    Subject[PATCH 5.10 063/530] drm/panfrost: Dont try to map pages that are already mapped
    Date
    From: Boris Brezillon <boris.brezillon@collabora.com>

    commit f45da8204ff1707c529a8769f5467ff16f504b26 upstream.

    We allocate 2MB chunks at a time, so it might appear that a page fault
    has already been handled by a previous page fault when we reach
    panfrost_mmu_map_fault_addr(). Bail out in that case to avoid mapping the
    same area twice.

    Cc: <stable@vger.kernel.org>
    Fixes: 187d2929206e ("drm/panfrost: Add support for GPU heap allocations")
    Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
    Reviewed-by: Steven Price <steven.price@arm.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20210205111757.585248-3-boris.brezillon@collabora.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/gpu/drm/panfrost/panfrost_mmu.c | 9 ++++++++-
    1 file changed, 8 insertions(+), 1 deletion(-)

    --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
    +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
    @@ -495,8 +495,14 @@ static int panfrost_mmu_map_fault_addr(s
    }
    bo->base.pages = pages;
    bo->base.pages_use_count = 1;
    - } else
    + } else {
    pages = bo->base.pages;
    + if (pages[page_offset]) {
    + /* Pages are already mapped, bail out. */
    + mutex_unlock(&bo->base.pages_lock);
    + goto out;
    + }
    + }

    mapping = bo->base.base.filp->f_mapping;
    mapping_set_unevictable(mapping);
    @@ -529,6 +535,7 @@ static int panfrost_mmu_map_fault_addr(s

    dev_dbg(pfdev->dev, "mapped page fault @ AS%d %llx", as, addr);

    +out:
    panfrost_gem_mapping_put(bomapping);

    return 0;

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