[PATCH 5.11 065/601] drm/panfrost: Dont try to map pages that are already mapped

Greg Kroah-Hartman
2021-05-12T17:02:22Z

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
@@ -488,8 +488,14 @@ 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);
@@ -522,6 +528,7 @@ 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;