From: Zack Rusin Date: Tue, 5 May 2026 22:22:24 +0000 (-0400) Subject: drm/vmwgfx: clamp dirty-page range with min, not max X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f47d542d5912f236273399d7139b522f6950e2e4;p=thirdparty%2Flinux.git drm/vmwgfx: clamp dirty-page range with min, not max vmw_bo_dirty_transfer_to_res() and vmw_bo_dirty_clear() compute the intersection of a resource's page range with the BO's tracked dirty range, but clamp res_end against dirty->end with max() instead of min(). When dirty->end exceeds the resource end, the loop walks past the resource's pages, calls vmw_resource_dirty_update() for ranges owned by other resources sharing the same backing MOB and clears their pending dirty bits via bitmap_clear(). The result is silent loss of writeback for unrelated resources whenever two resources share a MOB. Use min() in both functions so the loop is bounded to the intersection of the resource and dirty ranges. Fixes: b7468b15d271 ("drm/vmwgfx: Implement an infrastructure for write-coherent resources") Fixes: 965544150d1c ("drm/vmwgfx: Refactor cursor handling") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4.7 Signed-off-by: Zack Rusin Reviewed-by: Ian Forbes Link: https://patch.msgid.link/20260505222728.519626-4-zack.rusin@broadcom.com --- diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c index 45561bc1c9ef..8ab88f388652 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c @@ -311,7 +311,7 @@ void vmw_bo_dirty_transfer_to_res(struct vmw_resource *res) return; cur = max(res_start, dirty->start); - res_end = max(res_end, dirty->end); + res_end = min(res_end, dirty->end); while (cur < res_end) { unsigned long num; @@ -347,7 +347,7 @@ void vmw_bo_dirty_clear(struct vmw_bo *vbo) return; cur = max(res_start, dirty->start); - res_end = max(res_end, dirty->end); + res_end = min(res_end, dirty->end); while (cur < res_end) { unsigned long num;