From b5c55015d4164a0f206bcdcf2985da948b3c7837 Mon Sep 17 00:00:00 2001 From: Matthew Auld Date: Thu, 25 Jun 2026 16:20:56 +0100 Subject: [PATCH] drm/xe: fix NPD in bo_meminfo() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When a buffer object is purged, its ttm.resource is set to NULL via the TTM pipeline gutting flow. However, the BO remains in the client's object list until userspace explicitly closes the GEM handle. If memory stats are queried during this time, accessing bo->ttm.resource->mem_type will result in a NULL pointer dereference. Fix this by safely skipping purged BOs in bo_meminfo, as they no longer consume any memory. User is getting NPD on device resume, and possible theory is that in bo_move(), if we need to evict something to SYSTEM to save the CCS state, but the BO is marked as dontneed, this won't trigger a move but will nuke the pages, leaving us with a NULL bo resource. And the meminfo() doesn't look ready to handle a NULL resource. v2 (Sashiko): - There could potentially be other cases where we might end up with a NULL resource, so make this a general NULL check for now. Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/8419 Fixes: ad9843aac91a ("drm/xe/madvise: Implement purgeable buffer object support") Assisted-by: Copilot:gemini-3.1-pro-preview Reported-by: Matthew Schwartz Signed-off-by: Matthew Auld Cc: Thomas Hellström Cc: Matthew Brost Cc: Arvind Yadav Reviewed-by: Matthew Brost Tested-by: Matthew Schwartz Link: https://patch.msgid.link/20260625152054.450125-6-matthew.auld@intel.com (cherry picked from commit c9a8e7daa0afe3161111e27fd92176e608c7f186) Signed-off-by: Thomas Hellström --- drivers/gpu/drm/xe/xe_drm_client.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/xe/xe_drm_client.c b/drivers/gpu/drm/xe/xe_drm_client.c index 84b66147bf49..81020b4b344e 100644 --- a/drivers/gpu/drm/xe/xe_drm_client.c +++ b/drivers/gpu/drm/xe/xe_drm_client.c @@ -168,10 +168,20 @@ static void bo_meminfo(struct xe_bo *bo, struct drm_memory_stats stats[TTM_NUM_MEM_TYPES]) { u64 sz = xe_bo_size(bo); - u32 mem_type = bo->ttm.resource->mem_type; + u32 mem_type; xe_bo_assert_held(bo); + /* + * The resource can be NULL if the BO has been purged, plus maybe some + * other cases. Either way there shouldn't be any memory to account for, + * or a current resource to account this against, so skip for now. + */ + if (!bo->ttm.resource) + return; + + mem_type = bo->ttm.resource->mem_type; + if (drm_gem_object_is_shared_for_memory_stats(&bo->ttm.base)) stats[mem_type].shared += sz; else