-----Original Message----- From: Auld, Matthew matthew.auld@intel.com Sent: Tuesday, September 10, 2024 6:42 PM To: intel-xe@lists.freedesktop.org Cc: Ghimiray, Himal Prasad himal.prasad.ghimiray@intel.com; Upadhyay, Tejas tejas.upadhyay@intel.com; Thomas Hellström thomas.hellstrom@linux.intel.com; stable@vger.kernel.org Subject: [PATCH 1/4] drm/xe/client: fix deadlock in show_meminfo()
There is a real deadlock as well as sleeping in atomic() bug in here, if the bo put happens to be the last ref, since bo destruction wants to grab the same spinlock and sleeping locks. Fix that by dropping the ref using xe_bo_put_deferred(), and moving the final commit outside of the lock. Dropping the lock around the put is tricky since the bo can go out of scope and delete itself from the list, making it difficult to navigate to the next list entry.
Fixes: 0845233388f8 ("drm/xe: Implement fdinfo memory stats printing") Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2727 Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Himal Prasad Ghimiray himal.prasad.ghimiray@intel.com Cc: Tejas Upadhyay tejas.upadhyay@intel.com Cc: "Thomas Hellström" thomas.hellstrom@linux.intel.com Cc: stable@vger.kernel.org # v6.8+
drivers/gpu/drm/xe/xe_drm_client.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/xe/xe_drm_client.c b/drivers/gpu/drm/xe/xe_drm_client.c index e64f4b645e2e..badfa045ead8 100644 --- a/drivers/gpu/drm/xe/xe_drm_client.c +++ b/drivers/gpu/drm/xe/xe_drm_client.c @@ -196,6 +196,7 @@ static void show_meminfo(struct drm_printer *p, struct drm_file *file) struct xe_drm_client *client; struct drm_gem_object *obj; struct xe_bo *bo;
- LLIST_HEAD(deferred); unsigned int id; u32 mem_type;
@@ -215,11 +216,14 @@ static void show_meminfo(struct drm_printer *p, struct drm_file *file) list_for_each_entry(bo, &client->bos_list, client_link) { if (!kref_get_unless_zero(&bo->ttm.base.refcount)) continue;
- bo_meminfo(bo, stats);
xe_bo_put(bo);
xe_bo_put_deferred(bo, &deferred);} spin_unlock(&client->bos_lock);
xe_bo_put_commit(&deferred);
Reviewed-by: Tejas Upadhyay tejas.upadhyay@intel.com
Thanks, Tejas
for (mem_type = XE_PL_SYSTEM; mem_type < TTM_NUM_MEM_TYPES; ++mem_type) { if (!xe_mem_type_to_name[mem_type]) continue; -- 2.46.0