From 9bd7ff293fc84792514aeafa06c5a17f05cb5f4b Mon Sep 17 00:00:00 2001 From: Matthew Auld Date: Wed, 11 Sep 2024 16:55:27 +0100 Subject: [PATCH] drm/xe/client: fix deadlock in show_meminfo() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Cc: Himal Prasad Ghimiray Cc: Tejas Upadhyay Cc: "Thomas Hellström" Cc: # v6.8+ Reviewed-by: Matthew Brost Reviewed-by: Tejas Upadhyay Link: https://patchwork.freedesktop.org/patch/msgid/20240911155527.178910-5-matthew.auld@intel.com (cherry picked from commit 0083b8e6f11d7662283a267d4ce7c966812ffd8a) Signed-off-by: Rodrigo Vivi --- 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 7ddd59908334..ec141357480f 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); + for (mem_type = XE_PL_SYSTEM; mem_type < TTM_NUM_MEM_TYPES; ++mem_type) { if (!xe_mem_type_to_name[mem_type]) continue;