From 9e3fc1d65d4e8cf302e289847ab165ad9358fdb2 Mon Sep 17 00:00:00 2001 From: Matthew Auld Date: Fri, 2 Feb 2024 17:14:36 +0000 Subject: [PATCH] drm/xe/vm: don't ignore error when in_kthread MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If GUP fails and we are in_kthread, we can have pinned = 0 and ret = 0. If that happens we call sg_alloc_append_table_from_pages() with n_pages = 0, which is not well behaved and can trigger: kernel BUG at include/linux/scatterlist.h:115! depending on if the pages array happens to be zeroed or not. Even if we don't hit that it crashes later when trying to dma_map the returned table. Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") Signed-off-by: Matthew Auld Cc: Thomas Hellström Cc: Matthew Brost Reviewed-by: Matthew Brost Link: https://patchwork.freedesktop.org/patch/msgid/20240202171435.427630-2-matthew.auld@intel.com (cherry picked from commit 8087199cd5951c1eba26003b3e4296dbb2110adf) Signed-off-by: Thomas Hellström --- drivers/gpu/drm/xe/xe_vm.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c index 99f151d73154..a9df89413155 100644 --- a/drivers/gpu/drm/xe/xe_vm.c +++ b/drivers/gpu/drm/xe/xe_vm.c @@ -114,11 +114,8 @@ retry: num_pages - pinned, read_only ? 0 : FOLL_WRITE, &pages[pinned]); - if (ret < 0) { - if (in_kthread) - ret = 0; + if (ret < 0) break; - } pinned += ret; ret = 0;