This is a note to let you know that I've just added the patch titled
drm: Require __GFP_NOFAIL for the legacy drm_modeset_lock_all
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: drm-require-__gfp_nofail-for-the-legacy-drm_modeset_lock_all.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From d18d1a5ac811d12f7ebc1129230312b5f2c50cb8 Mon Sep 17 00:00:00 2001
From: Chris Wilson chris@chris-wilson.co.uk Date: Tue, 31 Oct 2017 11:55:35 +0000 Subject: drm: Require __GFP_NOFAIL for the legacy drm_modeset_lock_all MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
From: Chris Wilson chris@chris-wilson.co.uk
commit d18d1a5ac811d12f7ebc1129230312b5f2c50cb8 upstream.
To acquire all modeset locks requires a ww_ctx to be allocated. As this is the legacy path and the allocation small, to reduce the changes required (and complex untested error handling) to the legacy drivers, we simply assume that the allocation succeeds. At present, it relies on the too-small-to-fail rule, but syzbot found that by injecting a failure here we would hit the WARN. Document that this allocation must succeed with __GFP_NOFAIL.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Daniel Vetter daniel.vetter@ffwll.ch Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20171031115535.15166-1-chris@c... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/drm_modeset_lock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/gpu/drm/drm_modeset_lock.c +++ b/drivers/gpu/drm/drm_modeset_lock.c @@ -69,7 +69,7 @@ void drm_modeset_lock_all(struct drm_dev struct drm_modeset_acquire_ctx *ctx; int ret;
- ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | __GFP_NOFAIL); if (WARN_ON(!ctx)) return;
Patches currently in stable-queue which might be from chris@chris-wilson.co.uk are
queue-4.4/drm-require-__gfp_nofail-for-the-legacy-drm_modeset_lock_all.patch