From: Chris Wilson Date: Tue, 31 Oct 2017 11:55:35 +0000 (+0000) Subject: drm: Require __GFP_NOFAIL for the legacy drm_modeset_lock_all X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=d18d1a5ac811d12f7ebc1129230312b5f2c50cb8;p=openwrt%2Fstaging%2Fblogic.git drm: Require __GFP_NOFAIL for the legacy drm_modeset_lock_all 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 Cc: Daniel Vetter Reported-by: syzbot Signed-off-by: Daniel Vetter Reviewed-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20171031115535.15166-1-chris@chris-wilson.co.uk --- diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c index e123497da0ca..963e23db0fe7 100644 --- a/drivers/gpu/drm/drm_modeset_lock.c +++ b/drivers/gpu/drm/drm_modeset_lock.c @@ -93,7 +93,7 @@ void drm_modeset_lock_all(struct drm_device *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;