From patchwork Wed Jul 10 09:31:16 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 13729128 Received: from mail-lf1-f54.google.com (mail-lf1-f54.google.com [209.85.167.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 66CA284D0D for ; Wed, 10 Jul 2024 09:33:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.54 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720604006; cv=none; b=QPRIfjiHA3Pcgh+3NBgfdMpj9kwNC9FJkj2SYdx4g9vzeod4ochEHkymUdZAMoXNdknSh6t9YHgLqd9h9nUGOgZAOhtOHgLcs4FW/qLWEjBBAPNGZVk1f/ufd4d3TTTgdaREJvQW0p3dXFAaop62ZjHlYbNmPDDNZnc4QZXRP9c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720604006; c=relaxed/simple; bh=N+dZVEJ8nJMAFRXQCYmz3Dujgc4/GF2zc1NIyCFnmmw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=PsIvt/Yqn6v9cvARCxiAITF9FUdjTTbnLBl0ylkDEbovlPLZ5ZeOfKl9E2PvRU1X85LPJvmSKNaJWgrKBjafZGd8um6bfctBai/isUO7/XQz0+Z3QaQ0zfA3YuJE+/WDVntyRKdpMf79YaLvMr8bB25fScCENyoFac0kpKYVV48= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch; spf=none smtp.mailfrom=ffwll.ch; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b=RAaMU1DY; arc=none smtp.client-ip=209.85.167.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ffwll.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="RAaMU1DY" Received: by mail-lf1-f54.google.com with SMTP id 2adb3069b0e04-52ea84b6131so633594e87.3 for ; Wed, 10 Jul 2024 02:33:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; t=1720604001; x=1721208801; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=GTHGZWFFIG2y8znG1jvML///poV3IrhnVzz1kC5uonU=; b=RAaMU1DYxFpW2zRlE5w7W+C+/UqEpGSH9cOtRdWVZgc6zye8fn/QrPGJpmL3HgEUKL P2hcjvLMXAWmBEhrnWxB9IAvtSs6m/2fYc9cbRX+/AG9D0SAWkkbGZCd6VcC6wOQ5mWm jfAULBDrQEQbxYuP1ROSZvHJL+QR2BJsxjDGI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720604001; x=1721208801; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=GTHGZWFFIG2y8znG1jvML///poV3IrhnVzz1kC5uonU=; b=TWOTwRQWOCFWmVCE6zm2P5w6Mb1iamSBZ/+PJHGXT5zaONP5lAmhs1pHZQMd9lalOR X+Htr11mqRUUJgJQirwSYvg//XfrvLjQOpwraqXMN/4zqnavgkdH2XKMBmnDHWnisiUY jjg1lYXVj9KaKcJOHNPUAcFYETNXYJ1wfXfCeytNwly1SKuatBKeke/OdMBBiiYMeLOf mgjuwIJH2O0/Dt67ppbvyOMhwXSe9StQqKhKkSJOIcU2jpOgk6uXEO5G3HuLVtUSE01J tSO29U/Nn/AM/DdXglzlgYkR8CtFM0Hly6RRkAzsop76f8yPh6wSgNEY1njtim/dVapQ 381g== X-Forwarded-Encrypted: i=1; AJvYcCVTR1/G9TWCOK6UjG07TA51DA19zICboOy+3RDxHy4O62qW8w2iEV2UDnGo1t6n7EZnW8LIXuYlI474z5V+T0LtUSqjPxXBS5VasuI= X-Gm-Message-State: AOJu0YzJZrGhb6HIZCU0ONi8+9Tb6u0A0xrqNxtnf+H7q6V95fg/FogB KibfFjJ1dg7FQk+xi4Z2YHTKw697tgaFvtQ28S8HCr88yK0Z5nywYyiT39H80Y0= X-Google-Smtp-Source: AGHT+IE53obXe9iAhMtu+VAErcsSEkowso2ZAWhhq6KbgW5hVFggamUEZCMm4iphO7D+n2JaklYQbA== X-Received: by 2002:a05:6512:10d2:b0:52e:9b18:9a7f with SMTP id 2adb3069b0e04-52eb9993c36mr3246261e87.2.1720604001546; Wed, 10 Jul 2024 02:33:21 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4266f6f5a27sm73448935e9.23.2024.07.10.02.33.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jul 2024 02:33:20 -0700 (PDT) From: Daniel Vetter To: DRI Development , LKML Cc: Intel Graphics Development , Daniel Vetter , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Subject: [PATCH 1/2] drm: Add might_fault to drm_modeset_lock priming Date: Wed, 10 Jul 2024 11:31:16 +0200 Message-ID: <20240710093120.732208-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 We already teach lockdep that dma_resv nests within drm_modeset_lock, but there's a lot more: All drm kms ioctl rely on being able to put/get_user while holding modeset locks, so we really need a might_fault in there too to complete the picture. Add it. Motivated by a syzbot report that blew up on bcachefs doing an unconditional console_lock way deep in the locking hierarchy, and lockdep only noticing the depency loop in a drm ioctl instead of much earlier. This annotation will make sure such issues have a much harder time escaping. References: https://lore.kernel.org/dri-devel/00000000000073db8b061cd43496@google.com/ Signed-off-by: Daniel Vetter Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: Sumit Semwal Cc: "Christian König" Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Christian König . --- drivers/gpu/drm/drm_mode_config.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index 568972258222..37d2e0a4ef4b 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -456,6 +456,8 @@ int drmm_mode_config_init(struct drm_device *dev) if (ret == -EDEADLK) ret = drm_modeset_backoff(&modeset_ctx); + might_fault(); + ww_acquire_init(&resv_ctx, &reservation_ww_class); ret = dma_resv_lock(&resv, &resv_ctx); if (ret == -EDEADLK)