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: 13729126 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6023DC3DA4A for ; Wed, 10 Jul 2024 09:33:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BF9D610E1C6; Wed, 10 Jul 2024 09:33:24 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; secure) header.d=ffwll.ch header.i=@ffwll.ch header.b="WdXPFVCq"; dkim-atps=neutral Received: from mail-lf1-f48.google.com (mail-lf1-f48.google.com [209.85.167.48]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7628210E1C5 for ; Wed, 10 Jul 2024 09:33:23 +0000 (UTC) Received: by mail-lf1-f48.google.com with SMTP id 2adb3069b0e04-52ea84b6131so633595e87.3 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=lists.freedesktop.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=WdXPFVCqk0MBGZfFuQgbbGPpvT9XLTScyN36HYaulfhA7QgD1vcCeTOk3FoJvxXg/w AMidYNVyXoMNx2TnO+9JUKUxwvjFkWBRw2FeiViyxG9KZpLV7+6v+Cj4ZDl8RIRjPhfG yPiRHRlMh9/RsKGlsU+PlKavGUVwkgGf6AW5g= 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=iekMDS6GUI1An1svi2dzoj711xDLWok1a9uSuJVLjDEnHoHbmSOsR5gdbCoWNMliLq AZgYXszPjSSOmcn7FkQ/Hz+a/w77q0RgFUccha7dk5Xgq/cN6Xcme3Za2xa5um40pfEY SnA9oSJ5PHinsWZXw0waCuauh1WImrIg17mWw9uZtJUseDbaAtYGG7P0r+1a19mP9N7H pZ+9oDknDAyJx304cXP+wBDLu1/BkqLSKMDIUdkYZv2fb9UygMwvEVCaj0X2r+wvtSju oQg5VIkOQeQTC5emVcBhs45LCg0sXbfWByIGgORaUlXLX4PXcNNgJK8Ok27xwiMhjquf X8dA== X-Gm-Message-State: AOJu0YxFgKImFZE/LbLXj/zVR4WL9xWYvavQIHxMG0OA4/1VppXHDr0m Y6LfgCoVcziyqZXgYOwByBHgPgqDOu8v/DSryaGXMxMFCMKjmVpYpDeASYm2R42Sj0OaoeKfFO4 be78= 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 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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) From patchwork Wed Jul 10 09:31:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 13729127 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2AA1EC3DA42 for ; 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Wed, 10 Jul 2024 02:33:22 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4266f6f5a27sm73448935e9.23.2024.07.10.02.33.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jul 2024 02:33:22 -0700 (PDT) From: Daniel Vetter To: DRI Development , LKML Cc: Intel Graphics Development , Daniel Vetter , syzbot+6cebc1af246fe020a2f0@syzkaller.appspotmail.com, Daniel Vetter , stable@vger.kernel.org, Kent Overstreet , Brian Foster , linux-bcachefs@vger.kernel.org, Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky Subject: [PATCH 2/2] bcachefs: only console_trylock in bch2_print_string_as_lines Date: Wed, 10 Jul 2024 11:31:17 +0200 Message-ID: <20240710093120.732208-2-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240710093120.732208-1-daniel.vetter@ffwll.ch> References: <20240710093120.732208-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" console_lock is the outermost subsystem lock for a lot of subsystems, which means get/put_user must nest within. Which means it cannot be acquired somewhere deeply nested in other locks, and most definitely not while holding fs locks potentially needed to resolve faults. console_trylock is the best we can do here. Including printk folks since even trylock feels realyl iffy here to me. Reported-by: syzbot+6cebc1af246fe020a2f0@syzkaller.appspotmail.com References: https://lore.kernel.org/dri-devel/00000000000026c1ff061cd0de12@google.com/ Signed-off-by: Daniel Vetter Fixes: a8f354284304 ("bcachefs: bch2_print_string_as_lines()") Cc: # v6.7+ Cc: Kent Overstreet Cc: Brian Foster Cc: linux-bcachefs@vger.kernel.org Cc: Petr Mladek Cc: Steven Rostedt Cc: John Ogness Cc: Sergey Senozhatsky Signed-off-by: Daniel Vetter --- fs/bcachefs/util.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c index de331dec2a99..02381c653603 100644 --- a/fs/bcachefs/util.c +++ b/fs/bcachefs/util.c @@ -255,13 +255,14 @@ void bch2_prt_u64_base2(struct printbuf *out, u64 v) void bch2_print_string_as_lines(const char *prefix, const char *lines) { const char *p; + int locked; if (!lines) { printk("%s (null)\n", prefix); return; } - console_lock(); + locked = console_trylock(); while (1) { p = strchrnul(lines, '\n'); printk("%s%.*s\n", prefix, (int) (p - lines), lines); @@ -269,7 +270,8 @@ void bch2_print_string_as_lines(const char *prefix, const char *lines) break; lines = p + 1; } - console_unlock(); + if (locked) + console_unlock(); } int bch2_save_backtrace(bch_stacktrace *stack, struct task_struct *task, unsigned skipnr,