From patchwork Thu Aug 3 22:01:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rob Clark X-Patchwork-Id: 13340885 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0DE70C04A94 for ; Thu, 3 Aug 2023 22:02:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231743AbjHCWC1 (ORCPT ); Thu, 3 Aug 2023 18:02:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231947AbjHCWC0 (ORCPT ); Thu, 3 Aug 2023 18:02:26 -0400 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0F6B3C23; Thu, 3 Aug 2023 15:02:24 -0700 (PDT) Received: by mail-pl1-x62f.google.com with SMTP id d9443c01a7336-1bbf0f36ce4so10321375ad.0; Thu, 03 Aug 2023 15:02:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1691100144; x=1691704944; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=DIKm3KXW0BL2JyogAnZ2vg+/kVkCrZycjm7nvt+Ji58=; b=ErSK6InaI2pfpjFZspAp/kNj9zIU5+BxZiqjMBfiIJhN75pDYYqTMlzG6LeNzoR/fo LmHAivo7tSOek8dLbFEFdzmj7gVNIZdFh5RoeHxdH11ujLS9ZctBk1hH04ZGh/NlaFy8 qz3SWdX4Q71xt13jtSLKWMEYPwPibuDFSfE8ePtQKLW7YKIa3AvmHgAitHCeqTWNuWTp qoa+q6SN5gc3gOeVK6XiUmjaVCaFXUBdT/uNzXyD9iVGCX+SEra+pPTYA83wxCmnTFOV WaRp0/ZtRkv6EoUMkCGBJNV6cd1s/Ozt/atKCrEMAiaoAnc8Q5vAmIRbOossilUSqRCC kuZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691100144; x=1691704944; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=DIKm3KXW0BL2JyogAnZ2vg+/kVkCrZycjm7nvt+Ji58=; b=Tja72HdRoKsBmkhD7m7QOPzyf1+fqFC9GKM2A/iSep3MCLuYl6SGQnoqrUrRhdRNhk 1jGDgloJ0huEL9khHTjK0BQlVr7Si3H9oFnqonLHjWbApnnclyU1VF7+iBbXtLzNegNY AxQFL3uwjZDCYvx/fEjmyI+FLH/tQ2ENLcN0pCclPZVbzbX6CkuUAoWJKva7FSpTNoSU Mh5gxlgx30Tmk4SEep0ttKH6Ehtvm16cjmRyJ/IH8MaG0ezrpLEpXWAQHo2N14lc/emx 4WlsmxtkFnV76eP/69ZXlcMSR7GqFjyq7J3kzqpT1v/H2/wkNJLzGdMbQFZ3Uw08Q0HK Jdew== X-Gm-Message-State: AOJu0YzMNSpzgvNsNYzUXmoO916V8iIc4QwlWoALApNyt7MYDv4WIXOM Dy0ZC4aVJjqqJyBsFwCLglo= X-Google-Smtp-Source: AGHT+IGOfO4T/mMTJ+qviNyTQJesL5WbocShHrK0MjyWuhluP9cjAzdpQj0LHnj+pFHXigjXR13k0A== X-Received: by 2002:a17:903:1205:b0:1bc:e6a:205f with SMTP id l5-20020a170903120500b001bc0e6a205fmr19215plh.20.1691100143953; Thu, 03 Aug 2023 15:02:23 -0700 (PDT) Received: from localhost ([2a00:79e1:abd:4a00:6c80:7c10:75a0:44f4]) by smtp.gmail.com with ESMTPSA id q8-20020a170902a3c800b001bba7002132sm338824plb.33.2023.08.03.15.02.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Aug 2023 15:02:23 -0700 (PDT) From: Rob Clark To: dri-devel@lists.freedesktop.org Cc: linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, Rob Clark , "Rafael J. Wysocki" , Pavel Machek , Len Brown , Greg Kroah-Hartman , linux-pm@vger.kernel.org (open list:HIBERNATION (aka Software Suspend, aka swsusp)), linux-kernel@vger.kernel.org (open list) Subject: [PATCH v3 3/9] PM / QoS: Fix constraints alloc vs reclaim locking Date: Thu, 3 Aug 2023 15:01:51 -0700 Message-ID: <20230803220202.78036-4-robdclark@gmail.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230803220202.78036-1-robdclark@gmail.com> References: <20230803220202.78036-1-robdclark@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Rob Clark In the process of adding lockdep annotation for drm GPU scheduler's job_run() to detect potential deadlock against shrinker/reclaim, I hit this lockdep splat: ====================================================== WARNING: possible circular locking dependency detected 6.2.0-rc8-debug+ #558 Tainted: G W ------------------------------------------------------ ring0/125 is trying to acquire lock: ffffffd6d6ce0f28 (dev_pm_qos_mtx){+.+.}-{3:3}, at: dev_pm_qos_update_request+0x38/0x68 but task is already holding lock: ffffff8087239208 (&gpu->active_lock){+.+.}-{3:3}, at: msm_gpu_submit+0xec/0x178 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&gpu->active_lock){+.+.}-{3:3}: __mutex_lock+0xcc/0x3c8 mutex_lock_nested+0x30/0x44 msm_gpu_submit+0xec/0x178 msm_job_run+0x78/0x150 drm_sched_main+0x290/0x370 kthread+0xf0/0x100 ret_from_fork+0x10/0x20 -> #3 (dma_fence_map){++++}-{0:0}: __dma_fence_might_wait+0x74/0xc0 dma_resv_lockdep+0x1f4/0x2f4 do_one_initcall+0x104/0x2bc kernel_init_freeable+0x344/0x34c kernel_init+0x30/0x134 ret_from_fork+0x10/0x20 -> #2 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}: fs_reclaim_acquire+0x80/0xa8 slab_pre_alloc_hook.constprop.0+0x40/0x25c __kmem_cache_alloc_node+0x60/0x1cc __kmalloc+0xd8/0x100 topology_parse_cpu_capacity+0x8c/0x178 get_cpu_for_node+0x88/0xc4 parse_cluster+0x1b0/0x28c parse_cluster+0x8c/0x28c init_cpu_topology+0x168/0x188 smp_prepare_cpus+0x24/0xf8 kernel_init_freeable+0x18c/0x34c kernel_init+0x30/0x134 ret_from_fork+0x10/0x20 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire+0x3c/0x48 fs_reclaim_acquire+0x54/0xa8 slab_pre_alloc_hook.constprop.0+0x40/0x25c __kmem_cache_alloc_node+0x60/0x1cc kmalloc_trace+0x50/0xa8 dev_pm_qos_constraints_allocate+0x38/0x100 __dev_pm_qos_add_request+0xb0/0x1e8 dev_pm_qos_add_request+0x58/0x80 dev_pm_qos_expose_latency_limit+0x60/0x13c register_cpu+0x12c/0x130 topology_init+0xac/0xbc do_one_initcall+0x104/0x2bc kernel_init_freeable+0x344/0x34c kernel_init+0x30/0x134 ret_from_fork+0x10/0x20 -> #0 (dev_pm_qos_mtx){+.+.}-{3:3}: __lock_acquire+0xe00/0x1060 lock_acquire+0x1e0/0x2f8 __mutex_lock+0xcc/0x3c8 mutex_lock_nested+0x30/0x44 dev_pm_qos_update_request+0x38/0x68 msm_devfreq_boost+0x40/0x70 msm_devfreq_active+0xc0/0xf0 msm_gpu_submit+0x10c/0x178 msm_job_run+0x78/0x150 drm_sched_main+0x290/0x370 kthread+0xf0/0x100 ret_from_fork+0x10/0x20 other info that might help us debug this: Chain exists of: dev_pm_qos_mtx --> dma_fence_map --> &gpu->active_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&gpu->active_lock); lock(dma_fence_map); lock(&gpu->active_lock); lock(dev_pm_qos_mtx); *** DEADLOCK *** 3 locks held by ring0/123: #0: ffffff8087251170 (&gpu->lock){+.+.}-{3:3}, at: msm_job_run+0x64/0x150 #1: ffffffd00b0e57e8 (dma_fence_map){++++}-{0:0}, at: msm_job_run+0x68/0x150 #2: ffffff8087251208 (&gpu->active_lock){+.+.}-{3:3}, at: msm_gpu_submit+0xec/0x178 stack backtrace: CPU: 6 PID: 123 Comm: ring0 Not tainted 6.2.0-rc8-debug+ #559 Hardware name: Google Lazor (rev1 - 2) with LTE (DT) Call trace: dump_backtrace.part.0+0xb4/0xf8 show_stack+0x20/0x38 dump_stack_lvl+0x9c/0xd0 dump_stack+0x18/0x34 print_circular_bug+0x1b4/0x1f0 check_noncircular+0x78/0xac __lock_acquire+0xe00/0x1060 lock_acquire+0x1e0/0x2f8 __mutex_lock+0xcc/0x3c8 mutex_lock_nested+0x30/0x44 dev_pm_qos_update_request+0x38/0x68 msm_devfreq_boost+0x40/0x70 msm_devfreq_active+0xc0/0xf0 msm_gpu_submit+0x10c/0x178 msm_job_run+0x78/0x150 drm_sched_main+0x290/0x370 kthread+0xf0/0x100 ret_from_fork+0x10/0x20 The issue is that dev_pm_qos_mtx is held in the runpm suspend/resume (or freq change) path, but it is also held across allocations that could recurse into shrinker. Solve this by changing dev_pm_qos_constraints_allocate() into a function that can be called unconditionally before the device qos object is needed and before aquiring dev_pm_qos_mtx. This way the allocations can be done without holding the mutex. In the case that we raced with another thread to allocate the qos object, detect this *after* acquiring the dev_pm_qos_mtx and simply free the redundant allocations. Signed-off-by: Rob Clark --- drivers/base/power/qos.c | 60 +++++++++++++++++++++++++++------------- 1 file changed, 41 insertions(+), 19 deletions(-) diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c index 8e93167f1783..f3e0c6b65635 100644 --- a/drivers/base/power/qos.c +++ b/drivers/base/power/qos.c @@ -185,18 +185,24 @@ static int apply_constraint(struct dev_pm_qos_request *req, } /* - * dev_pm_qos_constraints_allocate + * dev_pm_qos_constraints_ensure_allocated * @dev: device to allocate data for * - * Called at the first call to add_request, for constraint data allocation - * Must be called with the dev_pm_qos_mtx mutex held + * Called to ensure that devices qos is allocated, before acquiring + * dev_pm_qos_mtx. */ -static int dev_pm_qos_constraints_allocate(struct device *dev) +static int dev_pm_qos_constraints_ensure_allocated(struct device *dev) { struct dev_pm_qos *qos; struct pm_qos_constraints *c; struct blocking_notifier_head *n; + if (!dev) + return -ENODEV; + + if (!IS_ERR_OR_NULL(dev->power.qos)) + return 0; + qos = kzalloc(sizeof(*qos), GFP_KERNEL); if (!qos) return -ENOMEM; @@ -227,10 +233,26 @@ static int dev_pm_qos_constraints_allocate(struct device *dev) INIT_LIST_HEAD(&qos->flags.list); + mutex_lock(&dev_pm_qos_mtx); + + if (!IS_ERR_OR_NULL(dev->power.qos)) { + /* + * We have raced with another task to create the qos. + * No biggie, just free the resources we've allocated + * outside of dev_pm_qos_mtx and move on with life. + */ + kfree(n); + kfree(qos); + goto unlock; + } + spin_lock_irq(&dev->power.lock); dev->power.qos = qos; spin_unlock_irq(&dev->power.lock); +unlock: + mutex_unlock(&dev_pm_qos_mtx); + return 0; } @@ -331,17 +353,15 @@ static int __dev_pm_qos_add_request(struct device *dev, { int ret = 0; - if (!dev || !req || dev_pm_qos_invalid_req_type(dev, type)) + if (!req || dev_pm_qos_invalid_req_type(dev, type)) return -EINVAL; if (WARN(dev_pm_qos_request_active(req), "%s() called for already added request\n", __func__)) return -EINVAL; - if (IS_ERR(dev->power.qos)) + if (IS_ERR_OR_NULL(dev->power.qos)) ret = -ENODEV; - else if (!dev->power.qos) - ret = dev_pm_qos_constraints_allocate(dev); trace_dev_pm_qos_add_request(dev_name(dev), type, value); if (ret) @@ -390,6 +410,10 @@ int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, { int ret; + ret = dev_pm_qos_constraints_ensure_allocated(dev); + if (ret) + return ret; + mutex_lock(&dev_pm_qos_mtx); ret = __dev_pm_qos_add_request(dev, req, type, value); mutex_unlock(&dev_pm_qos_mtx); @@ -537,15 +561,11 @@ int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier, { int ret = 0; - mutex_lock(&dev_pm_qos_mtx); - - if (IS_ERR(dev->power.qos)) - ret = -ENODEV; - else if (!dev->power.qos) - ret = dev_pm_qos_constraints_allocate(dev); - + ret = dev_pm_qos_constraints_ensure_allocated(dev); if (ret) - goto unlock; + return ret; + + mutex_lock(&dev_pm_qos_mtx); switch (type) { case DEV_PM_QOS_RESUME_LATENCY: @@ -565,7 +585,6 @@ int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier, ret = -EINVAL; } -unlock: mutex_unlock(&dev_pm_qos_mtx); return ret; } @@ -905,10 +924,13 @@ int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val) { int ret; + ret = dev_pm_qos_constraints_ensure_allocated(dev); + if (ret) + return ret; + mutex_lock(&dev_pm_qos_mtx); - if (IS_ERR_OR_NULL(dev->power.qos) - || !dev->power.qos->latency_tolerance_req) { + if (!dev->power.qos->latency_tolerance_req) { struct dev_pm_qos_request *req; if (val < 0) {