From d69fd951e60ae48c8dd100aa8ceb799ab965f9b3 Mon Sep 17 00:00:00 2001 From: Mukul Joshi Date: Wed, 24 Jun 2020 13:47:12 -0400 Subject: [PATCH] drm/amdkfd: Fix circular locking dependency warning [ 150.887733] ====================================================== [ 150.893903] WARNING: possible circular locking dependency detected [ 150.905917] ------------------------------------------------------ [ 150.912129] kfdtest/4081 is trying to acquire lock: [ 150.917002] ffff8f7f3762e118 (&mm->mmap_sem#2){++++}, at: __might_fault+0x3e/0x90 [ 150.924490] but task is already holding lock: [ 150.930320] ffff8f7f49d229e8 (&dqm->lock_hidden){+.+.}, at: destroy_queue_cpsch+0x29/0x210 [amdgpu] [ 150.939432] which lock already depends on the new lock. [ 150.947603] the existing dependency chain (in reverse order) is: [ 150.955074] -> #3 (&dqm->lock_hidden){+.+.}: [ 150.960822] __mutex_lock+0xa1/0x9f0 [ 150.964996] evict_process_queues_cpsch+0x22/0x120 [amdgpu] [ 150.971155] kfd_process_evict_queues+0x3b/0xc0 [amdgpu] [ 150.977054] kgd2kfd_quiesce_mm+0x25/0x60 [amdgpu] [ 150.982442] amdgpu_amdkfd_evict_userptr+0x35/0x70 [amdgpu] [ 150.988615] amdgpu_mn_invalidate_hsa+0x41/0x60 [amdgpu] [ 150.994448] __mmu_notifier_invalidate_range_start+0xa4/0x240 [ 151.000714] copy_page_range+0xd70/0xd80 [ 151.005159] dup_mm+0x3ca/0x550 [ 151.008816] copy_process+0x1bdc/0x1c70 [ 151.013183] _do_fork+0x76/0x6c0 [ 151.016929] __x64_sys_clone+0x8c/0xb0 [ 151.021201] do_syscall_64+0x4a/0x1d0 [ 151.025404] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 151.030977] -> #2 (&adev->notifier_lock){+.+.}: [ 151.036993] __mutex_lock+0xa1/0x9f0 [ 151.041168] amdgpu_mn_invalidate_hsa+0x30/0x60 [amdgpu] [ 151.047019] __mmu_notifier_invalidate_range_start+0xa4/0x240 [ 151.053277] copy_page_range+0xd70/0xd80 [ 151.057722] dup_mm+0x3ca/0x550 [ 151.061388] copy_process+0x1bdc/0x1c70 [ 151.065748] _do_fork+0x76/0x6c0 [ 151.069499] __x64_sys_clone+0x8c/0xb0 [ 151.073765] do_syscall_64+0x4a/0x1d0 [ 151.077952] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 151.083523] -> #1 (mmu_notifier_invalidate_range_start){+.+.}: [ 151.090833] change_protection+0x802/0xab0 [ 151.095448] mprotect_fixup+0x187/0x2d0 [ 151.099801] setup_arg_pages+0x124/0x250 [ 151.104251] load_elf_binary+0x3a4/0x1464 [ 151.108781] search_binary_handler+0x6c/0x210 [ 151.113656] __do_execve_file.isra.40+0x7f7/0xa50 [ 151.118875] do_execve+0x21/0x30 [ 151.122632] call_usermodehelper_exec_async+0x17e/0x190 [ 151.128393] ret_from_fork+0x24/0x30 [ 151.132489] -> #0 (&mm->mmap_sem#2){++++}: [ 151.138064] __lock_acquire+0x11a1/0x1490 [ 151.142597] lock_acquire+0x90/0x180 [ 151.146694] __might_fault+0x68/0x90 [ 151.150879] read_sdma_queue_counter+0x5f/0xb0 [amdgpu] [ 151.156693] update_sdma_queue_past_activity_stats+0x3b/0x90 [amdgpu] [ 151.163725] destroy_queue_cpsch+0x1ae/0x210 [amdgpu] [ 151.169373] pqm_destroy_queue+0xf0/0x250 [amdgpu] [ 151.174762] kfd_ioctl_destroy_queue+0x32/0x70 [amdgpu] [ 151.180577] kfd_ioctl+0x223/0x400 [amdgpu] [ 151.185284] ksys_ioctl+0x8f/0xb0 [ 151.189118] __x64_sys_ioctl+0x16/0x20 [ 151.193389] do_syscall_64+0x4a/0x1d0 [ 151.197569] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 151.203141] other info that might help us debug this: [ 151.211140] Chain exists of: &mm->mmap_sem#2 --> &adev->notifier_lock --> &dqm->lock_hidden [ 151.222535] Possible unsafe locking scenario: [ 151.228447] CPU0 CPU1 [ 151.232971] ---- ---- [ 151.237502] lock(&dqm->lock_hidden); [ 151.241254] lock(&adev->notifier_lock); [ 151.247774] lock(&dqm->lock_hidden); [ 151.254038] lock(&mm->mmap_sem#2); This commit fixes the warning by ensuring get_user() is not called while reading SDMA stats with dqm_lock held as get_user() could cause a page fault which leads to the circular locking scenario. Signed-off-by: Mukul Joshi Reviewed-by: Felix Kuehling Signed-off-by: Alex Deucher --- .../gpu/drm/amd/amdkfd/kfd_device_queue_manager.c | 73 +++++------ .../gpu/drm/amd/amdkfd/kfd_device_queue_manager.h | 3 +- drivers/gpu/drm/amd/amdkfd/kfd_process.c | 143 ++++++++++++++++++--- 3 files changed, 158 insertions(+), 61 deletions(-) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c index 21eb099..dd55002 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c @@ -153,24 +153,23 @@ static void decrement_queue_count(struct device_queue_manager *dqm, dqm->active_cp_queue_count--; } -int read_sdma_queue_counter(struct queue *q, uint64_t *val) +int read_sdma_queue_counter(uint64_t q_rptr, uint64_t *val) { int ret; uint64_t tmp = 0; - if (!q || !val) + if (!val) return -EINVAL; /* * SDMA activity counter is stored at queue's RPTR + 0x8 location. */ - if (!access_ok((const void __user *)((uint64_t)q->properties.read_ptr + + if (!access_ok((const void __user *)(q_rptr + sizeof(uint64_t)), sizeof(uint64_t))) { pr_err("Can't access sdma queue activity counter\n"); return -EFAULT; } - ret = get_user(tmp, (uint64_t *)((uint64_t)(q->properties.read_ptr) + - sizeof(uint64_t))); + ret = get_user(tmp, (uint64_t *)(q_rptr + sizeof(uint64_t))); if (!ret) { *val = tmp; } @@ -178,27 +177,6 @@ int read_sdma_queue_counter(struct queue *q, uint64_t *val) return ret; } -static int update_sdma_queue_past_activity_stats(struct kfd_process_device *pdd, - struct queue *q) -{ - int ret; - uint64_t val = 0; - - if (!pdd) - return -ENODEV; - - ret = read_sdma_queue_counter(q, &val); - if (ret) { - pr_err("Failed to read SDMA queue counter for queue: %d\n", - q->properties.queue_id); - return ret; - } - - pdd->sdma_past_activity_counter += val; - - return ret; -} - static int allocate_doorbell(struct qcm_process_device *qpd, struct queue *q) { struct kfd_dev *dev = qpd->dqm->dev; @@ -533,11 +511,6 @@ static int destroy_queue_nocpsch_locked(struct device_queue_manager *dqm, if (retval == -ETIME) qpd->reset_wavefronts = true; - /* Get the SDMA queue stats */ - if ((q->properties.type == KFD_QUEUE_TYPE_SDMA) || - (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) { - update_sdma_queue_past_activity_stats(qpd_to_pdd(qpd), q); - } mqd_mgr->free_mqd(mqd_mgr, q->mqd, q->mqd_mem_obj); @@ -573,9 +546,23 @@ static int destroy_queue_nocpsch(struct device_queue_manager *dqm, struct queue *q) { int retval; + uint64_t sdma_val = 0; + struct kfd_process_device *pdd = qpd_to_pdd(qpd); + + /* Get the SDMA queue stats */ + if ((q->properties.type == KFD_QUEUE_TYPE_SDMA) || + (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) { + retval = read_sdma_queue_counter((uint64_t)q->properties.read_ptr, + &sdma_val); + if (retval) + pr_err("Failed to read SDMA queue counter for queue: %d\n", + q->properties.queue_id); + } dqm_lock(dqm); retval = destroy_queue_nocpsch_locked(dqm, qpd, q); + if (!retval) + pdd->sdma_past_activity_counter += sdma_val; dqm_unlock(dqm); return retval; @@ -1480,6 +1467,18 @@ static int destroy_queue_cpsch(struct device_queue_manager *dqm, { int retval; struct mqd_manager *mqd_mgr; + uint64_t sdma_val = 0; + struct kfd_process_device *pdd = qpd_to_pdd(qpd); + + /* Get the SDMA queue stats */ + if ((q->properties.type == KFD_QUEUE_TYPE_SDMA) || + (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) { + retval = read_sdma_queue_counter((uint64_t)q->properties.read_ptr, + &sdma_val); + if (retval) + pr_err("Failed to read SDMA queue counter for queue: %d\n", + q->properties.queue_id); + } retval = 0; @@ -1501,10 +1500,11 @@ static int destroy_queue_cpsch(struct device_queue_manager *dqm, deallocate_doorbell(qpd, q); - if (q->properties.type == KFD_QUEUE_TYPE_SDMA) - deallocate_sdma_queue(dqm, q); - else if (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI) + if ((q->properties.type == KFD_QUEUE_TYPE_SDMA) || + (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) { deallocate_sdma_queue(dqm, q); + pdd->sdma_past_activity_counter += sdma_val; + } list_del(&q->list); qpd->queue_count--; @@ -1520,11 +1520,6 @@ static int destroy_queue_cpsch(struct device_queue_manager *dqm, } } - /* Get the SDMA queue stats */ - if ((q->properties.type == KFD_QUEUE_TYPE_SDMA) || - (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) { - update_sdma_queue_past_activity_stats(qpd_to_pdd(qpd), q); - } /* * Unconditionally decrement this counter, regardless of the queue's * type diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h index 894bcf8..49d8e32 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h @@ -251,6 +251,5 @@ static inline void dqm_unlock(struct device_queue_manager *dqm) mutex_unlock(&dqm->lock_hidden); } -int read_sdma_queue_counter(struct queue *q, uint64_t *val); - +int read_sdma_queue_counter(uint64_t q_rptr, uint64_t *val); #endif /* KFD_DEVICE_QUEUE_MANAGER_H_ */ diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c index d0409df..013c2b0 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c @@ -86,6 +86,13 @@ struct kfd_sdma_activity_handler_workarea { uint64_t sdma_activity_counter; }; +struct temp_sdma_queue_list { + uint64_t rptr; + uint64_t sdma_val; + unsigned int queue_id; + struct list_head list; +}; + static void kfd_sdma_activity_worker(struct work_struct *work) { struct kfd_sdma_activity_handler_workarea *workarea; @@ -96,6 +103,8 @@ static void kfd_sdma_activity_worker(struct work_struct *work) struct qcm_process_device *qpd; struct device_queue_manager *dqm; int ret = 0; + struct temp_sdma_queue_list sdma_q_list; + struct temp_sdma_queue_list *sdma_q, *next; workarea = container_of(work, struct kfd_sdma_activity_handler_workarea, sdma_activity_work); @@ -109,41 +118,135 @@ static void kfd_sdma_activity_worker(struct work_struct *work) qpd = &pdd->qpd; if (!dqm || !qpd) return; + /* + * Total SDMA activity is current SDMA activity + past SDMA activity + * Past SDMA count is stored in pdd. + * To get the current activity counters for all active SDMA queues, + * we loop over all SDMA queues and get their counts from user-space. + * + * We cannot call get_user() with dqm_lock held as it can cause + * a circular lock dependency situation. To read the SDMA stats, + * we need to do the following: + * + * 1. Create a temporary list of SDMA queue nodes from the qpd->queues_list, + * with dqm_lock/dqm_unlock(). + * 2. Call get_user() for each node in temporary list without dqm_lock. + * Save the SDMA count for each node and also add the count to the total + * SDMA count counter. + * Its possible, during this step, a few SDMA queue nodes got deleted + * from the qpd->queues_list. + * 3. Do a second pass over qpd->queues_list to check if any nodes got deleted. + * If any node got deleted, its SDMA count would be captured in the sdma + * past activity counter. So subtract the SDMA counter stored in step 2 + * for this node from the total SDMA count. + */ + INIT_LIST_HEAD(&sdma_q_list.list); - mm = get_task_mm(pdd->process->lead_thread); - if (!mm) { - return; + /* + * Create the temp list of all SDMA queues + */ + dqm_lock(dqm); + + list_for_each_entry(q, &qpd->queues_list, list) { + if ((q->properties.type != KFD_QUEUE_TYPE_SDMA) && + (q->properties.type != KFD_QUEUE_TYPE_SDMA_XGMI)) + continue; + + sdma_q = kzalloc(sizeof(struct temp_sdma_queue_list), GFP_KERNEL); + if (!sdma_q) { + dqm_unlock(dqm); + goto cleanup; + } + + INIT_LIST_HEAD(&sdma_q->list); + sdma_q->rptr = (uint64_t)q->properties.read_ptr; + sdma_q->queue_id = q->properties.queue_id; + list_add_tail(&sdma_q->list, &sdma_q_list.list); } - use_mm(mm); + /* + * If the temp list is empty, then no SDMA queues nodes were found in + * qpd->queues_list. Return the past activity count as the total sdma + * count + */ + if (list_empty(&sdma_q_list.list)) { + workarea->sdma_activity_counter = pdd->sdma_past_activity_counter; + dqm_unlock(dqm); + return; + } - dqm_lock(dqm); + dqm_unlock(dqm); /* - * Total SDMA activity is current SDMA activity + past SDMA activity + * Get the usage count for each SDMA queue in temp_list. */ - workarea->sdma_activity_counter = pdd->sdma_past_activity_counter; + mm = get_task_mm(pdd->process->lead_thread); + if (!mm) + goto cleanup; + + use_mm(mm); + + list_for_each_entry(sdma_q, &sdma_q_list.list, list) { + val = 0; + ret = read_sdma_queue_counter(sdma_q->rptr, &val); + if (ret) { + pr_debug("Failed to read SDMA queue active counter for queue id: %d", + sdma_q->queue_id); + } else { + sdma_q->sdma_val = val; + workarea->sdma_activity_counter += val; + } + } + + unuse_mm(mm); + mmput(mm); /* - * Get the current activity counters for all active SDMA queues + * Do a second iteration over qpd_queues_list to check if any SDMA + * nodes got deleted while fetching SDMA counter. */ + dqm_lock(dqm); + + workarea->sdma_activity_counter += pdd->sdma_past_activity_counter; + list_for_each_entry(q, &qpd->queues_list, list) { - if ((q->properties.type == KFD_QUEUE_TYPE_SDMA) || - (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) { - val = 0; - ret = read_sdma_queue_counter(q, &val); - if (ret) - pr_debug("Failed to read SDMA queue active " - "counter for queue id: %d", - q->properties.queue_id); - else - workarea->sdma_activity_counter += val; + if (list_empty(&sdma_q_list.list)) + break; + + if ((q->properties.type != KFD_QUEUE_TYPE_SDMA) && + (q->properties.type != KFD_QUEUE_TYPE_SDMA_XGMI)) + continue; + + list_for_each_entry_safe(sdma_q, next, &sdma_q_list.list, list) { + if (((uint64_t)q->properties.read_ptr == sdma_q->rptr) && + (sdma_q->queue_id == q->properties.queue_id)) { + list_del(&sdma_q->list); + kfree(sdma_q); + break; + } } } dqm_unlock(dqm); - unuse_mm(mm); - mmput(mm); + + /* + * If temp list is not empty, it implies some queues got deleted + * from qpd->queues_list during SDMA usage read. Subtract the SDMA + * count for each node from the total SDMA count. + */ + list_for_each_entry_safe(sdma_q, next, &sdma_q_list.list, list) { + workarea->sdma_activity_counter -= sdma_q->sdma_val; + list_del(&sdma_q->list); + kfree(sdma_q); + } + + return; + +cleanup: + list_for_each_entry_safe(sdma_q, next, &sdma_q_list.list, list) { + list_del(&sdma_q->list); + kfree(sdma_q); + } } static ssize_t kfd_procfs_show(struct kobject *kobj, struct attribute *attr, -- 2.7.4