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    Subject[PATCH 5.13 107/266] drm/amdkfd: Fix circular lock in nocpsch path
    Date
    From: Amber Lin <Amber.Lin@amd.com>

    [ Upstream commit a7b2451d31cfa2e8aeccf3b35612ce33f02371fc ]

    Calling free_mqd inside of destroy_queue_nocpsch_locked can cause a
    circular lock. destroy_queue_nocpsch_locked is called under a DQM lock,
    which is taken in MMU notifiers, potentially in FS reclaim context.
    Taking another lock, which is BO reservation lock from free_mqd, while
    causing an FS reclaim inside the DQM lock creates a problematic circular
    lock dependency. Therefore move free_mqd out of
    destroy_queue_nocpsch_locked and call it after unlocking DQM.

    Signed-off-by: Amber Lin <Amber.Lin@amd.com>
    Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    .../drm/amd/amdkfd/kfd_device_queue_manager.c | 18 +++++++++++++-----
    1 file changed, 13 insertions(+), 5 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 ccc9d108caff..e9b3e2e32bf8 100644
    --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
    +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
    @@ -486,9 +486,6 @@ static int destroy_queue_nocpsch_locked(struct device_queue_manager *dqm,
    if (retval == -ETIME)
    qpd->reset_wavefronts = true;

    -
    - mqd_mgr->free_mqd(mqd_mgr, q->mqd, q->mqd_mem_obj);
    -
    list_del(&q->list);
    if (list_empty(&qpd->queues_list)) {
    if (qpd->reset_wavefronts) {
    @@ -523,6 +520,8 @@ static int destroy_queue_nocpsch(struct device_queue_manager *dqm,
    int retval;
    uint64_t sdma_val = 0;
    struct kfd_process_device *pdd = qpd_to_pdd(qpd);
    + struct mqd_manager *mqd_mgr =
    + dqm->mqd_mgrs[get_mqd_type_from_queue_type(q->properties.type)];

    /* Get the SDMA queue stats */
    if ((q->properties.type == KFD_QUEUE_TYPE_SDMA) ||
    @@ -540,6 +539,8 @@ static int destroy_queue_nocpsch(struct device_queue_manager *dqm,
    pdd->sdma_past_activity_counter += sdma_val;
    dqm_unlock(dqm);

    + mqd_mgr->free_mqd(mqd_mgr, q->mqd, q->mqd_mem_obj);
    +
    return retval;
    }

    @@ -1629,7 +1630,7 @@ out:
    static int process_termination_nocpsch(struct device_queue_manager *dqm,
    struct qcm_process_device *qpd)
    {
    - struct queue *q, *next;
    + struct queue *q;
    struct device_process_node *cur, *next_dpn;
    int retval = 0;
    bool found = false;
    @@ -1637,12 +1638,19 @@ static int process_termination_nocpsch(struct device_queue_manager *dqm,
    dqm_lock(dqm);

    /* Clear all user mode queues */
    - list_for_each_entry_safe(q, next, &qpd->queues_list, list) {
    + while (!list_empty(&qpd->queues_list)) {
    + struct mqd_manager *mqd_mgr;
    int ret;

    + q = list_first_entry(&qpd->queues_list, struct queue, list);
    + mqd_mgr = dqm->mqd_mgrs[get_mqd_type_from_queue_type(
    + q->properties.type)];
    ret = destroy_queue_nocpsch_locked(dqm, qpd, q);
    if (ret)
    retval = ret;
    + dqm_unlock(dqm);
    + mqd_mgr->free_mqd(mqd_mgr, q->mqd, q->mqd_mem_obj);
    + dqm_lock(dqm);
    }

    /* Unregister process */
    --
    2.30.2


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