From d715ff8acbd5876549ef2b21b755ed919f40dcc1 Mon Sep 17 00:00:00 2001 From: Guoqing Jiang Date: Fri, 23 Oct 2020 09:43:46 +0200 Subject: [PATCH] RDMA/rtrs-srv: Don't guard the whole __alloc_srv with srv_mutex The purpose of srv_mutex is to protect srv_list as in put_srv, so no need to hold it when allocate memory for srv since it could be time consuming. Otherwise if one machine has limited memory, rsrv_close_work could be blocked for a longer time due to the mutex is held by get_or_create_srv since it can't get memory in time. INFO: task kworker/1:1:27478 blocked for more than 120 seconds. Tainted: G O 4.14.171-1-storage #4.14.171-1.3~deb9 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:1 D 0 27478 2 0x80000000 Workqueue: rtrs_server_wq rtrs_srv_close_work [rtrs_server] Call Trace: ? __schedule+0x38c/0x7e0 schedule+0x32/0x80 schedule_preempt_disabled+0xa/0x10 __mutex_lock.isra.2+0x25e/0x4d0 ? put_srv+0x44/0x100 [rtrs_server] put_srv+0x44/0x100 [rtrs_server] rtrs_srv_close_work+0x16c/0x280 [rtrs_server] process_one_work+0x1c5/0x3c0 worker_thread+0x47/0x3e0 kthread+0xfc/0x130 ? trace_event_raw_event_workqueue_execute_start+0xa0/0xa0 ? kthread_create_on_node+0x70/0x70 ret_from_fork+0x1f/0x30 Let's move all the logics from __find_srv_and_get and __alloc_srv to get_or_create_srv, and remove the two functions. Then it should be safe for multiple processes to access the same srv since it is protected with srv_mutex. And since we don't want to allocate chunks with srv_mutex held, let's check the srv->refcount after get srv because the chunks could not be allocated yet. Fixes: 9cb837480424 ("RDMA/rtrs: server: main functionality") Link: https://lore.kernel.org/r/20201023074353.21946-6-jinpu.wang@cloud.ionos.com Signed-off-by: Guoqing Jiang Signed-off-by: Jack Wang Signed-off-by: Jason Gunthorpe --- drivers/infiniband/ulp/rtrs/rtrs-srv.c | 114 +++++++++++-------------- 1 file changed, 51 insertions(+), 63 deletions(-) diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c index d6f93601712e..1cb778aff3c5 100644 --- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c +++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c @@ -1328,51 +1328,6 @@ static void rtrs_srv_dev_release(struct device *dev) kfree(srv); } -static struct rtrs_srv *__alloc_srv(struct rtrs_srv_ctx *ctx, - const uuid_t *paths_uuid) -{ - struct rtrs_srv *srv; - int i; - - srv = kzalloc(sizeof(*srv), GFP_KERNEL); - if (!srv) - return NULL; - - refcount_set(&srv->refcount, 1); - INIT_LIST_HEAD(&srv->paths_list); - mutex_init(&srv->paths_mutex); - mutex_init(&srv->paths_ev_mutex); - uuid_copy(&srv->paths_uuid, paths_uuid); - srv->queue_depth = sess_queue_depth; - srv->ctx = ctx; - device_initialize(&srv->dev); - srv->dev.release = rtrs_srv_dev_release; - - srv->chunks = kcalloc(srv->queue_depth, sizeof(*srv->chunks), - GFP_KERNEL); - if (!srv->chunks) - goto err_free_srv; - - for (i = 0; i < srv->queue_depth; i++) { - srv->chunks[i] = mempool_alloc(chunk_pool, GFP_KERNEL); - if (!srv->chunks[i]) - goto err_free_chunks; - } - list_add(&srv->ctx_list, &ctx->srv_list); - - return srv; - -err_free_chunks: - while (i--) - mempool_free(srv->chunks[i], chunk_pool); - kfree(srv->chunks); - -err_free_srv: - kfree(srv); - - return NULL; -} - static void free_srv(struct rtrs_srv *srv) { int i; @@ -1387,32 +1342,61 @@ static void free_srv(struct rtrs_srv *srv) put_device(&srv->dev); } -static inline struct rtrs_srv *__find_srv_and_get(struct rtrs_srv_ctx *ctx, - const uuid_t *paths_uuid) -{ - struct rtrs_srv *srv; - - list_for_each_entry(srv, &ctx->srv_list, ctx_list) { - if (uuid_equal(&srv->paths_uuid, paths_uuid) && - refcount_inc_not_zero(&srv->refcount)) - return srv; - } - - return NULL; -} - static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx, const uuid_t *paths_uuid) { struct rtrs_srv *srv; + int i; mutex_lock(&ctx->srv_mutex); - srv = __find_srv_and_get(ctx, paths_uuid); - if (!srv) - srv = __alloc_srv(ctx, paths_uuid); + list_for_each_entry(srv, &ctx->srv_list, ctx_list) { + if (uuid_equal(&srv->paths_uuid, paths_uuid) && + refcount_inc_not_zero(&srv->refcount)) { + mutex_unlock(&ctx->srv_mutex); + return srv; + } + } + + /* need to allocate a new srv */ + srv = kzalloc(sizeof(*srv), GFP_KERNEL); + if (!srv) { + mutex_unlock(&ctx->srv_mutex); + return NULL; + } + + INIT_LIST_HEAD(&srv->paths_list); + mutex_init(&srv->paths_mutex); + mutex_init(&srv->paths_ev_mutex); + uuid_copy(&srv->paths_uuid, paths_uuid); + srv->queue_depth = sess_queue_depth; + srv->ctx = ctx; + device_initialize(&srv->dev); + srv->dev.release = rtrs_srv_dev_release; + list_add(&srv->ctx_list, &ctx->srv_list); mutex_unlock(&ctx->srv_mutex); + srv->chunks = kcalloc(srv->queue_depth, sizeof(*srv->chunks), + GFP_KERNEL); + if (!srv->chunks) + goto err_free_srv; + + for (i = 0; i < srv->queue_depth; i++) { + srv->chunks[i] = mempool_alloc(chunk_pool, GFP_KERNEL); + if (!srv->chunks[i]) + goto err_free_chunks; + } + refcount_set(&srv->refcount, 1); + return srv; + +err_free_chunks: + while (i--) + mempool_free(srv->chunks[i], chunk_pool); + kfree(srv->chunks); + +err_free_srv: + kfree(srv); + return NULL; } static void put_srv(struct rtrs_srv *srv) @@ -1813,7 +1797,11 @@ static int rtrs_rdma_connect(struct rdma_cm_id *cm_id, } recon_cnt = le16_to_cpu(msg->recon_cnt); srv = get_or_create_srv(ctx, &msg->paths_uuid); - if (!srv) { + /* + * "refcount == 0" happens if a previous thread calls get_or_create_srv + * allocate srv, but chunks of srv are not allocated yet. + */ + if (!srv || refcount_read(&srv->refcount) == 0) { err = -ENOMEM; goto reject_w_err; }