From patchwork Fri Apr 22 19:44:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhu Yanjun X-Patchwork-Id: 12822712 X-Patchwork-Delegate: jgg@ziepe.ca 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 B8DA1C433F5 for ; Fri, 22 Apr 2022 03:17:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242102AbiDVDUk (ORCPT ); Thu, 21 Apr 2022 23:20:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1443716AbiDVDUj (ORCPT ); Thu, 21 Apr 2022 23:20:39 -0400 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DCFA4D623 for ; Thu, 21 Apr 2022 20:17:47 -0700 (PDT) X-IronPort-AV: E=McAfee;i="6400,9594,10324"; a="350994641" X-IronPort-AV: E=Sophos;i="5.90,280,1643702400"; d="scan'208";a="350994641" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Apr 2022 20:17:46 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,280,1643702400"; d="scan'208";a="615218036" Received: from unknown (HELO intel-71.bj.intel.com) ([10.238.154.71]) by fmsmga008.fm.intel.com with ESMTP; 21 Apr 2022 20:17:45 -0700 From: yanjun.zhu@linux.dev To: jgg@ziepe.ca, leon@kernel.org, linux-rdma@vger.kernel.org, yanjun.zhu@linux.dev Cc: Yi Zhang Subject: [PATCHv6 1/4] RDMA/rxe: Fix dead lock caused by __rxe_add_to_pool interrupted by rxe_pool_get_index Date: Fri, 22 Apr 2022 15:44:13 -0400 Message-Id: <20220422194416.983549-1-yanjun.zhu@linux.dev> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org From: Zhu Yanjun This is a dead lock problem. The ah_pool xa_lock first is acquired in this: {SOFTIRQ-ON-W} state was registered at: lock_acquire+0x1d2/0x5a0 _raw_spin_lock+0x33/0x80 __rxe_add_to_pool+0x183/0x230 [rdma_rxe] Then ah_pool xa_lock is acquired in this: {IN-SOFTIRQ-W}: Call Trace: dump_stack_lvl+0x44/0x57 mark_lock.part.52.cold.79+0x3c/0x46 __lock_acquire+0x1565/0x34a0 lock_acquire+0x1d2/0x5a0 _raw_spin_lock_irqsave+0x42/0x90 rxe_pool_get_index+0x72/0x1d0 [rdma_rxe] rxe_get_av+0x168/0x2a0 [rdma_rxe] From the above, in the function __rxe_add_to_pool, xa_lock is acquired. Then the function __rxe_add_to_pool is interrupted by softirq. The function rxe_pool_get_index will also acquire xa_lock. Finally, the dead lock appears. CPU0 ---- lock(&xa->xa_lock#15); <----- __rxe_add_to_pool lock(&xa->xa_lock#15); <---- rxe_pool_get_index *** DEADLOCK *** Fixes: 3225717f6dfa ("RDMA/rxe: Replace red-black trees by carrays") Reported-and-tested-by: Yi Zhang Signed-off-by: Zhu Yanjun Signed-off-by: Zhu Yanjun --- V5->V6: One dead lock fix in one commit V4->V5: Commit logs are changed. V3->V4: xa_lock_irq locks are used. V2->V3: __rxe_add_to_pool is between spin_lock and spin_unlock, so GFP_ATOMIC is used in __rxe_add_to_pool. V1->V2: Replace GFP_KERNEL with GFP_ATOMIC --- drivers/infiniband/sw/rxe/rxe_pool.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c index 87066d04ed18..67f1d4733682 100644 --- a/drivers/infiniband/sw/rxe/rxe_pool.c +++ b/drivers/infiniband/sw/rxe/rxe_pool.c @@ -106,7 +106,7 @@ void rxe_pool_init(struct rxe_dev *rxe, struct rxe_pool *pool, atomic_set(&pool->num_elem, 0); - xa_init_flags(&pool->xa, XA_FLAGS_ALLOC); + xa_init_flags(&pool->xa, XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ); pool->limit.min = info->min_index; pool->limit.max = info->max_index; } @@ -155,6 +155,7 @@ void *rxe_alloc(struct rxe_pool *pool) int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem) { int err; + unsigned long flags; if (WARN_ON(pool->flags & RXE_POOL_ALLOC)) return -EINVAL; @@ -166,8 +167,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem) elem->obj = (u8 *)elem - pool->elem_offset; kref_init(&elem->ref_cnt); - err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit, - &pool->next, GFP_KERNEL); + xa_lock_irqsave(&pool->xa, flags); + err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit, + &pool->next, GFP_ATOMIC); + xa_unlock_irqrestore(&pool->xa, flags); if (err) goto err_cnt; @@ -201,7 +204,7 @@ static void rxe_elem_release(struct kref *kref) struct rxe_pool_elem *elem = container_of(kref, typeof(*elem), ref_cnt); struct rxe_pool *pool = elem->pool; - xa_erase(&pool->xa, elem->index); + xa_erase_irq(&pool->xa, elem->index); if (pool->cleanup) pool->cleanup(elem);