From mboxrd@z Thu Jan 1 00:00:00 1970 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 9035FC433EF for ; Tue, 12 Apr 2022 13:53:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356367AbiDLNzh (ORCPT ); Tue, 12 Apr 2022 09:55:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356352AbiDLNze (ORCPT ); Tue, 12 Apr 2022 09:55:34 -0400 Received: from mail-qk1-x732.google.com (mail-qk1-x732.google.com [IPv6:2607:f8b0:4864:20::732]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A7C457B35 for ; Tue, 12 Apr 2022 06:53:15 -0700 (PDT) Received: by mail-qk1-x732.google.com with SMTP id j6so13731046qkp.9 for ; Tue, 12 Apr 2022 06:53:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=PBuMAH3rTUpfxI+mZt/ZTT/N3YWTiBg1EJgACsNMZPE=; b=IRlwmzizWP/FSNval8NC5Ggc4mxJ7LERA3iAuMqYVZaaKsd/1Vxj7vuT9rH3rD9EFy lbvwSSnM+p+OslNOPAGJxj5qqav+4SHIy4jJa+JmnADPAdO+k1Vw108LQksmynv8cNmS Rowrldh3iFELPVVMCkue9aSX5LRkmHJTmWfz2W/vpyjSJghO1VN0x1plzayEp5QW9q7D YI4pup9FqTsCnFwAPPxZVzxnq6VhgCDkdebu8EVVn4r/3Eigdt4eRWHtAy+XLWazh9OL V7DZxDA+wczrQK3OzhUOV5D5+qqTYQ8BCgJsFFfr60h9qDXyrlSYIp1UUQX6TAI2DYBa /oKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=PBuMAH3rTUpfxI+mZt/ZTT/N3YWTiBg1EJgACsNMZPE=; b=eoWDLFXtk0n1ich910pnfV8s/0KR+wRS4M6FBIycZBwJsB5Az+7CSvzcmHkzIY6PPY Mn09IMo+zPdwjzjlFxM1XsozgF+K6op9RqCHwbd9T4f5wflNTCpDCEvaDovlS1bxfg2+ 7LybfOfhCe9cQCjhiiP8pzcIXzz+IBpp98QEQKMR2j3UshXvSVSViMrez6usXao2MZut ySRtSiIMgVnMfXqeJ+MxAvMO1sHYU3ycX8814RjJaj7OaR4Nrj9FO6HIjhLSiD7gtdPm +2R0VCQr4oXx/i7Ao2LabStiAAUkqZsxCfkXhow8sZDwQTAXo5c1/VnpfwZ5l8pS7OGK S8kw== X-Gm-Message-State: AOAM531zgIPbMVlq0wZ+ivYJ++5cY46vqi1jG7BFW5SrQMmuoe3hk9FK Xg83kHYGbzOHnBkNhLw431rtItaQIO4jNQ== X-Google-Smtp-Source: ABdhPJzN4R3N/Vhy3eyCfGaMlAHK5PFg+8lpkEz9oHhWna3/aLeAbnO2OaqcjQcN5BlYsRLQ6sNXbg== X-Received: by 2002:a05:620a:148c:b0:69b:ef4d:ada1 with SMTP id w12-20020a05620a148c00b0069bef4dada1mr3120812qkj.608.1649771594247; Tue, 12 Apr 2022 06:53:14 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-162-113-129.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.129]) by smtp.gmail.com with ESMTPSA id 8-20020ac85948000000b002e1cd3fa142sm28980283qtz.92.2022.04.12.06.53.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Apr 2022 06:53:13 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1neGxF-000rE0-1J; Tue, 12 Apr 2022 10:53:13 -0300 Date: Tue, 12 Apr 2022 10:53:13 -0300 From: Jason Gunthorpe To: Yanjun Zhu Cc: zyjzyj2000@gmail.com, leon@kernel.org, linux-rdma@vger.kernel.org, Yi Zhang Subject: Re: [PATCHv2 1/1] RDMA/rxe: Fix a dead lock problem Message-ID: <20220412135313.GD64706@ziepe.ca> References: <20220411200018.1363127-1-yanjun.zhu@linux.dev> <20220411115019.GB64706@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Apr 12, 2022 at 09:43:28PM +0800, Yanjun Zhu wrote: > 在 2022/4/11 19:50, Jason Gunthorpe 写道: > > On Mon, Apr 11, 2022 at 04:00:18PM -0400, yanjun.zhu@linux.dev wrote: > > > @@ -138,8 +139,10 @@ void *rxe_alloc(struct rxe_pool *pool) > > > elem->obj = obj; > > > 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); > > > > No to using atomics, this needs to be either the _irq or _bh varient > > If I understand you correctly, you mean that we should use > xa_lock_irq/xa_unlock_irq or xa_lock_bh/xa_unlock_bh instead of > xa_unlock_irqrestore? This is correct > If so, xa_lock_irq/xa_unlock_irq or xa_lock_bh/xa_unlock_bh is used here, > the warning as below will appear. This means that __rxe_add_to_pool disables > softirq, but fpu_clone enables softirq. I don't know what this is, you need to show the whole debug. fpu_clone does not call rxe_add_to_pool > As such, it is better to use xa_unlock_irqrestore + > __xa_alloc(...,GFP_ATOMIC/GFP_NOWAIT). No Jason