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 129D9C433F5 for ; Mon, 11 Apr 2022 03:13:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239857AbiDKDPb (ORCPT ); Sun, 10 Apr 2022 23:15:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241552AbiDKDPa (ORCPT ); Sun, 10 Apr 2022 23:15:30 -0400 Received: from mail-ot1-x32f.google.com (mail-ot1-x32f.google.com [IPv6:2607:f8b0:4864:20::32f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5EE22F3AE; Sun, 10 Apr 2022 20:13:17 -0700 (PDT) Received: by mail-ot1-x32f.google.com with SMTP id o20-20020a9d7194000000b005cb20cf4f1bso10436636otj.7; Sun, 10 Apr 2022 20:13:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :references:from:in-reply-to:content-transfer-encoding; bh=VNJB7GSgI++flqJ/Poc6dwmZSl59SRvhL+rxI8N6WNs=; b=JylgToIBko0q4h5eaejYQ9IvPRyFlxcND7gd6TqAToN/n7XtjxbnTH9B3ason7DDtM bjWiZPenoMvqB5KIwGTSUhC1KPEGsPeTPq7AWVsWY5xN8fqOFH56Hwtk5wIJr1VamvaD IXNW62mRcRqek/eqdRz/sa0XlehJJhLqJ8bzTELvZw3Wc7S1eleCExtizi7nsqhNi0Vn uAfswydtg5t8uCZ18daD6w0Kjp0eCnhWBa+PsDAh5Y7pgl30UmFqyEBZDs/a6MLKrYJI tM8dIdT+rXNkrbMTKrpdszuDmcRK/2J3ik71AkgqR6g9XdmTqcJchenU51EL9OvW8sc9 3OAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:references:from:in-reply-to :content-transfer-encoding; bh=VNJB7GSgI++flqJ/Poc6dwmZSl59SRvhL+rxI8N6WNs=; b=h0FgQ7mtLHCROPddQ81eWuf6qGh1yKKTum2xJel0uNLTEDzT0et0Sp+dO4s2U6sjnF NR8HI5vS6mxqWDd/PrCs7rOxXoGKzwQXKN8p+VKSLSCc4GAXGM9LqA9RLKMQqVdi7MIk 12lps24rFgQBHblgzAEGt9XOWncMaH+Kp/YJq7DaelroTt0n6e7mO+n1k3t1kWIpIhJm Gr89AgbxApfG3YmsqpxfCRMU3PeXfW5guq92cLoc1FNK+V+1zaVQ32Lkb9n/IQU/5Fj9 O6/eWPPKl5TIUUlqSAzLvxQRuZkgmXitn9h9uLQsf7ExPjt0ikItM+XOqRWeVw/VH/Xq iMRw== X-Gm-Message-State: AOAM533BJp2FOwR8nJc4us6t7coimEhLlWDjkFan62Hvw0FdGw+H9/EY vYrsy5EoduU4n6lxT8WoE6o= X-Google-Smtp-Source: ABdhPJzDV/q5cw9wMWOVrDbIWtUEWwM4BD2c5QmvMXBt89Lbgjps1ONcNJkUz4A4DbVsNR6jgaclOg== X-Received: by 2002:a9d:77d7:0:b0:5b2:29b0:70cb with SMTP id w23-20020a9d77d7000000b005b229b070cbmr10269505otl.276.1649646797282; Sun, 10 Apr 2022 20:13:17 -0700 (PDT) Received: from ?IPV6:2603:8081:140c:1a00:8884:2210:b4d7:3f81? (2603-8081-140c-1a00-8884-2210-b4d7-3f81.res6.spectrum.com. [2603:8081:140c:1a00:8884:2210:b4d7:3f81]) by smtp.gmail.com with ESMTPSA id h8-20020a056830400800b005cdceb42261sm11904481ots.66.2022.04.10.20.13.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 10 Apr 2022 20:13:17 -0700 (PDT) Message-ID: <6296dc52-1298-6a52-a4fb-2c6fe04ab151@gmail.com> Date: Sun, 10 Apr 2022 22:13:16 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH for-next] RDMA/rxe: Fix "Replace red-black trees by xarrays" Content-Language: en-US To: Bart Van Assche , jgg@nvidia.com, zyjzyj2000@gmail.com, linux-rdma@vger.kernel.org, linux-scsi@vger.kernel.org, yi.zhang@redhat.com References: <20220410223939.3769-1-rpearsonhpe@gmail.com> From: Bob Pearson In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 4/10/22 22:06, Bart Van Assche wrote: > On 4/10/22 15:39, Bob Pearson wrote: >> Fixes: 3225717f6dfa ("RDMA/rxe: Replace red-black trees by carrays") >                                                              ^^^^^^^ >                                                              xarrays? > >> @@ -138,8 +140,10 @@ 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, >> +    xa_lock_irqsave(xa, flags); >> +    err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit, >>                     &pool->next, GFP_KERNEL); >> +    xa_unlock_irqrestore(xa, flags); > > Please take a look at the xas_unlock_type() and xas_lock_type() calls in __xas_nomem(). I think that the above change will trigger a GFP_KERNEL allocation with interrupts disabled. My understanding is that GFP_KERNEL allocations may sleep and hence that the above code may cause __xas_nomem() to sleep with interrupts disabled. I don't think that is allowed. > > Thanks, > > Bart. You're right. I missed that. Zhu wants to write the patch so hopefully he's on top of that. For now we could use GFP_ATOMIC. Bob