From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7CAAC6D1BC for ; Tue, 16 Apr 2024 12:06:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713269209; cv=none; b=c0MGUfGRYo9BfKsRfu/B/X5KGk5nRO3Qcuuae7fRW4a9xs1hOT+UlkscZe1ivCmK8EazeAIQPEnxJny3A4S0EsHMJpVh8u1voiuVQHOGCN4mAr4PGN/nf8LpfdQc7bvJ/BJQuNQ7Ca9IuAf+1IWZ882DQFsvjtz4wsxtTrLFVjE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713269209; c=relaxed/simple; bh=L3gLHmGR54K6SZNtYN6NHQ8Yv2YeQe4FVtPT6weNbkM=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=ul950lqNx0aPYEueq/CUY03nR5nkR5H/sAgPGDwWX7faT+zm5Dhheb2a5PcXpDuUNdNEa77kTkuWukRH0zO+yd4MUWnRx+V+HjVBf0lEzpQkHGI6YoNAFncGHil95n8UdTGMDFhifPXeratgbExv9zW+gerIu3eh5vL39M/vZ50= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=I9Yd1l6y; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="I9Yd1l6y" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1713269207; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=TqRKbpNBE+kprBkHiETijO6t8ioX2KMP2NFaEORNgog=; b=I9Yd1l6yUPqyojmJ8j1L52TJfSzP6hJnm1WioVA0oDTmWY7oT43zLtyuDIV4eEBLuzKUJH S2T0fJ5+xykB2on0DugJsy2QaZc8IxMUjoBIcAodiMx4AUG/wdZIOm+3zqxWeOF9q1d2Zi C61EkzDfNIfxHRW9b/PqqW+Kpgs3BGE= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-116-rRNffDF0PLaVx1eJUgSPsQ-1; Tue, 16 Apr 2024 08:06:45 -0400 X-MC-Unique: rRNffDF0PLaVx1eJUgSPsQ-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-343edd4ac01so925721f8f.0 for ; Tue, 16 Apr 2024 05:06:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713269204; x=1713874004; h=mime-version:user-agent:content-transfer-encoding:autocrypt :references:in-reply-to:date:cc:to:from:subject:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=TqRKbpNBE+kprBkHiETijO6t8ioX2KMP2NFaEORNgog=; b=sQcVVmM2fhGLiCnfwCthqe8bi9xSWvQm8XmMCl7YWwD/1jWW/t+rI7qbu10dCNQ99g rpWTwxQx4c5N+5zjaOc5zjZF0O6eNA8/RbXDfqtIh/zGoXT7KrbGOPPVk5nykzqnOI9k yFinca2YqTVHQDRIfFzvb5uAL7xCHHk9joejkcLm3unsrEeAinFYCvBUPCUZm5IbCzcS Hk8cOYvsAjSY/VgC75GC/nI8L27yp3E2p0JXweUxRscJRGrZAdgy70H8iBeBpXh17P6p KXpU0qivLMq1p63W75FjhLOZ3RW9dNEQg780lm1RflyRWQv8Xyx8KT8h8w2JeEaDr5i+ pogg== X-Forwarded-Encrypted: i=1; AJvYcCXPrBIcGGqa9nZIA7p0q1auh6LUBW9B8qGvezkeJedagC3mDNsR8HVg/JE1tzelIa5Q8Lt3EYclFz1ZMH8HMMir+k1t7nWO X-Gm-Message-State: AOJu0YzcegCuPFE7IhcY8/Rm48aEP/w4kuyAzywfrTcxM+tc38TndziN nvQ2nvb/k04Q1ouCWFGc0hHdKOJhj1/FpCZTcDkLVO2jzauakXdSjGeWtYkiDOeiAFgi5ZEoHeU DSLXGsywVea8YfznZECDYnNVfklB+pZF3KRJPuqBVGDXjff14xKiIAQ== X-Received: by 2002:a05:600c:3556:b0:418:3cf7:7f7b with SMTP id i22-20020a05600c355600b004183cf77f7bmr5411899wmq.3.1713269204727; Tue, 16 Apr 2024 05:06:44 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFp9e8u/HJoCPvdDm1tdgrLn9iFLeuSuJJQGxRhAu4E1tl/xynojmx7/RiaY9ChbsAR72lJDA== X-Received: by 2002:a05:600c:3556:b0:418:3cf7:7f7b with SMTP id i22-20020a05600c355600b004183cf77f7bmr5411886wmq.3.1713269204369; Tue, 16 Apr 2024 05:06:44 -0700 (PDT) Received: from gerbillo.redhat.com (146-241-231-31.dyn.eolo.it. [146.241.231.31]) by smtp.gmail.com with ESMTPSA id g13-20020a05600c4ecd00b004148d7b889asm23021219wmq.8.2024.04.16.05.06.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Apr 2024 05:06:43 -0700 (PDT) Message-ID: Subject: Re: [PATCH net] net/smc: fix potential sleeping issue in smc_switch_conns From: Paolo Abeni To: Zhengchao Shao , linux-s390@vger.kernel.org, netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org Cc: wenjia@linux.ibm.com, jaka@linux.ibm.com, alibuda@linux.alibaba.com, tonylu@linux.alibaba.com, guwen@linux.alibaba.com, weiyongjun1@huawei.com, yuehaibing@huawei.com, tangchengchang@huawei.com Date: Tue, 16 Apr 2024 14:06:42 +0200 In-Reply-To: <20240413035150.3338977-1-shaozhengchao@huawei.com> References: <20240413035150.3338977-1-shaozhengchao@huawei.com> Autocrypt: addr=pabeni@redhat.com; prefer-encrypt=mutual; keydata=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 7ZxN9ZsDL38qVIuFkSpgMZCiUHdxBC11J8nbBSLlpnc924UAyr5XrGA99 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 iWjoCy8L35zPqR5TV+f5WR5hTVCqmLHSgm1jxwKhPg9L+GfuE4d0SWd84y 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 sD2W1U7eyLdm/jCgticGDsRtweytsgCSYfbz0gdgUuL3EBYN3JLbAU+UZpy 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.4 (3.50.4-1.fc39) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sat, 2024-04-13 at 11:51 +0800, Zhengchao Shao wrote: > Potential sleeping issue exists in the following processes: > smc_switch_conns > spin_lock_bh(&conn->send_lock) > smc_switch_link_and_count > smcr_link_put > __smcr_link_clear > smc_lgr_put > __smc_lgr_free > smc_lgr_free_bufs > __smc_lgr_free_bufs > smc_buf_free > smcr_buf_free > smcr_buf_unmap_link > smc_ib_put_memory_region > ib_dereg_mr > ib_dereg_mr_user > mr->device->ops.dereg_mr > If scheduling exists when the IB driver implements .dereg_mr hook > function, the bug "scheduling while atomic" will occur. For example, > cxgb4 and efa driver. Use mutex lock instead of spin lock to fix it. I tried to inspect all the lock call sites, and it *look* like they are all in process context, so the switch should be feasible. Still the fact that the existing lock is a BH variant is suspect. Either the BH part was not needed or this can introduce subtle regressions/issues.=20 I think this deserves at least a 3rd party testing. Thanks, Paolo