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 X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B709EC43441 for ; Fri, 23 Nov 2018 11:03:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CA2820820 for ; Fri, 23 Nov 2018 11:03:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b="ryaooX5w" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7CA2820820 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=amarulasolutions.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409563AbeKWVqx (ORCPT ); Fri, 23 Nov 2018 16:46:53 -0500 Received: from mail-ed1-f67.google.com ([209.85.208.67]:45412 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2409549AbeKWVqw (ORCPT ); Fri, 23 Nov 2018 16:46:52 -0500 Received: by mail-ed1-f67.google.com with SMTP id d39so9898711edb.12 for ; Fri, 23 Nov 2018 03:03:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amarulasolutions.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=yhP3K5HcdfCAroFnskVcIMJwgZFxlm2bTaNNpGRRNuo=; b=ryaooX5wX3a9ydWWXNkvQO4MUpyhXUVZ5b+DARtO0BtVYhCNWm1APWnId9dyEEKgLq 4yaEBwZTcUDgFZ4gdaSbr4h9vP9sWPZoFs/ddlVR8aF9ayyhyZ1bM+XrOgPSZDuaQ8S2 7nKZzhULOjGX2gromiqauwNkKKEFwr1qkzqlM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=yhP3K5HcdfCAroFnskVcIMJwgZFxlm2bTaNNpGRRNuo=; b=T0R/ZgINCT9CwkMLjJdPTxQgvSDiD1IxO6C03Hbc3lXlmdb8gSsvY1kWIVYs2uTzhF /7tLbvqJdQS1m5KOLdTmqb+5FFkNrTt383K13byLDU1GiuylDTju6coM6L5iL9e3Vkdr OgeOpoNWqr8Qzi3atJW0JKGLL+jM1m15P+iJWVSd8UPyzAILIehQCM9eYRc3btxxVDGN 04ddIEDmDvY6jrpsA/eS1r37VHtZXaGHcUBAfBtMIbgpca97BabVl+NrnFdFXiiR0EKv AlPLbTRF/G0EQztSEmeImGFB220wWc+TB3dBW/wN+YwutENMHiBVXNKEV804MDfrM4uT ZiXA== X-Gm-Message-State: AGRZ1gJzwkNSSPLG6133bFwyy2cosfUgEae0jmPTiRm0bWwxFoVGBFs5 RcAGKJQ2eFT0UXtCSD0cHQmCYg== X-Google-Smtp-Source: AJdET5dPVQu9PmfOF6gU3yf5qrR63cEefAhKQsMXf85d7UURA4N3SWSLQ+9eoL4yByQjqYwFVJtlTg== X-Received: by 2002:a17:906:1353:: with SMTP id x19-v6mr11182468ejb.23.1542970982865; Fri, 23 Nov 2018 03:03:02 -0800 (PST) Received: from andrea (85.100.broadband17.iol.cz. [109.80.100.85]) by smtp.gmail.com with ESMTPSA id s19-v6sm2647240ejz.2.2018.11.23.03.03.01 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 23 Nov 2018 03:03:02 -0800 (PST) Date: Fri, 23 Nov 2018 12:02:55 +0100 From: Andrea Parri To: Sebastian Andrzej Siewior Cc: zhe.he@windriver.com, catalin.marinas@arm.com, tglx@linutronix.de, rostedt@goodmis.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, boqun.feng@gmail.com Subject: Re: [PATCH v2] kmemleak: Turn kmemleak_lock to raw spinlock on RT Message-ID: <20181123110226.GA5125@andrea> References: <1542877459-144382-1-git-send-email-zhe.he@windriver.com> <20181123095314.hervxkxtqoixovro@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181123095314.hervxkxtqoixovro@linutronix.de> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > is this an RT-only problem? Because mainline should not allow read->read > locking or read->write locking for reader-writer locks. If this only > happens on v4.18 and not on v4.19 then something must have fixed it. Probably misunderstanding, but I'd say that read->read locking is "the norm"...? If you don't use qrwlock, readers are also "recursive", in part., P0 P1 read_lock(l) write_lock(l) read_lock(l) won't block P0 on the second read_lock(). (qrwlock somehow complicate the analysis; IIUC, they are recursive if and only if in_interrupt().). Andrea > > > Sebastian