From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 04ECD1C7B6B for ; Tue, 20 Aug 2024 22:54:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724194449; cv=none; b=spH7C1Tm8EYpFdQah7ykofGIOutFESudDKH2SZyvnfLY1PSBI0FPmLRogD7AWGguddNaEEbE4xpjCy0p22jZlcP3ugN8cdvkXvethZUWxBSaWu/3/0o/M1Ru0YMDcyF+y5s8QpltCwy0W9DytPyTg47r2o6F9wUZ+c3fRdIxI94= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724194449; c=relaxed/simple; bh=r5lBv7Hz+onnRrx/pZsD/8RoMGEs43L7lo0uknauVmk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WgvAX4Veh9/8dhgkF1miDJKpNeYdBQzbex2/skINW7FHeg/BinlJZ0q/bFcaX6ZyC+C+AGPXnqG59GPT5tt43pMb7o9WkUNgF5n+zlfOnC/hvOcJ+LAp55895XsFg6reUP43u4G3Kkt9AhNFpSti2SSiXb/0am7x9MXehlUf3Mk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=DxCcwd0X; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="DxCcwd0X" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=lKAGCijiX0EyKGs0TgqDBYnrweM5givvvNYv/P0zrdo=; b=DxCcwd0XNiWUCcpNE2+lOPx3iy JM9HAeDo1J7YHZQZwFkiB7rV7Y48v3TxUDBokdamUSQvgieL/lbFhIzSYKONX4EnRmS9B+c/Kqlck ow8OYQ889KElsfnJfD1wd5x1JGDPszTspJ7dyy07LPzTU2yi0cCF6AofvaHH6zxsojLI8UfOGu5t/ zmDFciyvdIllLh+YVAmir08HGJlN+L0yT7sroB3xSgmMD4NKMFTY/UOzxXlovypoN7Hu7v9d//hkY hX8a1NMEla9WpHSutOIeMXujBjf0CAj1tj/hXOsEV9tDu6Zdji8+1MbXmQShaEGhs9xyKmqYEA1XT XW3PchxA==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sgXji-00000008UIL-2mMC; Tue, 20 Aug 2024 22:53:58 +0000 Date: Tue, 20 Aug 2024 23:53:58 +0100 From: Matthew Wilcox To: Hillf Danton Cc: "Liam R. Howlett" , Andrew Morton , maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Paul E. McKenney" , syzbot+036af2f0c7338a33b0cd@syzkaller.appspotmail.com Subject: Re: [PATCH] maple_tree: Remove rcu_read_lock() from mt_validate() Message-ID: References: <20240820175417.2782532-1-Liam.Howlett@oracle.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240820175417.2782532-1-Liam.Howlett@oracle.com> On Wed, Aug 21, 2024 at 06:38:45AM +0800, Hillf Danton wrote: Hillf, your email client is STILL broken. It's using the same message ID as the email it's replying to, which causes all kinds of problems. Please fix it or change to a different client. > On Tue, 20 Aug 2024 13:54:17 -0400 "Liam R. Howlett" > > > > The write lock should be held when validating the tree to avoid updates > > racing with checks. Holding the rcu read lock during a large tree > > validation may also cause a prolonged rcu read window. > > > >From the rcu stall's view, holding spin lock plays the same role of rcu > read lock, so what are you fixing by simply dropping rcu read lock? He's not holding a spinlock, he's holding a mutex, which has very different properties.