From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (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 644853597A; Mon, 7 Jul 2025 20:49:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751921362; cv=none; b=qDX7GBO2Opzx56jBjJdW8QQ7PQV9zT+xcVIBJGoferlRJmGM8kprRRm8+3U2nPyQzb2hFq7C6FGMBqniIp9+RwfoCy+ha7EIWEogy6iFw0dlJ48Lv2sapgERRdJvOvbipQfp2sVEWsvK64mhrT1wj1m1bjLB2Xvu3a/a02nIHuo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751921362; c=relaxed/simple; bh=OPwYRsV2ja4jyraAWVchxj36SMa89ln97ao5fJsFkJI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XFRHmh2EeN4mHqM0Fy0Vdtl9s9DRh2xkX3zNEq2UnPLj1lLJ98JW4F+5UgSmIJPL52TWzBO9+Rbree4VlW4U1IyRdrcf1pvoYScmyIsr5/OLU9I9CwLR+3wCW+bL4RT0F/DPt4W2bWgGzwYy/hEkCzv+nROPRP6dk9NGNBHV+FQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=SFp8HQFZ; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="SFp8HQFZ" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=g0QMBx8KfGZY6hoKAphVq9VC9pOgKSRRzHza0BduFT8=; b=SFp8HQFZS9B6BcK7cJRTTGidpl 2yXK35INgDDJW82fCJRD5mNHWCUCOnHkZYmGyLfVMplP0dNWjjW2d3ld+FJ1u25gTTYATnUEyxQ+c HM5BHMx+PD1D/56MBBCe1/ZbcONdRV3XqyyQTfzDrpVAe8o4uWLq5+c1m36LID9Vt/Vkn/6y0bjqe Wn8N9b0+OxF+bozpsBPnRXUg/8HZwTz/Tm9Qkfo+0Jk92bOs5BDkHKKEbNxinHXDWncPdO7fEonDz 5OsF0SG45UiFFw99ftjXlJyUxLv9zvhV1wW8h414N0mC5qOOcWeosShyv6U4Y5UTLrbiEbNWYkM8v 0ivzN53w==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uYsm6-00000003jOm-34RN; Mon, 07 Jul 2025 20:49:18 +0000 Date: Mon, 7 Jul 2025 21:49:18 +0100 From: Al Viro To: Max Kellermann Cc: linux-fsdevel@vger.kernel.org, Christian Brauner , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 20/21] __dentry_kill(): new locking scheme Message-ID: <20250707204918.GK1880847@ZenIV> References: <20231124060422.576198-20-viro@zeniv.linux.org.uk> <20250707172956.GF1880847@ZenIV> <20250707180026.GG1880847@ZenIV> <20250707193115.GH1880847@ZenIV> <20250707203104.GJ1880847@ZenIV> 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: Sender: Al Viro On Mon, Jul 07, 2025 at 10:39:27PM +0200, Max Kellermann wrote: > > Busy loop here means that everything in the tree is either busy or already > > in process of being torn down *by* *another* *thread*. And that's already > > in process - not just selected for it (see collect2 in the same loop). > > The busy process isn't doing anything. All it does is busy-wait for > another task to complete the evict() call. A pointless waste of CPU > cycles. > > > The interesting question is what the other thread is doing... > > ceph_evict_inode() is waiting for the Ceph server to acknowledge a > pending I/O operation. Yes, but where does that ceph_evict_inode() come from? What's in its call chain? Is it several shrink_dcache_parent() fighting each other on the same tree, or...?