From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1143E1607B4; Fri, 24 Jan 2025 23:15:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737760534; cv=none; b=aLokQCWy40bojdSrCp9L1X8YvNGMUUuLDJAQZn44/eWpX+ffT5RXJx14ru5QmbYts7dfDTXsg+zeHtrrlcvVpaO34uieEaQ5u0BNyvZ2227OrnZxJw4A0JfNOA2y/ByUFB+cSmT1e7FVnAxz2DoztpuBUyz7o4Q85o2+OeScV+I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737760534; c=relaxed/simple; bh=WhGADjkrbCEjiSFeTveagOuG8tWA8lDXdBSKLQpAjlc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qBeWod1xghau87Gc9WTM5duWoEL8QJhXQbZlbg76y5CEY3saP+pKBVGob8V50wxRgLe3Bf0iuMveK+eDSgfdZEfq/aHQT0TQKuyq25A04XXC+ENnHgBsphBCFPlKAQh+sv7/4CIeeBhhF0qABUAP9UqwZRV4heSh0mR9phhBwrw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X+YMbEdv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="X+YMbEdv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C99DC4CED2; Fri, 24 Jan 2025 23:15:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737760533; bh=WhGADjkrbCEjiSFeTveagOuG8tWA8lDXdBSKLQpAjlc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=X+YMbEdvwOcWXpIwRTi1BZVtLp+9EtQJ+LQjum81Spiv03uYFa+YQOx9Z90Zm0Gga OcKiub03InXb7EDb15vU0Gu5pGt/VLAMuS16W8wUfL4MoQywtmSq///xs8+fM2QnNn DSgWkdBvlFETDIF4em8dY01d6NEKyvA3NRlgt9uKyPuQglw/u3gvM426dUjJuB8xzD 6cU2g2IdmhUdcIuD422TxaSbU8enbEAnUP3AMs0QRsC9A9fXBNyoHmajybZYnW9txQ z7713EL2FdUTgrLUw9b16+qCfFe3Jlso7Uq7sNrNJc07CXbTpUR3FJaHNvfYHQPGdh Yi4Z/10hRjZVA== Date: Fri, 24 Jan 2025 13:15:32 -1000 From: Tejun Heo To: Sebastian Andrzej Siewior Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Michal =?iso-8859-1?Q?Koutn=FD?= , "Paul E. McKenney" , Boqun Feng , Greg Kroah-Hartman , Hillf Danton , Johannes Weiner , Marco Elver , Zefan Li , tglx@linutronix.de Subject: Re: [PATCH v4 4/6] kernfs: Don't re-lock kernfs_root::kernfs_rwsem in kernfs_fop_readdir(). Message-ID: References: <20250124174614.866884-1-bigeasy@linutronix.de> <20250124174614.866884-5-bigeasy@linutronix.de> 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: <20250124174614.866884-5-bigeasy@linutronix.de> Hello, On Fri, Jan 24, 2025 at 06:46:12PM +0100, Sebastian Andrzej Siewior wrote: ... > to avoid holding a global lock during a page fault. The lock drop is > wrong since the support of renames and not a big burden since the lock > is no longer global. It's still a pretty big lock. Hopefully, at least name accesses can be converted to rcu protected ones later? > Don't re-acquire kernfs_root::kernfs_rwsem while copying the name to the > userpace buffer. > > Signed-off-by: Sebastian Andrzej Siewior Acked-by: Tejun Heo Thanks. -- tejun