From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id 9A6396B0035 for ; Mon, 30 Jun 2014 20:34:50 -0400 (EDT) Received: by mail-pa0-f43.google.com with SMTP id lf10so9574340pab.30 for ; Mon, 30 Jun 2014 17:34:50 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id yn4si24977467pac.38.2014.06.30.17.34.49 for ; Mon, 30 Jun 2014 17:34:49 -0700 (PDT) Date: Mon, 30 Jun 2014 17:34:28 -0700 From: Andrew Morton Subject: Re: [PATCH mmotm/next] mm: memcontrol: rewrite charge API: fix shmem_unuse Message-Id: <20140630173428.5ebeed18.akpm@linux-foundation.org> In-Reply-To: References: <20140630160212.46caf9c3d41445b61fece666@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Hugh Dickins Cc: Johannes Weiner , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Mon, 30 Jun 2014 17:10:54 -0700 (PDT) Hugh Dickins wrote: > On Mon, 30 Jun 2014, Andrew Morton wrote: > > On Mon, 30 Jun 2014 15:48:39 -0700 (PDT) Hugh Dickins wrote: > > > - return 0; > > > + return -EAGAIN; > > > > Maybe it's time to document the shmem_unuse_inode() return values. > > Oh dear. I had hoped they would look after themselves. This one is a > private matter between shmem_unuse_inode and its one caller, just below. Well, readers of shmem_unuse_inode() won't know that unless we tell them. > > > + if (error) { > > > + if (error != -ENOMEM) > > > + error = 0; > > > mem_cgroup_cancel_charge(page, memcg); > > > } else > > > mem_cgroup_commit_charge(page, memcg, true); > > > > If I'm reading this correctly, shmem_unuse() can now return -EAGAIN and > > that can get all the way back to userspace. `man 2 swapoff' doesn't > > know this... > > if (error) { > if (error != -ENOMEM) > error = 0; > ... > return error; > > So the only values returned from shmem_unuse_inode() to its caller > try_to_unuse() are 0 and -ENOMEM. Those may get passed back to the > user, but -EAGAIN was just an internal shmem.c detail. OK. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org