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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 06E4CC7618F for ; Fri, 19 Jul 2019 23:30:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8F8D21849 for ; Fri, 19 Jul 2019 23:30:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732913AbfGSXai (ORCPT ); Fri, 19 Jul 2019 19:30:38 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:41416 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728909AbfGSXai (ORCPT ); Fri, 19 Jul 2019 19:30:38 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1hocKe-0006qC-Fp; Fri, 19 Jul 2019 23:30:32 +0000 Date: Sat, 20 Jul 2019 00:30:32 +0100 From: Al Viro To: Jeff Layton Cc: Luis Henriques , Ilya Dryomov , Sage Weil , ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] ceph: fix buffer free while holding i_ceph_lock in __ceph_setxattr() Message-ID: <20190719233032.GB17978@ZenIV.linux.org.uk> References: <20190719143222.16058-1-lhenriques@suse.com> <20190719143222.16058-3-lhenriques@suse.com> <1dee14212043f12ef5b26e4aee0c3155e118abf3.camel@kernel.org> <20190719232307.GA17978@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190719232307.GA17978@ZenIV.linux.org.uk> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 20, 2019 at 12:23:08AM +0100, Al Viro wrote: > On Fri, Jul 19, 2019 at 07:07:49PM -0400, Jeff Layton wrote: > > > Al pointed out on IRC that vfree should be callable under spinlock. > > Al had been near-terminally low on caffeine at the time, posted > a retraction a few minutes later and went to grab some coffee... > > > It > > only sleeps if !in_interrupt(), and I think that should return true if > > we're holding a spinlock. > > It can be used from RCU callbacks and all such; it *can't* be used from > under spinlock - on non-preempt builds there's no way to recognize that. Re original patch: looks like the sane way to handle that. Alternatively, we could add kvfree_atomic() for use in such situations, but I rather doubt that it's a good idea - not unless you need to free something under a spinlock held over a large area, which is generally a bad idea to start with... Note that vfree_atomic() has only one caller in the entire tree, BTW.