From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932239AbcILVHU (ORCPT ); Mon, 12 Sep 2016 17:07:20 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50267 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756013AbcILVHQ (ORCPT ); Mon, 12 Sep 2016 17:07:16 -0400 Date: Mon, 12 Sep 2016 14:07:15 -0700 From: Andrew Morton To: Ian Kent Cc: Al Viro , Takashi Iwai , autofs mailing list , NeilBrown , Kernel Mailing List , linux-fsdevel Subject: Re: [PATCH] autofs - use dentry flags to block walks during expire Message-Id: <20160912140715.a56f7d696dec7acc19180025@linux-foundation.org> In-Reply-To: <20160912014017.1773.73060.stgit@pluto.themaw.net> References: <20160912014017.1773.73060.stgit@pluto.themaw.net> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 12 Sep 2016 09:40:17 +0800 Ian Kent wrote: > Somewhere along the way the autofs expire operation has changed to > hold a spin lock over expired dentry selection. The autofs indirect > mount expired dentry selection is complicated and quite lengthy so > it isn't appropriate to hold a spin lock over the operation. > > Commit 47be6184 added a might_sleep() to dput() causing a BUG() > about this usage to be issued. It's a WARN_ONCE(), not a BUG()? > But the spin lock doesn't need to be held over this check, the > autofs dentry info. flags are enough to block walks into dentrys > during the expire. > > I've left the direct mount expire as it is (for now) becuase it > is much simpler and quicker than the indirect mount expire and > adding spin lock release and re-aquires would do nothing more > than add overhead. > > Fixes: 47be61845c77 ("fs/dcache.c: avoid soft-lockup in dput()") > Signed-off-by: Ian Kent > Cc: Takashi Iwai > Cc: Andrew Morton > Cc: NeilBrown 47be61845c77 is cc:stable, so this should be likewise. I've made those two changes to my copy of this changelog. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH] autofs - use dentry flags to block walks during expire Date: Mon, 12 Sep 2016 14:07:15 -0700 Message-ID: <20160912140715.a56f7d696dec7acc19180025@linux-foundation.org> References: <20160912014017.1773.73060.stgit@pluto.themaw.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160912014017.1773.73060.stgit@pluto.themaw.net> Sender: autofs-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Ian Kent Cc: Al Viro , Takashi Iwai , autofs mailing list , NeilBrown , Kernel Mailing List , linux-fsdevel On Mon, 12 Sep 2016 09:40:17 +0800 Ian Kent wrote: > Somewhere along the way the autofs expire operation has changed to > hold a spin lock over expired dentry selection. The autofs indirect > mount expired dentry selection is complicated and quite lengthy so > it isn't appropriate to hold a spin lock over the operation. > > Commit 47be6184 added a might_sleep() to dput() causing a BUG() > about this usage to be issued. It's a WARN_ONCE(), not a BUG()? > But the spin lock doesn't need to be held over this check, the > autofs dentry info. flags are enough to block walks into dentrys > during the expire. > > I've left the direct mount expire as it is (for now) becuase it > is much simpler and quicker than the indirect mount expire and > adding spin lock release and re-aquires would do nothing more > than add overhead. > > Fixes: 47be61845c77 ("fs/dcache.c: avoid soft-lockup in dput()") > Signed-off-by: Ian Kent > Cc: Takashi Iwai > Cc: Andrew Morton > Cc: NeilBrown 47be61845c77 is cc:stable, so this should be likewise. I've made those two changes to my copy of this changelog. -- To unsubscribe from this list: send the line "unsubscribe autofs" in