From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: The bug of iput() removal from flusher thread? Date: Mon, 19 Nov 2012 15:51:40 +0100 Message-ID: <20121119145140.GA20532@quack.suse.cz> References: <8762541uyx.fsf@devron.myhome.or.jp> <873906vumh.fsf@devron.myhome.or.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Al Viro , Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: OGAWA Hirofumi Return-path: Received: from cantor2.suse.de ([195.135.220.15]:52285 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751799Ab2KSOvq (ORCPT ); Mon, 19 Nov 2012 09:51:46 -0500 Content-Disposition: inline In-Reply-To: <873906vumh.fsf@devron.myhome.or.jp> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon 19-11-12 17:56:22, OGAWA Hirofumi wrote: > OGAWA Hirofumi writes: > > > Hi, > > > > In 169ebd90131b2ffca74bb2dbe7eeacd39fb83714 commit, writeback doesn't > > __iget()/iput() anymore. > > > > This means nobody moves the inode to lru list. I.e. > > > > new_inode() > > dirty_inode() > > iput_final() > > /* keep inode without adding lru */ > > flush indoes > > /* clean inode is not on lru */ > > > > I noticed this situation in my FS though, I think the same bug is on all > > FSes of linus tree too, after this commit. > > > > Am I missing the something? > > This seems to be reproducible by the following, > > #!/bin/sh > > for i in $(seq -w 1000); do > for j in $(seq -w 1000); do > for k in $(seq -w 1000); do > mkdir -p $i/$j > echo $i/$j/$k > $i/$j/$k > echo 2 > /proc/sys/vm/drop_caches > done > done > done > > Some inodes never be reclaimed, and ls -l frees those inodes (stat(2) > does iget/iput). So looking into the code I agree we won't put inode into the LRU when it is dirty or under writeback and after writeback is done it won't happen either. That's certainly a bug. But I have hard time reproducing your results because on my kernels even dcache doesn't get shrunk thus inodes are pinned in memory by it. Not sure what's going on yet but I'll investigate. Thanks for report! Honza -- Jan Kara SUSE Labs, CR