Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751861Ab2KSUvY (ORCPT ); Mon, 19 Nov 2012 15:51:24 -0500 Received: from mail.parknet.co.jp ([210.171.160.6]:33314 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751624Ab2KSUvW (ORCPT ); Mon, 19 Nov 2012 15:51:22 -0500 From: OGAWA Hirofumi To: Jan Kara Cc: Al Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: The bug of iput() removal from flusher thread? References: <8762541uyx.fsf@devron.myhome.or.jp> <873906vumh.fsf@devron.myhome.or.jp> <20121119145140.GA20532@quack.suse.cz> <20121119194102.GB20532@quack.suse.cz> Date: Tue, 20 Nov 2012 05:51:15 +0900 In-Reply-To: <20121119194102.GB20532@quack.suse.cz> (Jan Kara's message of "Mon, 19 Nov 2012 20:41:02 +0100") Message-ID: <87a9udtiyk.fsf@devron.myhome.or.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2474 Lines: 66 Jan Kara writes: >>From 4fdc5d9a66dfe0286ef4f4a7f53fd3b15086470f Mon Sep 17 00:00:00 2001 > From: Jan Kara > Date: Mon, 19 Nov 2012 20:01:16 +0100 > Subject: [PATCH] writeback: Put unused inodes to LRU after writeback completion > > Commit 169ebd90 removed iget-iput pair from inode writeback. As a side effect, > inodes that are dirty during iput_final() call won't be ever added to inode LRU > (iput_final() doesn't add dirty inodes to LRU and later when the inode is > cleaned there's noone to add the inode there). Thus inodes are effectively > unreclaimable until someone looks them up again. > > Practical effect of this bug is limited by the fact that inodes are > pinned by a dentry for long enough that the inode gets cleaned. But still > the bug can have nasty consequences leading up to OOM conditions under > certain circumstances. Following can easily reproduce the problem: > > for (( i = 0; i < 1000; i++ )); do > mkdir $i > for (( j = 0; j < 1000; j++ )); do > touch $i/$j > echo 2 > /proc/sys/vm/drop_caches > done > done > > then one needs to run 'sync; ls -lR' to make inodes reclaimable again. > > We fix the issue by inserting unused clean inodes into the LRU after writeback > finishes in inode_sync_complete(). > > CC: Al Viro > Reported-by: OGAWA Hirofumi > Signed-off-by: Jan Kara Need to Cc to stable@ > --- > fs/fs-writeback.c | 3 +++ > fs/inode.c | 2 +- > fs/internal.h | 1 + > 3 files changed, 5 insertions(+), 1 deletions(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index 51ea267..ed7613b 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -227,6 +227,9 @@ static void requeue_io(struct inode *inode, struct bdi_writeback *wb) > > static void inode_sync_complete(struct inode *inode) > { > + /* If inode is clean an unused, put it into LRU now. */ > + if (!(inode->i_state & I_DIRTY) && !atomic_read(&inode->i_count)) > + inode_lru_list_add(inode); IMHO, open coding this would be bad idea. And another one is I_REFERENCED. We really want to remove I_REFERENCED? Thanks. -- OGAWA Hirofumi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/