From: jing zhang Subject: Re: [PATCH] ext4: memory leakage in ext4_discard_preallocations Date: Fri, 26 Mar 2010 22:12:08 +0800 Message-ID: References: <20100318174629.GK8256@thunk.org> <67790F0F-9921-4A98-8DC6-DA1C00CE6CA9@sun.com> <87vdcjv5pw.fsf@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Andreas Dilger , tytso@mit.edu, linux-ext4 , Dave Kleikamp To: "Aneesh Kumar K. V" Return-path: Received: from mail-gw0-f46.google.com ([74.125.83.46]:37988 "EHLO mail-gw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753836Ab0CZOMJ (ORCPT ); Fri, 26 Mar 2010 10:12:09 -0400 Received: by gwaa18 with SMTP id a18so2790325gwa.19 for ; Fri, 26 Mar 2010 07:12:08 -0700 (PDT) In-Reply-To: <87vdcjv5pw.fsf@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 2010/3/26, Aneesh Kumar K. V : > On Sat, 20 Mar 2010 22:05:13 +0800, jing zhang wrote: >> >> Evening, >> >> Thanks Andreas and Ted for your good explanations to deal error in >> gentle way, and I got it that the chance may exist since the pa is not >> deleted from its group_list yet. >> >> And it also seems that there is work deserved. >> - zj >> >> --- >> >> --- linux-2.6.32/fs/ext4/mballoc.c 2009-12-03 11:51:22.000000000 +0800 >> +++ fs/mballoc.c 2010-03-20 21:40:04.000000000 +0800 >> @@ -3788,14 +3788,14 @@ repeat: >> err = ext4_mb_load_buddy(sb, group, &e4b); >> if (err) { >> ext4_error(sb, __func__, "Error in loading buddy " >> - "information for %u", group); >> + "information for group %u inode %lu", group, inode->i_ino); >> continue; >> } >> >> bitmap_bh = ext4_read_block_bitmap(sb, group); >> if (bitmap_bh == NULL) { >> ext4_error(sb, __func__, "Error in reading block " >> - "bitmap for %u", group); >> + "bitmap for group %u inode %lu", group, inode->i_ino); >> ext4_mb_release_desc(&e4b); >> continue; >> } >> @@ -3811,6 +3811,14 @@ repeat: >> list_del(&pa->u.pa_tmp_list); >> call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback); >> } >> + if (! list_empty(&list)) { >> + /* >> + * we have to do something for the check in >> + * the function, ext4_mb_discard_group_preallocations() >> + */ >> + list_for_each_entry(pa, &list, u.pa_tmp_list) >> + pa->pa_deleted = 0; >> + } >> if (ac) >> kmem_cache_free(ext4_ac_cachep, ac); >> } > > Can you add a comment saying if we fail to load buddy or read block > bitmap we skip freeing the prealloc space. So mark it undeleted. The > prealloc space is still removed from the inode but it is linked to the > group prealloc list via (pa_group_list) > > > -aneesh > /* * here the tricky is to mark PAs undeleted, * since they are still on their pa_group_list. */ That is it, Aneesh. I am still waiting for comments, if any, from Ted, since I am not sure the tricky is safe enough. And I am able not to deliver better patch tonight :( - zj