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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 6D04BC4360D for ; Mon, 9 Sep 2019 03:05:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47CEE21928 for ; Mon, 9 Sep 2019 03:05:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733271AbfIIDEC (ORCPT ); Sun, 8 Sep 2019 23:04:02 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:2175 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731489AbfIIDEB (ORCPT ); Sun, 8 Sep 2019 23:04:01 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 028B022A813B78DC2CC7; Mon, 9 Sep 2019 11:03:58 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.207) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 9 Sep 2019 11:03:54 +0800 Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: avoid infinite GC loop due to stale atomic files To: Jaegeuk Kim , , References: <20190909012532.20454-1-jaegeuk@kernel.org> <20190909012532.20454-2-jaegeuk@kernel.org> From: Chao Yu Message-ID: Date: Mon, 9 Sep 2019 11:03:43 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190909012532.20454-2-jaegeuk@kernel.org> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/9/9 9:25, Jaegeuk Kim wrote: > If committing atomic pages is failed when doing f2fs_do_sync_file(), we can > get commited pages but atomic_file being still set like: > > - inmem: 0, atomic IO: 4 (Max. 10), volatile IO: 0 (Max. 0) > > If GC selects this block, we can get an infinite loop like this: > > f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8, oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA > f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA, sector = 18533696, size = 4096 > f2fs_get_victim: dev = (253,7), type = No TYPE, policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1, ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234 > f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0, i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c > f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8, oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA > f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA, sector = 18533696, size = 4096 > f2fs_get_victim: dev = (253,7), type = No TYPE, policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1, ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234 > f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0, i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c > > In that moment, we can observe: > > [Before] > Try to move 5084219 blocks (BG: 384508) > - data blocks : 4962373 (274483) > - node blocks : 121846 (110025) > Skipped : atomic write 4534686 (10) > > [After] > Try to move 5088973 blocks (BG: 384508) > - data blocks : 4967127 (274483) > - node blocks : 121846 (110025) > Skipped : atomic write 4539440 (10) > > Signed-off-by: Jaegeuk Kim > --- > fs/f2fs/file.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index 7ae2f3bd8c2f..68b6da734e5f 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -1997,11 +1997,11 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp) > goto err_out; > > ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true); > - if (!ret) { > - clear_inode_flag(inode, FI_ATOMIC_FILE); > - F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > - stat_dec_atomic_write(inode); > - } > + > + /* doesn't need to check error */ > + clear_inode_flag(inode, FI_ATOMIC_FILE); > + F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > + stat_dec_atomic_write(inode); If there are still valid atomic write pages linked in .inmem_pages, it may cause memory leak when we just clear FI_ATOMIC_FILE flag. So my question is why below logic didn't handle such condition well? f2fs_gc() if (has_not_enough_free_secs(sbi, sec_freed, 0)) { if (skipped_round <= MAX_SKIP_GC_COUNT || skipped_round * 2 < round) { segno = NULL_SEGNO; goto gc_more; } if (first_skipped < last_skipped && (last_skipped - first_skipped) > sbi->skipped_gc_rwsem) { f2fs_drop_inmem_pages_all(sbi, true); segno = NULL_SEGNO; goto gc_more; } if (gc_type == FG_GC && !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) ret = f2fs_write_checkpoint(sbi, &cpc); } > } else { > ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false); > } >