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dkim=fail reason="signature verification failed" (1024-bit key) header.d=sf.net header.i=@sf.net header.b="R0m7iycn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 024DE20717 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-f2fs-devel-bounces@lists.sourceforge.net Received: from [127.0.0.1] (helo=sfs-ml-4.v29.lw.sourceforge.com) by sfs-ml-4.v29.lw.sourceforge.com with esmtp (Exim 4.90_1) (envelope-from ) id 1hvClR-0002Xp-IJ; Wed, 07 Aug 2019 03:37:25 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-4.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hvClQ-0002Xi-QT for linux-f2fs-devel@lists.sourceforge.net; Wed, 07 Aug 2019 03:37:24 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:CC:To:Subject:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; 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Wed, 07 Aug 2019 03:37:24 +0000 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 8CB201ACE2B478DE5047; Wed, 7 Aug 2019 11:37:13 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.213) with Microsoft SMTP Server (TLS) id 14.3.439.0; Wed, 7 Aug 2019 11:37:08 +0800 To: Sahitya Tummala References: <1565090396-7263-1-git-send-email-stummala@codeaurora.org> <8766875c-1e35-22dc-48d2-45b6776e4f38@huawei.com> <20190807032458.GI8289@codeaurora.org> From: Chao Yu Message-ID: <28512520-d8fe-839f-67ab-45f89f12968d@huawei.com> Date: Wed, 7 Aug 2019 11:37:22 +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: <20190807032458.GI8289@codeaurora.org> Content-Language: en-US X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected X-Headers-End: 1hvClM-00E1ZC-MB Subject: Re: [f2fs-dev] [PATCH v2] f2fs: Fix indefinite loop in f2fs_gc() X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jaegeuk Kim , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net Hi Sahitya, On 2019/8/7 11:24, Sahitya Tummala wrote: > Hi Chao, > > On Wed, Aug 07, 2019 at 10:04:16AM +0800, Chao Yu wrote: >> Hi Sahitya, >> >> On 2019/8/6 19:19, Sahitya Tummala wrote: >>> Policy - Foreground GC, LFS and greedy GC mode. >>> >>> Under this policy, f2fs_gc() loops forever to GC as it doesn't have >>> enough free segements to proceed and thus it keeps calling gc_more >>> for the same victim segment. This can happen if the selected victim >>> segment could not be GC'd due to failed blkaddr validity check i.e. >>> is_alive() returns false for the blocks set in current validity map. >>> >>> Fix this by keeping track of such invalid segments and skip those >>> segments for selection in get_victim_by_default() to avoid endless >>> GC loop under such error scenarios. >>> >>> Signed-off-by: Sahitya Tummala >>> --- >>> v2: fix as per Chao's suggestion to handle this error case >>> >>> fs/f2fs/gc.c | 15 ++++++++++++++- >>> fs/f2fs/segment.c | 5 +++++ >>> fs/f2fs/segment.h | 3 +++ >>> 3 files changed, 22 insertions(+), 1 deletion(-) >>> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>> index 8974672..321a78a 100644 >>> --- a/fs/f2fs/gc.c >>> +++ b/fs/f2fs/gc.c >>> @@ -382,6 +382,14 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi, >>> nsearched++; >>> } >>> >>> + /* >>> + * skip selecting the invalid segno (that is failed due to block >>> + * validity check failed during GC) to avoid endless GC loop in >>> + * such cases. >>> + */ >>> + if (test_bit(segno, sm->invalid_segmap)) >>> + goto next; >>> + >>> secno = GET_SEC_FROM_SEG(sbi, segno); >>> >>> if (sec_usage_check(sbi, secno)) >>> @@ -975,6 +983,7 @@ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, >>> int off; >>> int phase = 0; >>> int submitted = 0; >>> + struct sit_info *sit_i = SIT_I(sbi); >>> >>> start_addr = START_BLOCK(sbi, segno); >>> >>> @@ -1008,8 +1017,12 @@ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, >>> } >>> >>> /* Get an inode by ino with checking validity */ >>> - if (!is_alive(sbi, entry, &dni, start_addr + off, &nofs)) >>> + if (!is_alive(sbi, entry, &dni, start_addr + off, &nofs)) { >>> + if (!test_and_set_bit(segno, sit_i->invalid_segmap)) >>> + f2fs_err(sbi, "invalid blkaddr %u in seg %u is found\n", >>> + start_addr + off, segno); >> >> Oh, there is some normal cases in is_alive(), such as f2fs_get_node_page() or >> f2fs_get_node_info() failure due to no memory, we should bypass such cases. I > > Oh, yes, I have missed this point. > >> guess something like this: >> >> if (source_blkaddr != blkaddr) { >> if (unlikely(check_valid_map(sbi, segno, off))) { > > check_valid_map() is validated before is_alive(). So I think this check again > may not be needed. What do you think? > race in between is_alive() and update_sit_entry() There will be a race case: gc_data_segment f2fs_truncate_data_blocks_range check_valid_map f2fs_invalidate_blocks update_sit_entry f2fs_test_and_clear_bit(, se->cur_valid_map); unlock_page(node_page) is_alive lock_page(node_page) blkaddr should be NULL and not equal to source_blkaddr, I think this is a normal case, right? Thanks, > >> if (!test_and_set_bit(segno, sit_i->invalid_segmap)) { >> f2fs_err(sbi, "invalid blkaddr %u in seg %u is found\n", >> start_addr + off, segno); >> set_sbi_flag(sbi, SBI_NEED_FSCK); >> } >> } >> return false; >> } >> >> I think this will be safe to call check_valid_map(), because there should be no >> race in between is_alive() and update_sit_entry() from all paths due to node >> page lock dependence. >> >> One more concern is should we use this under CONFIG_F2FS_CHECK_FS? If there is >> actually such a bug can cause data inconsistency, we'd better find the root >> cause in debug version. >> > > Yes, I agree with you. I will include this under CONFIG_F2FS_CHECK_FS. > > Thanks, > >> Thanks, >> >>> continue; >>> + } >>> >>> if (phase == 2) { >>> f2fs_ra_node_page(sbi, dni.ino); >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >>> index a661ac3..d45a1d3 100644 >>> --- a/fs/f2fs/segment.c >>> +++ b/fs/f2fs/segment.c >>> @@ -4017,6 +4017,10 @@ static int build_sit_info(struct f2fs_sb_info *sbi) >>> return -ENOMEM; >>> #endif >>> >>> + sit_i->invalid_segmap = f2fs_kvzalloc(sbi, bitmap_size, GFP_KERNEL); >>> + if (!sit_i->invalid_segmap) >>> + return -ENOMEM; >>> + >>> /* init SIT information */ >>> sit_i->s_ops = &default_salloc_ops; >>> >>> @@ -4518,6 +4522,7 @@ static void destroy_sit_info(struct f2fs_sb_info *sbi) >>> #ifdef CONFIG_F2FS_CHECK_FS >>> kvfree(sit_i->sit_bitmap_mir); >>> #endif >>> + kvfree(sit_i->invalid_segmap); >>> kvfree(sit_i); >>> } >>> >>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h >>> index b746028..bc5dbe8 100644 >>> --- a/fs/f2fs/segment.h >>> +++ b/fs/f2fs/segment.h >>> @@ -246,6 +246,9 @@ struct sit_info { >>> unsigned long long min_mtime; /* min. modification time */ >>> unsigned long long max_mtime; /* max. modification time */ >>> >>> + /* list of segments to be ignored by GC in case of errors */ >>> + unsigned long *invalid_segmap; >>> + >>> unsigned int last_victim[MAX_GC_POLICY]; /* last victim segment # */ >>> }; >>> >>> > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel