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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E465EC38145 for ; Thu, 8 Sep 2022 11:34:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231438AbiIHLeD (ORCPT ); Thu, 8 Sep 2022 07:34:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35392 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231443AbiIHLeA (ORCPT ); Thu, 8 Sep 2022 07:34:00 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FEF6112E74 for ; Thu, 8 Sep 2022 04:33:56 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 2CBEF33698; 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Thu, 8 Sep 2022 11:33:55 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id HSNnByPTGWMCBQAAMHmgww (envelope-from ); Thu, 08 Sep 2022 11:33:55 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 9CC37A067E; Thu, 8 Sep 2022 13:33:54 +0200 (CEST) Date: Thu, 8 Sep 2022 13:33:54 +0200 From: Jan Kara To: Dan Carpenter Cc: kbuild@lists.01.org, Jan Kara , Ted Tso , lkp@intel.com, kbuild-all@lists.01.org, linux-ext4@vger.kernel.org, Thorsten Leemhuis , Ojaswin Mujoo , Stefan Wahren , Andreas Dilger Subject: Re: [PATCH 5/5] ext4: Use buckets for cr 1 block scan instead of rbtree Message-ID: <20220908113354.uikvfzlv7sn4a6iw@quack3> References: <20220906152920.25584-5-jack@suse.cz> <202209071206.u1iHKVzB-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202209071206.u1iHKVzB-lkp@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu 08-09-22 14:00:17, Dan Carpenter wrote: > Hi Jan, > > https://git-scm.com/docs/git-format-patch#_base_tree_information] > > url: https://github.com/intel-lab-lkp/linux/commits/Jan-Kara/ext4-Fix-performance-regression-with-mballoc/20220907-000945 > base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 53e99dcff61e1523ec1c3628b2d564ba15d32eb7 > config: m68k-randconfig-m041-20220906 (https://download.01.org/0day-ci/archive/20220907/202209071206.u1iHKVzB-lkp@intel.com/config) > compiler: m68k-linux-gcc (GCC) 12.1.0 > > If you fix the issue, kindly add following tag where applicable > Reported-by: kernel test robot > Reported-by: Dan Carpenter > > New smatch warnings: > fs/ext4/mballoc.c:945 ext4_mb_choose_next_group_cr1() error: uninitialized symbol 'grp'. > > vim +/grp +945 fs/ext4/mballoc.c > > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 909 static void ext4_mb_choose_next_group_cr1(struct ext4_allocation_context *ac, > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 910 int *new_cr, ext4_group_t *group, ext4_group_t ngroups) > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 911 { > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 912 struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); > 31b571b608cf66 Jan Kara 2022-09-06 913 struct ext4_group_info *grp, *iter; > 31b571b608cf66 Jan Kara 2022-09-06 914 int i; > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 915 > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 916 if (unlikely(ac->ac_flags & EXT4_MB_CR1_OPTIMIZED)) { > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 917 if (sbi->s_mb_stats) > 196e402adf2e4c Harshad Shirwadkar 2021-04-01 918 atomic_inc(&sbi->s_bal_cr1_bad_suggestions); > 31b571b608cf66 Jan Kara 2022-09-06 919 } > 31b571b608cf66 Jan Kara 2022-09-06 920 > 31b571b608cf66 Jan Kara 2022-09-06 921 for (i = mb_avg_fragment_size_order(ac->ac_sb, ac->ac_g_ex.fe_len); > 31b571b608cf66 Jan Kara 2022-09-06 922 i < MB_NUM_ORDERS(ac->ac_sb); i++) { > 31b571b608cf66 Jan Kara 2022-09-06 923 if (list_empty(&sbi->s_mb_avg_fragment_size[i])) > 31b571b608cf66 Jan Kara 2022-09-06 924 continue; > 31b571b608cf66 Jan Kara 2022-09-06 925 read_lock(&sbi->s_mb_avg_fragment_size_locks[i]); > 31b571b608cf66 Jan Kara 2022-09-06 926 if (list_empty(&sbi->s_mb_avg_fragment_size[i])) { > 31b571b608cf66 Jan Kara 2022-09-06 927 read_unlock(&sbi->s_mb_largest_free_orders_locks[i]); > 31b571b608cf66 Jan Kara 2022-09-06 928 continue; > > Smatch worries that we can hit these two continues on every iteration. > Why not just initialize "grp = NULL;" at the start of the function? Yes, good point. It may even be possible in some rare racy cornercase. I'll do what you suggest. Thanks! Honza -- Jan Kara SUSE Labs, CR