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Date: Wed, 10 Feb 2021 12:00:02 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: kbuild@...ts.01.org,
Harshad Shirwadkar <harshadshirwadkar@...il.com>,
linux-ext4@...r.kernel.org
Cc: lkp@...el.com, kbuild-all@...ts.01.org, tytso@....edu,
bzzz@...mcloud.com, artem.blagodarenko@...il.com, sihara@....com,
adilger@...ger.ca, Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: [kbuild] Re: [PATCH v2 4/5] ext4: improve cr 0 / cr 1 group scanning
Hi Harshad,
url: https://github.com/0day-ci/linux/commits/Harshad-Shirwadkar/ext4-drop-s_mb_bal_lock-and-convert-protected-fields-to-atomic/20210210-054647
base: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: s390-randconfig-m031-20210209 (attached as .config)
compiler: s390-linux-gcc (GCC) 9.3.0
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
New smatch warnings:
fs/ext4/mballoc.c:930 ext4_mb_choose_next_group_cr1() error: uninitialized symbol 'avg_fragment_size'.
vim +/avg_fragment_size +930 fs/ext4/mballoc.c
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 878 static int ext4_mb_choose_next_group_cr1(struct ext4_allocation_context *ac,
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 879 int *new_cr, ext4_group_t *group, ext4_group_t ngroups)
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 880 {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 881 struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 882 int avg_fragment_size, best_so_far;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 883 struct rb_node *node, *found;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 884 struct ext4_group_info *grp;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 885
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 886 /*
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 887 * If there is contention on the lock, instead of waiting for the lock
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 888 * to become available, just continue searching lineraly. We'll resume
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 889 * our rb tree search later starting at ac->ac_last_optimal_group.
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 890 */
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 891 if (!read_trylock(&sbi->s_mb_rb_lock))
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 892 return 1;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 893
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 894 if (ac->ac_flags & EXT4_MB_CR1_OPTIMIZED) {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 895 /* We have found something at CR 1 in the past */
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 896 grp = ext4_get_group_info(ac->ac_sb, ac->ac_last_optimal_group);
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 897 for (found = rb_next(&grp->bb_avg_fragment_size_rb); found != NULL;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 898 found = rb_next(found)) {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 899 grp = rb_entry(found, struct ext4_group_info,
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 900 bb_avg_fragment_size_rb);
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 901 /*
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 902 * Perform this check without locking, we'll lock later
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 903 * to confirm.
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 904 */
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 905 if (likely(ext4_mb_good_group(ac, grp->bb_group, 1)))
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 906 break;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 907 }
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 908
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 909 goto done;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 910 }
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 911
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 912 node = sbi->s_mb_avg_fragment_size_root.rb_node;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 913 best_so_far = 0;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 914 found = NULL;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 915
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 916 while (node) {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 917 grp = rb_entry(node, struct ext4_group_info,
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 918 bb_avg_fragment_size_rb);
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 919 /*
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 920 * Perform this check without locking, we'll lock later to confirm.
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 921 */
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 922 if (ext4_mb_good_group(ac, grp->bb_group, 1)) {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 923 avg_fragment_size = grp->bb_fragments ?
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 924 grp->bb_free / grp->bb_fragments : 0;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 925 if (!best_so_far || avg_fragment_size < best_so_far) {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 926 best_so_far = avg_fragment_size;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 927 found = node;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 928 }
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 929 }
avg_fragment_size not initialized on else path.
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 @930 if (avg_fragment_size > ac->ac_g_ex.fe_len)
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 931 node = node->rb_right;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 932 else
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 933 node = node->rb_left;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 934 }
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 935
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 936 done:
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 937 if (found) {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 938 grp = rb_entry(found, struct ext4_group_info,
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 939 bb_avg_fragment_size_rb);
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 940 *group = grp->bb_group;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 941 ac->ac_flags |= EXT4_MB_CR1_OPTIMIZED;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 942 } else {
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 943 *new_cr = 2;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 944 }
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 945
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 946 read_unlock(&sbi->s_mb_rb_lock);
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 947 ac->ac_last_optimal_group = *group;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 948 return 0;
ef4eebad9c018a Harshad Shirwadkar 2021-02-09 949 }
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Download attachment ".config.gz" of type "application/gzip" (28871 bytes)
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