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Date: Thu, 11 Nov 2021 18:03:22 +0800
From: kernel test robot <yujie.liu@...el.com>
To: brookxu <brookxu.cn@...il.com>
CC: <llvm@...ts.linux.dev>, <kbuild-all@...ts.01.org>,
<linux-ext4@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] ext4: fix a possible ABBA deadlock dued to busy PA
Hi Chunguang,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on tytso-ext4/dev]
[also build test WARNING on v5.15 next-20211109]
[cannot apply to tytso-fscrypt/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/brookxu/ext4-fix-a-possible-ABBA-deadlock-dued-to-busy-PA/20210929-091410
base: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: i386-randconfig-c001-20210929 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project dc6e8dfdfe7efecfda318d43a06fae18b40eb498)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/5e956ecab47126f1d065a1ac6e6d5077e02e6f87
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review brookxu/ext4-fix-a-possible-ABBA-deadlock-dued-to-busy-PA/20210929-091410
git checkout 5e956ecab47126f1d065a1ac6e6d5077e02e6f87
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=i386 clang-analyzer
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>
clang-analyzer warnings: (new ones prefixed by >>)
>> fs/ext4/mballoc.c:4849:3: warning: Value stored to 'needed' is never read [clang-analyzer-deadcode.DeadStores]
needed = EXT4_CLUSTERS_PER_GROUP(sb) + 1;
^
vim +/needed +4849 fs/ext4/mballoc.c
c9de560ded61faa Alex Tomas 2008-01-29 4805
c9de560ded61faa Alex Tomas 2008-01-29 4806 /*
c9de560ded61faa Alex Tomas 2008-01-29 4807 * releases all preallocations in given group
c9de560ded61faa Alex Tomas 2008-01-29 4808 *
c9de560ded61faa Alex Tomas 2008-01-29 4809 * first, we need to decide discard policy:
c9de560ded61faa Alex Tomas 2008-01-29 4810 * - when do we discard
c9de560ded61faa Alex Tomas 2008-01-29 4811 * 1) ENOSPC
c9de560ded61faa Alex Tomas 2008-01-29 4812 * - how many do we discard
c9de560ded61faa Alex Tomas 2008-01-29 4813 * 1) how many requested
c9de560ded61faa Alex Tomas 2008-01-29 4814 */
4ddfef7b41aebbb Eric Sandeen 2008-04-29 4815 static noinline_for_stack int
4ddfef7b41aebbb Eric Sandeen 2008-04-29 4816 ext4_mb_discard_group_preallocations(struct super_block *sb,
5e956ecab47126f Chunguang Xu 2021-09-29 4817 ext4_group_t group, int needed, int *busy)
c9de560ded61faa Alex Tomas 2008-01-29 4818 {
c9de560ded61faa Alex Tomas 2008-01-29 4819 struct ext4_group_info *grp = ext4_get_group_info(sb, group);
c9de560ded61faa Alex Tomas 2008-01-29 4820 struct buffer_head *bitmap_bh = NULL;
c9de560ded61faa Alex Tomas 2008-01-29 4821 struct ext4_prealloc_space *pa, *tmp;
c9de560ded61faa Alex Tomas 2008-01-29 4822 struct list_head list;
c9de560ded61faa Alex Tomas 2008-01-29 4823 struct ext4_buddy e4b;
c9de560ded61faa Alex Tomas 2008-01-29 4824 int err;
5e956ecab47126f Chunguang Xu 2021-09-29 4825 int free = 0;
c9de560ded61faa Alex Tomas 2008-01-29 4826
d3df14535f4a5b5 Ritesh Harjani 2020-05-10 4827 mb_debug(sb, "discard preallocation for group %u\n", group);
c9de560ded61faa Alex Tomas 2008-01-29 4828 if (list_empty(&grp->bb_prealloc_list))
bbc4ec77e9f9c7a Ritesh Harjani 2020-05-10 4829 goto out_dbg;
c9de560ded61faa Alex Tomas 2008-01-29 4830
574ca174c97f790 Theodore Ts'o 2008-07-11 4831 bitmap_bh = ext4_read_block_bitmap(sb, group);
9008a58e5dcee01 Darrick J. Wong 2015-10-17 4832 if (IS_ERR(bitmap_bh)) {
9008a58e5dcee01 Darrick J. Wong 2015-10-17 4833 err = PTR_ERR(bitmap_bh);
54d3adbc29f0c7c Theodore Ts'o 2020-03-28 4834 ext4_error_err(sb, -err,
54d3adbc29f0c7c Theodore Ts'o 2020-03-28 4835 "Error %d reading block bitmap for %u",
9008a58e5dcee01 Darrick J. Wong 2015-10-17 4836 err, group);
bbc4ec77e9f9c7a Ritesh Harjani 2020-05-10 4837 goto out_dbg;
c9de560ded61faa Alex Tomas 2008-01-29 4838 }
c9de560ded61faa Alex Tomas 2008-01-29 4839
c9de560ded61faa Alex Tomas 2008-01-29 4840 err = ext4_mb_load_buddy(sb, group, &e4b);
ce89f46cb833f89 Aneesh Kumar K.V 2008-07-23 4841 if (err) {
9651e6b2e20648d Konstantin Khlebnikov 2017-05-21 4842 ext4_warning(sb, "Error %d loading buddy information for %u",
9651e6b2e20648d Konstantin Khlebnikov 2017-05-21 4843 err, group);
ce89f46cb833f89 Aneesh Kumar K.V 2008-07-23 4844 put_bh(bitmap_bh);
bbc4ec77e9f9c7a Ritesh Harjani 2020-05-10 4845 goto out_dbg;
ce89f46cb833f89 Aneesh Kumar K.V 2008-07-23 4846 }
c9de560ded61faa Alex Tomas 2008-01-29 4847
c9de560ded61faa Alex Tomas 2008-01-29 4848 if (needed == 0)
7137d7a48e2213e Theodore Ts'o 2011-09-09 @4849 needed = EXT4_CLUSTERS_PER_GROUP(sb) + 1;
c9de560ded61faa Alex Tomas 2008-01-29 4850
c9de560ded61faa Alex Tomas 2008-01-29 4851 INIT_LIST_HEAD(&list);
c9de560ded61faa Alex Tomas 2008-01-29 4852 ext4_lock_group(sb, group);
c9de560ded61faa Alex Tomas 2008-01-29 4853 list_for_each_entry_safe(pa, tmp,
c9de560ded61faa Alex Tomas 2008-01-29 4854 &grp->bb_prealloc_list, pa_group_list) {
c9de560ded61faa Alex Tomas 2008-01-29 4855 spin_lock(&pa->pa_lock);
c9de560ded61faa Alex Tomas 2008-01-29 4856 if (atomic_read(&pa->pa_count)) {
c9de560ded61faa Alex Tomas 2008-01-29 4857 spin_unlock(&pa->pa_lock);
5e956ecab47126f Chunguang Xu 2021-09-29 4858 *busy = 1;
c9de560ded61faa Alex Tomas 2008-01-29 4859 continue;
c9de560ded61faa Alex Tomas 2008-01-29 4860 }
c9de560ded61faa Alex Tomas 2008-01-29 4861 if (pa->pa_deleted) {
c9de560ded61faa Alex Tomas 2008-01-29 4862 spin_unlock(&pa->pa_lock);
c9de560ded61faa Alex Tomas 2008-01-29 4863 continue;
c9de560ded61faa Alex Tomas 2008-01-29 4864 }
c9de560ded61faa Alex Tomas 2008-01-29 4865
c9de560ded61faa Alex Tomas 2008-01-29 4866 /* seems this one can be freed ... */
27bc446e2def38d brookxu 2020-08-17 4867 ext4_mb_mark_pa_deleted(sb, pa);
c9de560ded61faa Alex Tomas 2008-01-29 4868
70022da804f0f3f Ye Bin 2020-09-16 4869 if (!free)
70022da804f0f3f Ye Bin 2020-09-16 4870 this_cpu_inc(discard_pa_seq);
70022da804f0f3f Ye Bin 2020-09-16 4871
c9de560ded61faa Alex Tomas 2008-01-29 4872 /* we can trust pa_free ... */
c9de560ded61faa Alex Tomas 2008-01-29 4873 free += pa->pa_free;
c9de560ded61faa Alex Tomas 2008-01-29 4874
c9de560ded61faa Alex Tomas 2008-01-29 4875 spin_unlock(&pa->pa_lock);
c9de560ded61faa Alex Tomas 2008-01-29 4876
c9de560ded61faa Alex Tomas 2008-01-29 4877 list_del(&pa->pa_group_list);
c9de560ded61faa Alex Tomas 2008-01-29 4878 list_add(&pa->u.pa_tmp_list, &list);
c9de560ded61faa Alex Tomas 2008-01-29 4879 }
c9de560ded61faa Alex Tomas 2008-01-29 4880
c9de560ded61faa Alex Tomas 2008-01-29 4881 /* now free all selected PAs */
c9de560ded61faa Alex Tomas 2008-01-29 4882 list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
c9de560ded61faa Alex Tomas 2008-01-29 4883
c9de560ded61faa Alex Tomas 2008-01-29 4884 /* remove from object (inode or locality group) */
c9de560ded61faa Alex Tomas 2008-01-29 4885 spin_lock(pa->pa_obj_lock);
c9de560ded61faa Alex Tomas 2008-01-29 4886 list_del_rcu(&pa->pa_inode_list);
c9de560ded61faa Alex Tomas 2008-01-29 4887 spin_unlock(pa->pa_obj_lock);
c9de560ded61faa Alex Tomas 2008-01-29 4888
cc0fb9ad7dbc5a1 Aneesh Kumar K.V 2009-03-27 4889 if (pa->pa_type == MB_GROUP_PA)
3e1e5f501632460 Eric Sandeen 2010-10-27 4890 ext4_mb_release_group_pa(&e4b, pa);
c9de560ded61faa Alex Tomas 2008-01-29 4891 else
3e1e5f501632460 Eric Sandeen 2010-10-27 4892 ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa);
c9de560ded61faa Alex Tomas 2008-01-29 4893
c9de560ded61faa Alex Tomas 2008-01-29 4894 list_del(&pa->u.pa_tmp_list);
c9de560ded61faa Alex Tomas 2008-01-29 4895 call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
c9de560ded61faa Alex Tomas 2008-01-29 4896 }
c9de560ded61faa Alex Tomas 2008-01-29 4897
c9de560ded61faa Alex Tomas 2008-01-29 4898 ext4_unlock_group(sb, group);
e39e07fdfd98be8 Jing Zhang 2010-05-14 4899 ext4_mb_unload_buddy(&e4b);
c9de560ded61faa Alex Tomas 2008-01-29 4900 put_bh(bitmap_bh);
bbc4ec77e9f9c7a Ritesh Harjani 2020-05-10 4901 out_dbg:
d3df14535f4a5b5 Ritesh Harjani 2020-05-10 4902 mb_debug(sb, "discarded (%d) blocks preallocated for group %u bb_free (%d)\n",
5e956ecab47126f Chunguang Xu 2021-09-29 4903 free, group, grp->bb_free);
5e956ecab47126f Chunguang Xu 2021-09-29 4904 return free;
c9de560ded61faa Alex Tomas 2008-01-29 4905 }
c9de560ded61faa Alex Tomas 2008-01-29 4906
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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