Please, ignore this. Patch 2 has wrong description. On 06.03.2020 15:32, Kirill Tkhai wrote: > Here we have even worse race than in mainstream. > > https://jira.sw.ru/browse/PSBM-101798 > > Fixes: 86521524314e "ext4: replace ext4_kvmalloc() with kvmalloc()" > Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com> > --- > fs/ext4/super.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 7b77cabae690..3adeeb00f118 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -2196,7 +2196,7 @@ int ext4_alloc_group_desc_bh_array(struct super_block > *sb, ext4_group_t ngroup) > { > struct ext4_sb_info *sbi = EXT4_SB(sb); > unsigned long num_desc = DIV_ROUND_UP(ngroup, EXT4_DESC_PER_BLOCK(sb)); > - struct buffer_head **n_group_desc; > + struct buffer_head **o_group_desc, **n_group_desc; > > if (num_desc <= sbi->s_gdb_count) > return 0; > @@ -2208,11 +2208,13 @@ int ext4_alloc_group_desc_bh_array(struct super_block > *sb, ext4_group_t ngroup) > return -ENOMEM; > } > > - memcpy(n_group_desc, sbi->s_group_desc, > + o_group_desc = sbi->s_group_desc; > + memcpy(n_group_desc, o_group_desc, > sbi->s_gdb_count * sizeof(struct buffer_head *)); > - kvfree(sbi->s_group_desc); > + WRITE_ONCE(sbi->s_group_desc, n_group_desc); > > - sbi->s_group_desc = n_group_desc; > + /* FIXME: rcu is needed here. See ms commit 1d0c3924a92e */ > + kvfree(o_group_desc); > return 0; > } > > >
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