In ext4_put_super, we call brelse on the buffer head containing
the ext4 superblock, but then try to use it when we stop the
mmp thread, because when the thread shuts down it does:
write_mmp_block
ext4_mmp_csum_set
ext4_has_metadata_csum
WARN_ON_ONCE(ext4_has_feature_metadata_csum(sb)...)
which reaches into sb->s_fs_info->s_es->s_feature_ro_compat,
which lives in the superblock buffer s_sbh which we just released.
Fix this by moving the brelse down to a point where we are no
longer using it.
Reported-by: Wang Shu <[email protected]>
Signed-off-by: Eric Sandeen <[email protected]>
---
Note: found by inspection after a bug report via KASAN,
compile-tested only.
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6db81fb..f273212 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -862,7 +862,6 @@ static void ext4_put_super(struct super_block *sb)
percpu_counter_destroy(&sbi->s_dirs_counter);
percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
percpu_free_rwsem(&sbi->s_journal_flag_rwsem);
- brelse(sbi->s_sbh);
#ifdef CONFIG_QUOTA
for (i = 0; i < EXT4_MAXQUOTAS; i++)
kfree(sbi->s_qf_names[i]);
@@ -894,6 +893,9 @@ static void ext4_put_super(struct super_block *sb)
}
if (sbi->s_mmp_tsk)
kthread_stop(sbi->s_mmp_tsk);
+
+ /* Don't let this go until everything is done with the ext4 super */
+ brelse(sbi->s_sbh);
sb->s_fs_info = NULL;
/*
* Now that we are completely done shutting down the
On Oct 20, 2016, at 12:19 PM, Eric Sandeen <[email protected]> wrote:
>
> In ext4_put_super, we call brelse on the buffer head containing
> the ext4 superblock, but then try to use it when we stop the
> mmp thread, because when the thread shuts down it does:
>
> write_mmp_block
> ext4_mmp_csum_set
> ext4_has_metadata_csum
> WARN_ON_ONCE(ext4_has_feature_metadata_csum(sb)...)
>
> which reaches into sb->s_fs_info->s_es->s_feature_ro_compat,
> which lives in the superblock buffer s_sbh which we just released.
>
> Fix this by moving the brelse down to a point where we are no
> longer using it.
>
> Reported-by: Wang Shu <[email protected]>
> Signed-off-by: Eric Sandeen <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
> ---
>
> Note: found by inspection after a bug report via KASAN,
> compile-tested only.
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 6db81fb..f273212 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -862,7 +862,6 @@ static void ext4_put_super(struct super_block *sb)
> percpu_counter_destroy(&sbi->s_dirs_counter);
> percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
> percpu_free_rwsem(&sbi->s_journal_flag_rwsem);
> - brelse(sbi->s_sbh);
> #ifdef CONFIG_QUOTA
> for (i = 0; i < EXT4_MAXQUOTAS; i++)
> kfree(sbi->s_qf_names[i]);
> @@ -894,6 +893,9 @@ static void ext4_put_super(struct super_block *sb)
> }
> if (sbi->s_mmp_tsk)
> kthread_stop(sbi->s_mmp_tsk);
> +
> + /* Don't let this go until everything is done with the ext4 super */
> + brelse(sbi->s_sbh);
> sb->s_fs_info = NULL;
> /*
> * Now that we are completely done shutting down the
>
>
> --
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Cheers, Andreas
On Thu, Oct 20, 2016 at 02:26:38PM -0600, Andreas Dilger wrote:
> On Oct 20, 2016, at 12:19 PM, Eric Sandeen <[email protected]> wrote:
> >
> > In ext4_put_super, we call brelse on the buffer head containing
> > the ext4 superblock, but then try to use it when we stop the
> > mmp thread, because when the thread shuts down it does:
> >
> > write_mmp_block
> > ext4_mmp_csum_set
> > ext4_has_metadata_csum
> > WARN_ON_ONCE(ext4_has_feature_metadata_csum(sb)...)
> >
> > which reaches into sb->s_fs_info->s_es->s_feature_ro_compat,
> > which lives in the superblock buffer s_sbh which we just released.
> >
> > Fix this by moving the brelse down to a point where we are no
> > longer using it.
> >
> > Reported-by: Wang Shu <[email protected]>
> > Signed-off-by: Eric Sandeen <[email protected]>
>
> Reviewed-by: Andreas Dilger <[email protected]>
Applied, thanks.
- Ted