linux-ext4 - Re: Report 1 in ext4 and journal based on v5.17-rc1

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 23 Feb 2022 12:30:12 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     Jan Kara <jack@...e.cz>
Cc:     torvalds@...ux-foundation.org, damien.lemoal@...nsource.wdc.com,
        linux-ide@...r.kernel.org, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        will@...nel.org, tglx@...utronix.de, rostedt@...dmis.org,
        joel@...lfernandes.org, sashal@...nel.org, daniel.vetter@...ll.ch,
        chris@...is-wilson.co.uk, duyuyang@...il.com,
        johannes.berg@...el.com, tj@...nel.org, tytso@....edu,
        willy@...radead.org, david@...morbit.com, amir73il@...il.com,
        bfields@...ldses.org, gregkh@...uxfoundation.org,
        kernel-team@....com, linux-mm@...ck.org, akpm@...ux-foundation.org,
        mhocko@...nel.org, minchan@...nel.org, hannes@...xchg.org,
        vdavydov.dev@...il.com, sj@...nel.org, jglisse@...hat.com,
        dennis@...nel.org, cl@...ux.com, penberg@...nel.org,
        rientjes@...gle.com, vbabka@...e.cz, ngupta@...are.org,
        linux-block@...r.kernel.org, axboe@...nel.dk,
        paolo.valente@...aro.org, josef@...icpanda.com,
        linux-fsdevel@...r.kernel.org, viro@...iv.linux.org.uk,
        jack@...e.com, jlayton@...nel.org, dan.j.williams@...el.com,
        hch@...radead.org, djwong@...nel.org,
        dri-devel@...ts.freedesktop.org, airlied@...ux.ie,
        rodrigosiqueiramelo@...il.com, melissa.srw@...il.com,
        hamohammed.sa@...il.com
Subject: Re: Report 1 in ext4 and journal based on v5.17-rc1

On Tue, Feb 22, 2022 at 09:27:23AM +0100, Jan Kara wrote:
> On Thu 17-02-22 20:10:03, Byungchul Park wrote:
> > [    7.009608] ===================================================
> > [    7.009613] DEPT: Circular dependency has been detected.
> > [    7.009614] 5.17.0-rc1-00014-g8a599299c0cb-dirty #30 Tainted: G        W
> > [    7.009616] ---------------------------------------------------
> > [    7.009617] summary
> > [    7.009618] ---------------------------------------------------
> > [    7.009618] *** DEADLOCK ***
> > [    7.009618]
> > [    7.009619] context A
> > [    7.009619]     [S] (unknown)(&(bit_wait_table + i)->dmap:0)
> > [    7.009621]     [W] down_write(&ei->i_data_sem:0)
> > [    7.009623]     [E] event(&(bit_wait_table + i)->dmap:0)
> > [    7.009624]
> > [    7.009625] context B
> > [    7.009625]     [S] down_read(&ei->i_data_sem:0)
> > [    7.009626]     [W] wait(&(bit_wait_table + i)->dmap:0)
> > [    7.009627]     [E] up_read(&ei->i_data_sem:0)
> > [    7.009628]
> 
> Looking into this I have noticed that Dept here tracks bitlocks (buffer
> locks in particular) but it apparently treats locks on all buffers as one
> locking class so it conflates lock on superblock buffer with a lock on
> extent tree block buffer. These are wastly different locks with different
> locking constraints. So to avoid false positives in filesystems we will
> need to add annotations to differentiate locks on different buffers (based
> on what the block is used for). Similarly how we e.g. annotate i_rwsem for
> different inodes.

Hi Jan Kara,

I just understood why some guys in this space got mad at Dept reports.
I barely got reports from the lock you mentioned with my system -
precisely speaking only one, even though I've been rebooting my system
many times. But another report that someone gave for me showed there
were a lot of reports from the lock.

Your comment and the report are so much helpful. I need to assign
each's own class first for the buffer locks. Thank you very much.

Thanks,
Byungchul

> 
> 								Honza
> -- 
> Jan Kara <jack@...e.com>
> SUSE Labs, CR