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Message-ID: <1583329007.7365.151.camel@lca.pw>
Subject: Re: [PATCH] cgroup: fix psi_show() crash on 32bit ino archs
From:   Qian Cai <cai@lca.pw>
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     tj@kernel.org, lizefan@huawei.com, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Wed, 04 Mar 2020 08:36:47 -0500
In-Reply-To: <20200224162906.GB1674@cmpxchg.org>
References: <20200224030007.3990-1-cai@lca.pw>
         <20200224162906.GB1674@cmpxchg.org>
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On Mon, 2020-02-24 at 11:29 -0500, Johannes Weiner wrote:
> On Sun, Feb 23, 2020 at 10:00:07PM -0500, Qian Cai wrote:
> > Similar to the commit d7495343228f ("cgroup: fix incorrect
> > WARN_ON_ONCE() in cgroup_setup_root()"), cgroup_id(root_cgrp) does not
> > equal to 1 on 32bit ino archs which triggers all sorts of issues with
> > psi_show() on s390x. For example,
> > 
> >  BUG: KASAN: slab-out-of-bounds in collect_percpu_times+0x2d0/
> >  Read of size 4 at addr 000000001e0ce000 by task read_all/3667
> >  collect_percpu_times+0x2d0/0x798
> >  psi_show+0x7c/0x2a8
> >  seq_read+0x2ac/0x830
> >  vfs_read+0x92/0x150
> >  ksys_read+0xe2/0x188
> >  system_call+0xd8/0x2b4
> > 
> > Fix it by using cgroup_ino().
> > 
> > Fixes: 743210386c03 ("cgroup: use cgrp->kn->id as the cgroup ID")
> > Signed-off-by: Qian Cai <cai@lca.pw>
> 
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Tejun, can you take a look at this when you had a chance?