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From:   Zhaoyang Huang <huangzhaoyang@gmail.com>
Date:   Mon, 20 Jun 2022 19:23:34 +0800
Message-ID: <CAGWkznE5cFfdtmQ2j57goWtpfPGYPsd5Oi3pvb9vcfifodR9OQ@mail.gmail.com>
Subject: Re: [PATCH] mm: fix racing of vb->va when kasan enabled
To:     Uladzislau Rezki <urezki@gmail.com>
Cc:     "zhaoyang.huang" <zhaoyang.huang@unisoc.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Ke Wang <ke.wang@unisoc.com>, Christoph Hellwig <hch@lst.de>
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On Mon, Jun 20, 2022 at 6:44 PM Uladzislau Rezki <urezki@gmail.com> wrote:
>
> > > >
> > > Is it easy to reproduce? If so could you please describe the steps? As i see
> > > the freeing of the "vb" is RCU safe whereas vb->va is not. But from the first
> > > glance i do not see how it can accessed twice. Hm..
> > It was raised from a monkey test on A13_k515 system and got 1/20 pcs
> > failed. IMO, vb->va which out of vmap_purge_lock protection could race
> > with a concurrent ra freeing within __purge_vmap_area_lazy.
> >
> Do you have exact steps how you run "monkey" test?
There are about 30+ kos inserted during startup which could be a
specific criteria for reproduction. Do you have doubts about the test
result or the solution?
>
> --
> Uladzislau Rezki