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From:   Joel Fernandes <joel@joelfernandes.org>
Date:   Wed, 30 Aug 2023 08:17:18 -0400
Message-ID: <CAEXW_YRvCQP+eoWmbnEwXs925xXQYPDuCp+iyzWeo8HY9dq+Ew@mail.gmail.com>
Subject: Re: [PATCH 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug
To:     Matthew Wilcox <willy@infradead.org>
Cc:     linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Uladzislau Rezki <urezki@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Zhen Lei <thunder.leizhen@huaweicloud.com>,
        "Paul E . McKenney" <paulmck@kernel.org>, rcu@vger.kernel.org,
        Zqiang <qiang.zhang1211@gmail.com>, linux-mm@kvack.org
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On Wed, Aug 30, 2023 at 8:08=E2=80=AFAM Matthew Wilcox <willy@infradead.org=
> wrote:
>
> On Wed, Aug 30, 2023 at 11:03:59AM +0000, Joel Fernandes (Google) wrote:
> > It is unsafe to dump vmalloc area information when trying to do so from
> > some contexts. Add a safer trylock version of the same function to do a
> > best-effort VMA finding and use it from vmalloc_dump_obj().
> >
> > Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com>
> > Cc: Paul E. McKenney <paulmck@kernel.org>
> > Cc: rcu@vger.kernel.org
> > Cc: Zqiang <qiang.zhang1211@gmail.com>
> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
>
> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Thanks!

> I once started writing something similar, but got distracted and the
> immediate problem got solved a different way.
>
> It does make me wonder if we couldn't make this tree RCU-safe, but
> that's obviously a much larger job.

Yes, that would be nice.

 - Joel