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From: Chris Li <chrisl@kernel.org>
Date: Thu, 25 Jan 2024 17:09:43 -0800
Message-ID: <CAF8kJuN25avTEgNTXdoz7N9eRuNTCdtGLA_kCuKB=_TRYT48cA@mail.gmail.com>
Subject: Re: [PATCH 2/2] mm: zswap: remove unnecessary tree cleanups in zswap_swapoff()
To: Yosry Ahmed <yosryahmed@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>, Andrew Morton <akpm@linux-foundation.org>, 
	Nhat Pham <nphamcs@gmail.com>, Chengming Zhou <zhouchengming@bytedance.com>, 
	Huang Ying <ying.huang@intel.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org
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Hi Yosry,

On Thu, Jan 25, 2024 at 2:34=E2=80=AFPM Yosry Ahmed <yosryahmed@google.com>=
 wrote:
>
> > > problem is that after the entry is isolated from the zswap LRU, we
> > > need to grab the tree lock to make sure it's still there and get a
> > > ref, and just trying to lock the tree may be a UAF if we race with
> > > swapoff.
> >
> > I feel it is very wrong to have the tree freed while having
> > outstanding entry allocationed from the tree pending.
> > I would want to avoid that situation if possible.
>
> This should be the case with Chengming's solution.

Thanks for confirming. Looking forward to Chenming's patch.

Chris