linux-kernel - Re: [syzbot] [crypto?] general protection fault in scatterwalk

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Message-ID: <CAKEwX=PYK3hUzgm+qfs2sNU686RaE+_M3W4Zo_Q4mTMAgKaB2A@mail.gmail.com>
Date: Wed, 27 Dec 2023 15:26:34 -0800
From: Nhat Pham <nphamcs@...il.com>
To: Barry Song <21cnbao@...il.com>
Cc: Chengming Zhou <zhouchengming@...edance.com>, Chris Li <chrisl@...nel.org>, 
	syzbot <syzbot+3eff5e51bf1db122a16e@...kaller.appspotmail.com>, 
	akpm@...ux-foundation.org, davem@...emloft.net, herbert@...dor.apana.org.au, 
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, yosryahmed@...gle.com
Subject: Re: [syzbot] [crypto?] general protection fault in
 scatterwalk_copychunks (5)

On Wed, Dec 27, 2023 at 3:10 AM Barry Song <21cnbao@...il.com> wrote:
>
> On Wed, Dec 27, 2023 at 5:16 PM Chengming Zhou
> <zhouchengming@...edance.com> wrote:
> >
> > Thanks for your explanation! Maybe it's best for us to return to 2 pages
> > if no other people's comments. And this really need more documentation :-)

Fine by me. Hmm we're basically wasting one extra page per CPU (since
these buffers are per-CPU), correct? That's not ideal, but not *too*
bad for now I suppose...

>
> I agree. we need some doc.
>
> besides, i actually think we can skip zswap frontend if
> over-compression is really
> happening.

IIUC, zsmalloc already checked that - and most people are (or should
be) using zsmalloc for zswap anyway. I wouldn't be opposed to adding
an added layer of protection on the zswap side, but not super high
priority I'd say.