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Message-ID: <ZldCwWqI0JVIqh_3@J2N7QTR9R3.cambridge.arm.com>
Date: Wed, 29 May 2024 15:59:13 +0100
From: Mark Rutland <mark.rutland@....com>
To: Barry Song <21cnbao@...il.com>
Cc: Will Deacon <will@...nel.org>, akpm@...ux-foundation.org,
linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, Barry Song <v-songbaohua@...o.com>,
Lance Yang <ioworker0@...il.com>,
Ryan Roberts <ryan.roberts@....com>,
David Hildenbrand <david@...hat.com>,
Jeff Xie <xiehuan09@...il.com>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Michal Hocko <mhocko@...e.com>, Minchan Kim <minchan@...nel.org>,
Muchun Song <songmuchun@...edance.com>,
Peter Xu <peterx@...hat.com>, Yang Shi <shy828301@...il.com>,
Yin Fengwei <fengwei.yin@...el.com>,
Zach O'Keefe <zokeefe@...gle.com>,
Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH] mm: arm64: Fix the out-of-bounds issue in
contpte_clear_young_dirty_ptes
On Tue, May 28, 2024 at 08:39:55PM +1200, Barry Song wrote:
> On Tue, May 28, 2024 at 8:26 PM Mark Rutland <mark.rutland@....com> wrote:
> > On Fri, May 24, 2024 at 12:54:44PM +1200, Barry Song wrote:
> > > From: Barry Song <v-songbaohua@...o.com>
> > >
> > > We are passing a huge nr to __clear_young_dirty_ptes() right
> > > now. While we should pass the number of pages, we are actually
> > > passing CONT_PTE_SIZE. This is causing lots of crashes of
> > > MADV_FREE, panic oops could vary everytime.
> > >
> > > Fixes: 89e86854fb0a ("mm/arm64: override clear_young_dirty_ptes() batch helper")
> >
> > I was seeing ths same thing on v6.10-rc1 (syzkaller splat and reproducer
> > included at the end of the mail). The patch makes sense to me, and fixed the
> > splat in testing, so:
> >
> > Reviewed-by: Mark Rutland <mark.rutland@....com>
> > Tested-by: Mark Rutland <mark.rutland@....com>
>
> Thanks!
>
> > Since this only affects arm64 and is already in mainline, I assume the fix
> > should go via the arm64 tree even though the broken commit went via mm.
>
> Either mm or arm64 is fine with me, but I noticed that Andrew has already
> included it in mm-hotfixes-unstable. If it works, we may want to stick with
> that. :-)
Going via mm is also fine by me, I had just expected it'd be quicker to
go via arm64 (and evidently I was wrong there!). :)
Mark.
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