From: Andrew Morton <akpm@linux-foundation.org>
To: Marco Elver <elver@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
yee.lee@mediatek.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
"open list:KFENCE" <kasan-dev@googlegroups.com>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-arm-kernel@lists.infradead.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH v2 1/1] mm: kfence: apply kmemleak_ignore_phys on early allocated pool
Date: Tue, 19 Jul 2022 16:13:56 -0700 [thread overview]
Message-ID: <20220719161356.df8d7f6fc5414cc9cc7f8302@linux-foundation.org> (raw)
In-Reply-To: <CANpmjNPhhPUZFSZaLbwyJfACWMOqFchvm-Sx+iwGSM3sxkky8Q@mail.gmail.com>
On Mon, 18 Jul 2022 16:26:25 +0200 Marco Elver <elver@google.com> wrote:
> On Sat, 16 Jul 2022 at 20:43, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> [...]
> > > - This patch has been accused of crashing the kernel:
> > >
> > > https://lkml.kernel.org/r/YsFeUHkrFTQ7T51Q@xsang-OptiPlex-9020
> > >
> > > Do we think that report is bogus?
> >
> > I think all of this is highly architecture-specific...
>
> The report can be reproduced on i386 with CONFIG_X86_PAE=y. But e.g.
> mm/memblock.c:memblock_free() is also guilty of using __pa() on
> previously memblock_alloc()'d addresses. Looking at the phys addr
> before memblock_alloc() does virt_to_phys(), the result of __pa()
> looks correct even on PAE, at least for the purpose of passing it on
> to kmemleak(). So I don't know what that BUG_ON(slow_virt_to_phys() !=
> phys_addr) is supposed to tell us here.
>
It's only been nine years, so I'm sure Dave can remember why he added
it ;)
BUG_ON(slow_virt_to_phys((void *)x) != phys_addr);
in arch/x86/mm/physaddr.c:__phys_addr().
This kfence patch does seem to be desirable, but we can't proceed if
it's resulting in kernel crashes.
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next prev parent reply other threads:[~2022-07-19 23:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-28 11:37 [PATCH v2 0/1] mm: kfence: fix unexpected leak scan on kfence pool yee.lee
2022-06-28 11:37 ` [PATCH v2 1/1] mm: kfence: apply kmemleak_ignore_phys on early allocated pool yee.lee
2022-06-28 12:10 ` Marco Elver
2022-06-29 21:39 ` Catalin Marinas
2022-07-15 8:17 ` Geert Uytterhoeven
2022-07-15 23:33 ` Andrew Morton
2022-07-16 18:43 ` Geert Uytterhoeven
2022-07-18 14:26 ` Marco Elver
2022-07-19 23:13 ` Andrew Morton [this message]
2022-07-19 23:22 ` Dave Hansen
2022-08-01 14:05 ` Marco Elver
2022-07-19 11:50 ` Catalin Marinas
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