From: David Hildenbrand <david@redhat.com>
To: Sergei Trofimovich <slyfox@gentoo.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, Vlastimil Babka <vbabka@suse.cz>,
Andrey Konovalov <andreyknvl@gmail.com>
Subject: Re: [PATCH] mm: page_alloc: ignore init_on_free=1 for page alloc
Date: Fri, 26 Mar 2021 14:48:50 +0100 [thread overview]
Message-ID: <4e23d404-5125-6c9c-4aa7-5eff0fa1ba33@redhat.com> (raw)
In-Reply-To: <20210326112650.307890-1-slyfox@gentoo.org>
On 26.03.21 12:26, Sergei Trofimovich wrote:
> init_on_free=1 does not guarantee that free pages contain only zero bytes.
>
> Some examples:
> 1. page_poison=on takes presedence over init_on_alloc=1 / ini_on_free=1
s/ini_on_free/init_on_free/
> 2. free_pages_prepare() always poisons pages:
>
> if (want_init_on_free())
> kernel_init_free_pages(page, 1 << order);
> kernel_poison_pages(page, 1 << order
In next/master, it's the other way around already.
commit 855a9c4018f3219db8be7e4b9a65ab22aebfde82
Author: Andrey Konovalov <andreyknvl@gmail.com>
Date: Thu Mar 18 17:01:40 2021 +1100
kasan, mm: integrate page_alloc init with HW_TAGS
>
> I observed use of poisoned pages as the crash on ia64 booted with
> init_on_free=1 init_on_alloc=1 (CONFIG_PAGE_POISONING=y config).
> There pmd page contained 0xaaaaaaaa poison pages and led to early crash.
>
> The change drops the assumption that init_on_free=1 guarantees free
> pages to contain zeros.
>
> Alternative would be to make interaction between runtime poisoning and
> sanitizing options and build-time debug flags like CONFIG_PAGE_POISONING
> more coherent. I took the simpler path.
>
I thought latest work be Vlastimil tried to tackle that. To me, it feels
like page_poison=on and init_on_free=1 should bail out and disable one
of both things. Having both at the same time doesn't sound helpful.
> Tested the fix on rx3600.
Fixes: ?
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-03-26 13:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 11:26 [PATCH] mm: page_alloc: ignore init_on_free=1 for page alloc Sergei Trofimovich
2021-03-26 13:48 ` David Hildenbrand [this message]
2021-03-26 15:00 ` Andrey Konovalov
2021-03-26 16:42 ` Sergei Trofimovich
2021-03-29 12:10 ` Vlastimil Babka
2021-03-29 22:00 ` Andrey Konovalov
2021-03-29 22:07 ` Vlastimil Babka
2021-03-30 14:48 ` Andrey Konovalov
2021-03-26 14:17 ` Vlastimil Babka
2021-03-26 17:25 ` Sergei Trofimovich
2021-03-27 18:03 ` Sergei Trofimovich
2021-03-27 18:21 ` [PATCH v2] mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1 Sergei Trofimovich
2021-03-29 9:23 ` David Hildenbrand
2021-03-29 11:59 ` Vlastimil Babka
2021-03-29 22:25 ` [PATCH v3] " Sergei Trofimovich
2021-03-30 8:39 ` David Hildenbrand
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