Messages in this thread | | | From | David Hildenbrand <> | Subject | Re: [PATCH] mm: page_alloc: ignore init_on_free=1 for page alloc | Date | Fri, 26 Mar 2021 14:48:50 +0100 |
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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
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