Messages in this thread | | | Subject | Re: [PATCH v2 5/5] mm, page_poison: remove CONFIG_PAGE_POISONING_ZERO | From | David Hildenbrand <> | Date | Wed, 11 Nov 2020 16:45:53 +0100 |
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On 03.11.20 16:22, Vlastimil Babka wrote: > CONFIG_PAGE_POISONING_ZERO uses the zero pattern instead of 0xAA. It was > introduced by commit 1414c7f4f7d7 ("mm/page_poisoning.c: allow for zero > poisoning"), noting that using zeroes retains the benefit of sanitizing content > of freed pages, with the benefit of not having to zero them again on alloc, and > the downside of making some forms of corruption (stray writes of NULLs) harder > to detect than with the 0xAA pattern. Together with > CONFIG_PAGE_POISONING_NO_SANITY it made possible to sanitize the contents on > free without checking it back on alloc. > > These days we have the init_on_free() option to achieve sanitization with > zeroes and to save clearing on alloc (and without checking on alloc). Arguably > if someone does choose to check the poison for corruption on alloc, the savings > of not clearing the page are secondary, and it makes sense to always use the > 0xAA poison pattern. Thus, remove the CONFIG_PAGE_POISONING_ZERO option for > being redundant.
I agree, this simplifies things ... and I don't see a need to complicate things to speed up corner-case debug mechanisms. Thanks!
Acked-by: David Hildenbrand <david@redhat.com>
-- Thanks,
David / dhildenb
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