Messages in this thread | | | Date | Mon, 13 Feb 2023 13:44:07 +0100 | Subject | Re: [PATCH v5 2/6] ksm: support unsharing zero pages placed by KSM | From | David Hildenbrand <> |
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On 04.02.23 07:18, yang.yang29@zte.com.cn wrote:
[sorry, was on vacation last week]
>> Why use flags if they both conditions are mutually exclusive? > > Just to make the return value of break_ksm_pmd_entry() more expressive and > understandable. because break_ksm_pmd_entry have three types of returned > values (0, 1, 2).
It adds confusion. Just simplify it please.
> >> MADV_UNMERGEABLE -> unmerge_ksm_pages() will never unshare the shared >> zeropage? I thought the patch description mentions that that is one of >> the goals? > > No, MADV_UNMERGEABLE will trigger KSM to unshare the shared zeropages in the > context of "get_next_rmap_item() -> unshare_zero_pages(), but not directly in the > context of " madvise()-> unmerge_ksm_pages() ". The reason for this is to avoid > increasing long delays of madvise() calling on unsharing zero pages. >
Why do we care and make this case special?
-- Thanks,
David / dhildenb
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