linux-kernel - Re: [PATCH] mm: split thp synchronously on MADV

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Date:   Tue, 23 Nov 2021 18:20:02 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>, Zi Yan <ziy@...dia.com>,
        Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: split thp synchronously on MADV_DONTNEED

On 23.11.21 18:17, Shakeel Butt wrote:
> On Tue, Nov 23, 2021 at 8:57 AM David Hildenbrand <david@...hat.com> wrote:
>>
> [...]
>>>>
>>>> I do wonder which these locking contexts are exactly, and if we could
>>>> also do the same thing on ordinary munmap -- because I assume it can be
>>>> similarly problematic for some applications.
>>>
>>> This is a good question regarding munmap. One main difference is
>>> munmap takes mmap_lock in write mode and usually performance critical
>>> applications avoid such operations.
>>
>> Maybe we can extend it too most page zapping, if that makes things simpler.
>>
> 
> Do you mean doing sync THP split for most of page zapping functions
> (but only if that makes things simpler)?
> 

Yes -- if there are no downsides.

-- 
Thanks,

David / dhildenb