From: Andrew Morton <akpm@linux-foundation.org>
To: Li Xinhai <lixinhai.lxh@gmail.com>
Cc: linux-mm@kvack.org, Mike Kravetz <mike.kravetz@oracle.com>,
Peter Xu <peterx@redhat.com>
Subject: Re: [PATCH] mm/hugetlb.c: fix unnecessary address expansion of pmd sharing
Date: Tue, 29 Dec 2020 11:21:40 -0800 [thread overview]
Message-ID: <20201229112140.7f698899cb7f8b04873c79fa@linux-foundation.org> (raw)
In-Reply-To: <20201229042125.2663029-1-lixinhai.lxh@gmail.com>
On Tue, 29 Dec 2020 12:21:25 +0800 Li Xinhai <lixinhai.lxh@gmail.com> wrote:
> The current code would unnecessarily expand the address range. Consider
> one example, (start, end) = (1G-2M, 3G+2M), and (vm_start, vm_end) =
> (1G-4M, 3G+4M), the expected adjustment should be keep (1G-2M, 3G+2M)
> without expand. But the current result will be (1G-4M, 3G+4M). Actually,
> the range (1G-4M, 1G) and (3G, 3G+4M) would never been involved in pmd
> sharing.
>
> After this patch, if pud aligned *start across vm_start, then we know the
> *start and vm_start are in same pud_index, and vm_start is not pud
> aligned, so don't adjust *start. Same logic applied to *end.
Thanks. What are the user-visible runtime effects of this issue?
next prev parent reply other threads:[~2020-12-29 19:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 4:21 Li Xinhai
2020-12-29 19:21 ` Andrew Morton [this message]
2020-12-29 21:20 ` Mike Kravetz
2020-12-31 17:56 ` Mike Kravetz
2021-01-02 11:56 ` Li Xinhai
2021-01-04 3:55 ` Mike Kravetz
2021-01-04 7:10 ` Li Xinhai
2021-01-04 18:59 ` Mike Kravetz
2021-01-05 2:10 ` Li Xinhai
2021-01-05 2:38 ` Li Xinhai
2021-01-05 18:20 ` Mike Kravetz
2020-12-30 18:42 ` Peter Xu
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