Linux-man Archive on
 help / color / Atom feed
From: "HORIGUCHI NAOYA(堀口 直也)" <>
To: Li Xinhai <>
Cc: "" <>,
	"" <>,
	Michal Hocko <>,
	Mike Kravetz <>,
	Naoya Horiguchi <>,
	linux-man <>
Subject: Re: [PATCH v2] mm/mempolicy: support MPOL_MF_STRICT for huge page mapping
Date: Fri, 14 Feb 2020 03:36:32 +0000
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, Feb 13, 2020 at 02:07:07AM +0000, Li Xinhai wrote:
> MPOL_MF_STRICT is used in mbind() for purposes:
> (1) MPOL_MF_STRICT is set alone without MPOL_MF_MOVE or MPOL_MF_MOVE_ALL,
>     to check if there is misplaced page and return -EIO;
> (2) MPOL_MF_STRICT is set with MPOL_MF_MOVE or MPOL_MF_MOVE_ALL, to check
>     if there is misplaced page which is failed to isolate, or page is
>     success on isolate but failed to move, and return -EIO.
> For non hugepage mapping, (1) and (2) are implemented as expectation.
> For hugepage mapping, (1) is not implemented. And in (2), the part about
> failed to isolate and report -EIO is not implemented.
> This patch implements the missed parts for hugepage mapping. Benefits
> with it applied:
> - User space can apply same code logic to handle mbind() on hugepage and
>   non hugepage mapping;
> - Reliably using MPOL_MF_STRICT alone to check whether there is misplaced
>   page or not when bind policy on address range, especially for address
>   range which contains both hugepage and non hugepage mapping.
> Analysis of potential impact to existing users:
> - If MPOL_MF_STRICT alone was previously used, hugetlb pages not following
>   the memory policy would not cause an EIO error.  After this change,
>   hugetlb pages are treated like all other pages. If  MPOL_MF_STRICT alone
>   is used and hugetlb pages do not follow memory policy an EIO error will
>   be returned.
> - For users who using MPOL_MF_STRICT with MPOL_MF_MOVE or
>   MPOL_MF_MOVE_ALL, the semantic about some pages could not be moved will
>   not be changed by this patch, because failed to isolate and failed to
>   move have same effects to users, so their existing code will not be
>   impacted.
> In mbind man page, the note about 'MPOL_MF_STRICT is ignored on huge page
> mappings' can be removed after this patch is applied.
> Signed-off-by: Li Xinhai <>
> Cc: Michal Hocko <>
> Cc: Mike Kravetz <>
> Cc: Naoya Horiguchi <>
> Cc: linux-man <>


Reviewed-by: Naoya Horiguchi <>

      parent reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13  2:07 Li Xinhai
2020-02-13 16:17 ` Mike Kravetz
2020-02-14  3:36 ` HORIGUCHI NAOYA(堀口 直也) [this message]

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-man Archive on

Archives are clonable:
	git clone --mirror linux-man/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-man linux-man/ \
	public-inbox-index linux-man

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone