linux-kernel - Re: [PATCH 1/2] mm: thp: relax __GFP_THISNODE for MADV

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Date:   Mon, 29 Oct 2018 10:00:35 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Balbir Singh <bsingharora@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
        David Rientjes <rientjes@...gle.com>,
        Andrea Argangeli <andrea@...nel.org>,
        Zi Yan <zi.yan@...rutgers.edu>,
        Stefan Priebe - Profihost AG <s.priebe@...fihost.ag>,
        "Kirill A. Shutemov" <kirill@...temov.name>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Stable tree <stable@...r.kernel.org>
Subject: Re: [PATCH 1/2] mm: thp:  relax __GFP_THISNODE for MADV_HUGEPAGE
 mappings

On Mon 29-10-18 16:17:52, Balbir Singh wrote:
[...]
> I wonder if alloc_pool_huge_page() should also trim out it's logic
> of __GFP_THISNODE for the same reasons as mentioned here. I like
> that we round robin to alloc the pool pages, but __GFP_THISNODE
> might be an overkill for that case as well.

alloc_pool_huge_page uses __GFP_THISNODE for a different reason than
THP. We really do want to allocated for a per-node pool. THP can
fallback or use a different node.

These hugetlb allocations might be disruptive and that is an expected
behavior because this is an explicit requirement from an admin to
pre-allocate large pages for the future use. __GFP_RETRY_MAYFAIL just
underlines that requirement.

Maybe the compaction logic could be improved and that might be a shared
goal with future changes though.
-- 
Michal Hocko
SUSE Labs