linux-kernel - Re: [PATCH] hugetlb: increase hugepage reservations when using node-specific "hugepages=" cmdline

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Message-Id: <20260123031400.37480-1-lizhe.67@bytedance.com>
Date: Fri, 23 Jan 2026 11:14:00 +0800
From: "Li Zhe" <lizhe.67@...edance.com>
To: <akpm@...ux-foundation.org>
Cc: <david@...nel.org>, <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>, 
	<lizhe.67@...edance.com>, <muchun.song@...ux.dev>, <osalvador@...e.de>
Subject: Re: [PATCH] hugetlb: increase hugepage reservations when using node-specific "hugepages=" cmdline

On Thu, 22 Jan 2026 14:19:00 -0800, akpm@...ux-foundation.org wrote:

> On Thu, 22 Jan 2026 11:50:02 +0800 "Li Zhe" <lizhe.67@...edance.com> wrote:
> 
> > Commit 3dfd02c90037 ("hugetlb: increase number of reserving hugepages
> > via cmdline") raised the number of hugepages that can be reserved
> > through the boot-time "hugepages=" parameter for the non-node-specific
> > case, but left the node-specific form of the same parameter unchanged.
> > 
> > This patch extends the same optimization to node-specific reservations.
> > When HugeTLB vmemmap optimization (HVO) is enabled and a node cannot
> > satisfy the requested hugepages, the code first releases ordinary
> > struct-page memory of hugepages obtained from the buddy allocator,
> > allowing their struct-page memory to be reclaimed and reused for
> > additional hugepage reservations on that node.
> > 
> > This is particularly beneficial for configurations that require
> > identical, large per-node hugepage reservations. On a four-node, 384 GB
> > x86 VM, the patch raises the attainable 2 MiB hugepage reservation from
> > under 374 GB to more than 379 GB.
> > 
> 
> Thanks.
> 
> I *think* the hugepages= documentation in
> Documentation/admin-guide/mm/hugetlbpage.rst is still up to date and
> complete, but can you please check it, see if there's somethig we should
> do?

After carefully re-reading the documentation on the "hugepages="
parameter, I did not see any points that could or should be optimized
regarding the number of reserved huge pages.

Thanks,
Zhe