linux-kernel - Re: [PATCH] mm: Fix endless reclaim on machines with unaccepted memory.

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Message-ID: <CAMGD6P1E+hoH_HGhmBvXskMgNvALYiNj-dhJWvzQuTx4sd1SxQ@mail.gmail.com>
Date: Wed, 17 Jul 2024 14:00:56 -0700
From: Jianxiong Gao <jxgao@...gle.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, "Borislav Petkov (AMD)" <bp@...en8.de>, 
	Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>, Tom Lendacky <thomas.lendacky@....com>, 
	Mike Rapoport <rppt@...nel.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	stable@...r.kernel.org
Subject: Re: [PATCH] mm: Fix endless reclaim on machines with unaccepted memory.

On Tue, Jul 16, 2024 at 6:00 AM Kirill A. Shutemov
<kirill.shutemov@...ux.intel.com> wrote:
>
> Unaccepted memory is considered unusable free memory, which is not
> counted as free on the zone watermark check. This causes
> get_page_from_freelist() to accept more memory to hit the high
> watermark, but it creates problems in the reclaim path.
>
> The reclaim path encounters a failed zone watermark check and attempts
> to reclaim memory. This is usually successful, but if there is little or
> no reclaimable memory, it can result in endless reclaim with little to
> no progress. This can occur early in the boot process, just after start
> of the init process when the only reclaimable memory is the page cache
> of the init executable and its libraries.
>
> To address this issue, teach shrink_node() and shrink_zones() to accept
> memory before attempting to reclaim.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Reported-by: Jianxiong Gao <jxgao@...gle.com>
> Fixes: dcdfdd40fa82 ("mm: Add support for unaccepted memory")
> Cc: stable@...r.kernel.org # v6.5+

Tested-by: Jianxiong Gao <jxgao@...gle.com>
I have verified that the patch fixes the systemd issue reported.