linux-kernel - Re: [PATCH 1/8] mm: Fix endless reclaim on machines with unaccepted memory

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Message-ID: <7564cf76-115b-4d5b-bfbd-fd3b1e55a5c1@redhat.com>
Date: Tue, 6 Aug 2024 14:00:07 +0200
From: David Hildenbrand <david@...hat.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "Borislav Petkov (AMD)" <bp@...en8.de>, Mel Gorman <mgorman@...e.de>,
 Vlastimil Babka <vbabka@...e.cz>
Cc: Tom Lendacky <thomas.lendacky@....com>, Mike Rapoport <rppt@...nel.org>,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Jianxiong Gao <jxgao@...gle.com>,
 stable@...r.kernel.org
Subject: Re: [PATCH 1/8] mm: Fix endless reclaim on machines with unaccepted
 memory

On 05.08.24 16:59, Kirill A. Shutemov 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.
> 
> Make unaccepted memory free from watermark check point of view. This way
> unaccepted memory will never be the trigger of memory reclaim.
> Accept more memory in the get_page_from_freelist() if needed.
> 
> 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+
> ---

Nothing jumped at me, sounds reasonable

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb