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Date: Wed, 14 Oct 2026 15:03:01 +0200
From: Christoph Hellwig <hch@lst.de>
To: Vitaly Wool <vitaly.wool@konsulko.se>
Cc: Harry Yoo <harry@kernel.org>, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Roman Gushchin <roman.gushchin@linux.dev>,
	David Rientjes <rientjes@google.com>,
	Christoph Lameter <cl@gentwo.org>, Hao Li <hao.li@linux.dev>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@kernel.org>,
	Damien Le Moal <dlemoal@kernel.org>, Christoph Hellwig <hch@lst.de>,
	vitaly.vul@partner.samsung.com
Subject: Re: [PATCH] mempool: optimize mempool resizing
Message-ID: <20261014130301.GC15407@lst.de>
References: <20261013091408.1231786-1-vitaly.wool@konsulko.se> <20261014084528.1280968-1-vitaly.wool@konsulko.se>
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On Wed, Oct 14, 2026 at 10:45:28AM +0200, Vitaly Wool wrote:
> We are using mempool to store a large set of preallocated rather big buffers. In case
> of memory pressure we'd call mempool_resize() (via shrinker callbacks) to reduce the
> amount of memory occupied by that set, and when the situation stabilizes, we'd go back
> to the original set again.
> 
> Imagine you have a mempool with 10000 elements, and you have to reduce it to 3000. Then
> if you at some point want to go back to 10000, you'll end up reallocating the elements

Who is "we" and where is the code?  This is a highly unusual, not to
say most like broken usage of mempools.  If you need changes to support
such a use case you should include a link to the intree user (or bundle
it with the submission of the new code).