linux-kernel - Re: [PATCH v8 00/23] SLUB percpu sheaves

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Message-ID: <c0eb4acf-47ff-4e39-8d32-4e5f3857a851@suse.cz>
Date: Wed, 15 Oct 2025 10:32:44 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Christoph Hellwig <hch@...radead.org>
Cc: Suren Baghdasaryan <surenb@...gle.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>,
 Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>,
 Roman Gushchin <roman.gushchin@...ux.dev>, Harry Yoo <harry.yoo@...cle.com>,
 Uladzislau Rezki <urezki@...il.com>,
 Sidhartha Kumar <sidhartha.kumar@...cle.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
 maple-tree@...ts.infradead.org, Alexei Starovoitov <ast@...nel.org>,
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 Venkat Rao Bagalkote <venkat88@...ux.ibm.com>,
 Qianfeng Rong <rongqianfeng@...o.com>, Wei Yang <richard.weiyang@...il.com>,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 WangYuli <wangyuli@...ontech.com>, Jann Horn <jannh@...gle.com>,
 Pedro Falcato <pfalcato@...e.de>
Subject: Re: [PATCH v8 00/23] SLUB percpu sheaves

On 10/8/25 08:04, Christoph Hellwig wrote:
> On Tue, Oct 07, 2025 at 10:03:04AM +0200, Vlastimil Babka wrote:
>> Basically it's for situations where you have an upper bound on the objects
>> you might need to allocate in some restricted context where you can't fail
>> but also can't reclaim etc. The steps are:
> 
> Ok, so you still need a step where you reserve, which can fail and
> only after that guarantee you can allocate up to the reservation?  I.e.
> not a replacement for mempools?  Just asking because I recently had

Yeah, not a replacement for mempools which have their special semantics.

> to implement a mempool_alloc_batch to allow grabbing multiple objects
> out of a mempool safely for something I'm working on.

I can imagine allocating multiple objects can be difficult to achieve with
the mempool's guaranteed progress semantics. Maybe the mempool could serve
prefilled sheaves?