linux-kernel - Re: [PATCH v4 0/3] targeted TLB sync IPIs for lockless page table

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Message-ID: <64f3a75a-30ff-4bee-833c-be5dba05f72b@intel.com>
Date: Thu, 5 Feb 2026 07:09:15 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Lance Yang <lance.yang@...ux.dev>,
 "David Hildenbrand (Arm)" <david@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>
Cc: Liam.Howlett@...cle.com, akpm@...ux-foundation.org,
 aneesh.kumar@...nel.org, arnd@...db.de, baohua@...nel.org,
 baolin.wang@...ux.alibaba.com, boris.ostrovsky@...cle.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, dev.jain@....com, hpa@...or.com,
 hughd@...gle.com, ioworker0@...il.com, jannh@...gle.com, jgross@...e.com,
 kvm@...r.kernel.org, linux-arch@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 lorenzo.stoakes@...cle.com, mingo@...hat.com, npache@...hat.com,
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Subject: Re: [PATCH v4 0/3] targeted TLB sync IPIs for lockless page table

On 2/5/26 07:01, Lance Yang wrote:
> So for now, neither approach looks good: tracking on the read side adss
> cost to GUP-fast, and syncing on the write side e.g. synchronize_rcu()
> is too slow on large systems.

Which of the writers truly *need* synchronize_rcu()?

What are they doing with the memory that they can't move forward unless
it's quiescent *now*?