linux-kernel - Re: [PATCH RESEND v3 1/2] mm/tlb: skip redundant IPI when TLB flush already synchronized

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Message-ID: <4d94363b-5b3b-4401-a9d8-da136d71f8c3@kernel.org>
Date: Fri, 9 Jan 2026 15:13:04 +0100
From: "David Hildenbrand (Red Hat)" <david@...nel.org>
To: Lance Yang <lance.yang@...ux.dev>
Cc: dave.hansen@...el.com, dave.hansen@...ux.intel.com, will@...nel.org,
 aneesh.kumar@...nel.org, npiggin@...il.com, peterz@...radead.org,
 tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
 hpa@...or.com, arnd@...db.de, akpm@...ux-foundation.org,
 lorenzo.stoakes@...cle.com, ziy@...dia.com, baolin.wang@...ux.alibaba.com,
 Liam.Howlett@...cle.com, npache@...hat.com, ryan.roberts@....com,
 dev.jain@....com, baohua@...nel.org, shy828301@...il.com, riel@...riel.com,
 jannh@...gle.com, linux-arch@...r.kernel.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, ioworker0@...il.com
Subject: Re: [PATCH RESEND v3 1/2] mm/tlb: skip redundant IPI when TLB flush
 already synchronized


>> What could work is tracking "tlb_table_flush_sent_ipi" really when we
>> are flushing the TLB for removed/unshared tables, and maybe resetting
>> it ... I don't know when from the top of my head.
> 
> Not sure what's the best way forward here :(
> 
>>
>> v2 was simpler IMHO.
> 
> The main concern Dave raised was that with PV hypercalls or when
> INVLPGB is available, we can't tell from a static check whether IPIs
> were actually sent.

Why can't we set the boolean at runtime when initializing the pv_ops 
structure, when we are sure that it is allowed?

-- 
Cheers

David