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Date: Fri, 8 May 2026 18:07:40 +0000
From: Dmitry Ilvokhin <d@ilvokhin.com>
To: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, hawk@kernel.org,
	Matthew Wilcox <willy@infradead.org>, linux-mm@kvack.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>, Zi Yan <ziy@nvidia.com>,
	David Hildenbrand <david@kernel.org>,
	Lorenzo Stoakes <ljs@kernel.org>, Shuah Khan <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	kernel-team@cloudflare.com
Subject: Re: [PATCH 1/2] mm/page_alloc: add tracepoints for zone->lock
 acquisitions
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References: <20260508162207.3315781-1-hawk@kernel.org>
 <20260508102948.b1c687e623fabec65580f258@linux-foundation.org>
 <832e4333-4079-4865-8ad8-3dd8868fb964@kernel.org>
 <4f61457e-deff-430f-8a1e-d3c33c925db3@kernel.org>
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In-Reply-To: <4f61457e-deff-430f-8a1e-d3c33c925db3@kernel.org>

On Fri, May 08, 2026 at 07:40:51PM +0200, Vlastimil Babka (SUSE) wrote:
> On 5/8/26 7:38 PM, Vlastimil Babka (SUSE) wrote:
> > On 5/8/26 7:29 PM, Andrew Morton wrote:
> >> e .configOn Fri,  8 May 2026 18:22:06 +0200 hawk@kernel.org wrote:
> >>
> >>> Add tracepoints to the page allocator fast paths that acquire
> >>> zone->lock, allowing diagnosis of lock contention in production.
> >>
> >> Thanks, I'm surprised we haven't done this yet.
> > 
> > There was a recent attempt [1]. Not being a generic solution wasn't welcome.
> > 
> > [1] https://lore.kernel.org/all/cover.1772206930.git.d@ilvokhin.com/
> 
> And this is the generic solution I think?
> 
> https://lore.kernel.org/all/cover.1777999826.git.d@ilvokhin.com/

Thanks for cc'ing me, Vlastimil.

Yes, this is an attempt at a generic solution for tracing contended
locks, including spinlocks, so it should also cover the use case
proposed in this patchset.

In fact, zone->lock contention was one of the primary motivations for
this work.