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Date: Fri, 27 Feb 2026 12:39:00 +0000
From: Dmitry Ilvokhin <d@ilvokhin.com>
To: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	David Hildenbrand <david@kernel.org>,
	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
	"Liam R. Howlett" <Liam.Howlett@oracle.com>,
	Vlastimil Babka <vbabka@suse.cz>, Mike Rapoport <rppt@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Brendan Jackman <jackmanb@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>, Zi Yan <ziy@nvidia.com>,
	Oscar Salvador <osalvador@suse.de>,
	Qi Zheng <zhengqi.arch@bytedance.com>, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org,
	linux-cxl@vger.kernel.org, kernel-team@meta.com,
	Benjamin Cheatham <benjamin.cheatham@amd.com>
Subject: Re: [PATCH v3 5/5] mm: add tracepoints for zone lock
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In-Reply-To: <aaC7S2ensAGTyujc@linux.dev>

On Thu, Feb 26, 2026 at 01:31:48PM -0800, Shakeel Butt wrote:
> On Thu, Feb 26, 2026 at 01:25:01PM -0800, Andrew Morton wrote:
> > On Thu, 26 Feb 2026 11:14:52 -0800 Shakeel Butt <shakeel.butt@linux.dev> wrote:
> > 
> > > On Thu, Feb 26, 2026 at 06:26:22PM +0000, Dmitry Ilvokhin wrote:
> > > > Add tracepoint instrumentation to zone lock acquire/release operations
> > > > via the previously introduced wrappers.
> > > > 
> > > > The implementation follows the mmap_lock tracepoint pattern: a
> > > > lightweight inline helper checks whether the tracepoint is enabled and
> > > > calls into an out-of-line helper when tracing is active. When
> > > > CONFIG_TRACING is disabled, helpers compile to empty inline stubs.
> > > > 
> > > > The fast path is unaffected when tracing is disabled.
> > > > 
> > > > Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
> > > 
> > > ...
> > >
> > > > +void __zone_lock_do_trace_start_locking(struct zone *zone)
> > > > +{
> > > > +	trace_zone_lock_start_locking(zone);
> > > > +}
> > > > +EXPORT_SYMBOL(__zone_lock_do_trace_start_locking);
> > > 
> > > No reason to not have these as EXPORT_SYMBOL_GPL (& below)
> > 
> > Do we need the exports at all?
> 
> Very good point and we don't. I think this might just be copying the mmap_lock
> tracepoint wrappers which might need the exports as some drivers might be taking
> the mmap_lock.
> 
> Dmitry, please confirm (test) and let us know.

This is a good catch, thank you. I don't think we need EXPORT_SYMBOL()
here. Just verified it locally. I'll remove it in v4.