linux-kernel - Re: [PATCH] uprobes: fix incorrect lockdep condition in filter

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Message-ID: <aXoUOEhDfncEkC-f@redhat.com>
Date: Wed, 28 Jan 2026 14:50:48 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Breno Leitao <leitao@...ian.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	James Clark <james.clark@...aro.org>,
	Andrii Nakryiko <andrii@...nel.org>, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, kernel-team@...a.com,
	stable@...r.kernel.org
Subject: Re: [PATCH] uprobes: fix incorrect lockdep condition in
 filter_chain()

On 01/28, Breno Leitao wrote:
>
> The list_for_each_entry_rcu() in filter_chain() uses
> rcu_read_lock_trace_held() as the lockdep condition, but the function
> holds consumer_rwsem, not the RCU trace lock.
> 
> This gives me the following output when running with some locking debug
> option enabled:
> 
>   kernel/events/uprobes.c:1141 RCU-list traversed in non-reader section!!
>     filter_chain
>     register_for_each_vma
>     uprobe_unregister_nosync
>     __probe_event_disable
>
> Remove the incorrect lockdep condition since the rwsem provides
> sufficient protection for the list traversal.

I hope Andrii will recheck, but looks obviously correct to me.

> Fixes: 87195a1ee332a ("uprobes: switch to RCU Tasks Trace flavor for better performance")

This commit just change the __list_check_rcu() condition...

Perhaps
Fixes: cc01bd044e6a ("uprobes: travers uprobe's consumer list locklessly under SRCU protection")

makes more sense?

Acked-by: Oleg Nesterov <oleg@...hat.com>