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Howlett" , maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] maple_tree: fix tracepoint string pointers Message-Id: <20251030193206.22bb773e697b6cc385d5aa67@linux-foundation.org> In-Reply-To: <20251030155537.87972-1-martin@kaiser.cx> References: <20251030155537.87972-1-martin@kaiser.cx> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 4E1E62000A X-Rspamd-Server: rspam03 X-Stat-Signature: zod88kkaq3yroh3gsmctmy4s38crzhke X-HE-Tag: 1761877928-228203 X-HE-Meta: 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 XSB25xYt omZeh20nYLNO3qtevqjZwEaWPrIeidD0RmerjBsTYle9fEz55B3dg1oGqZDnjRCW11q43B1Pc9Ac6iC9zfyfXqU6q5TIHW1GR4qBJBRpRT9eDwCsBq0fIx0icSgV+MRi2098AhwFDODNWIxqSKJ/gzLb/lJt1jSgfUWnWavnINaDhrnDUep82qs+eyw6/ke4tR3G3ClXYPZR3/KLb/ktfl+ngrBt/LuQb7Ex9wsRzMHAUZkr31cFRSCO3uvxqVnw5+ht/G03eQVwZwiGbI3hPJ7gtkc/9iz113BN+lMG1k97c/Ek= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 30 Oct 2025 16:55:05 +0100 Martin Kaiser wrote: > maple_tree tracepoints contain pointers to function names. Such a pointer > is saved when a tracepoint logs an event. There's no guarantee that it's > still valid when the event is parsed later and the pointer is dereferenced. Oh. > The kernel warns about these unsafe pointers. > > event 'ma_read' has unsafe pointer field 'fn' > WARNING: kernel/trace/trace.c:3779 at ignore_event+0x1da/0x1e4 > > Mark the function names as tracepoint_string() to fix the events. > > ... > > - trace_ma_op(__func__, mas); > + trace_ma_op(TP_FCT, mas); > What could cause the storage for __func__ to disappear as you suggest?