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([2601:282:1e02:1040:856a:da39:d9b3:fb8f]) by smtp.googlemail.com with ESMTPSA id 586e51a60fabf-440d8297395sm10158925fac.11.2026.06.06.08.46.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 06 Jun 2026 08:46:31 -0700 (PDT) Message-ID: Date: Sat, 6 Jun 2026 09:46:29 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/9] perf sched: Clean up idle_threads entry on init failure Content-Language: en-US To: Arnaldo Carvalho de Melo , Namhyung Kim Cc: Ingo Molnar , Thomas Gleixner , James Clark , Jiri Olsa , Ian Rogers , Adrian Hunter , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , sashiko-bot , "Claude Opus 4.6" References: <20260605233837.1773732-1-acme@kernel.org> <20260605233837.1773732-6-acme@kernel.org> From: David Ahern In-Reply-To: <20260605233837.1773732-6-acme@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/5/26 5:38 PM, Arnaldo Carvalho de Melo wrote: > From: Arnaldo Carvalho de Melo > > get_idle_thread() allocates a thread via thread__new() and stores it in > idle_threads[cpu], then calls init_idle_thread() to set up the private > data. If init_idle_thread() fails (e.g. OOM for the idle_thread_runtime > struct), the function returns NULL but leaves the partially initialized > thread in idle_threads[cpu]. > > On subsequent calls for the same CPU, get_idle_thread() finds a non-NULL > idle_threads[cpu], skips allocation, and returns thread__get() on a > thread that has no priv data. Callers then get a thread whose > thread__priv() returns NULL, leading to unexpected behavior. > > Release the thread and reset the slot to NULL on init failure so the > entry doesn't persist in a corrupted state. > > Fixes: 49394a2a24c7 ("perf sched timehist: Introduce timehist command") > Reported-by: sashiko-bot > Cc: David Ahern > Cc: Namhyung Kim > Assisted-by: Claude Opus 4.6 > Signed-off-by: Arnaldo Carvalho de Melo > --- > tools/perf/builtin-sched.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > Reviewed-by: David Ahern