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[46.135.95.94]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5dcf9f6fa69sm1121849a12.73.2025.02.06.08.44.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2025 08:44:39 -0800 (PST) From: Mateusz Guzik To: ebiederm@xmission.com, oleg@redhat.com Cc: brauner@kernel.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mateusz Guzik Subject: [PATCH v6 1/5] exit: perform add_device_randomness() without tasklist_lock Date: Thu, 6 Feb 2025 17:44:10 +0100 Message-ID: <20250206164415.450051-2-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250206164415.450051-1-mjguzik@gmail.com> References: <20250206164415.450051-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Parallel calls to add_device_randomness() contend on their own. The clone side aleady runs outside of tasklist_lock, which in turn means any caller on the exit side extends the tasklist_lock hold time while contending on the random-private lock. Reviewed-by: Oleg Nesterov Signed-off-by: Mateusz Guzik --- kernel/exit.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 3485e5fc499e..9d7acd7b0040 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -174,9 +174,6 @@ static void __exit_signal(struct task_struct *tsk) sig->curr_target =3D next_thread(tsk); } =20 - add_device_randomness((const void*) &tsk->se.sum_exec_runtime, - sizeof(unsigned long long)); - /* * Accumulate here the counters for all threads as they die. We could * skip the group leader because it is the last user of signal_struct, @@ -278,6 +275,8 @@ void release_task(struct task_struct *p) write_unlock_irq(&tasklist_lock); proc_flush_pid(thread_pid); put_pid(thread_pid); + add_device_randomness(&p->se.sum_exec_runtime, + sizeof(p->se.sum_exec_runtime)); release_thread(p); put_task_struct_rcu_user(p); =20 --=20 2.43.0