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Wysocki" , Peter Zijlstra , Oleg Nesterov , David Hildenbrand , Michal Hocko , Jonathan Corbet Cc: Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , len brown , pavel machek , Kees Cook , Andrew Morton , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Catalin Marinas , Nico Pache , xu xin , wangfushuai , Andrii Nakryiko , Christian Brauner , Thomas Gleixner , Jeff Layton , Al Viro , Adrian Ratiu , linux-pm@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Zihuan Zhang Subject: [RFC PATCH v1 6/9] freezer: Set default freeze priority for zombie tasks Date: Thu, 7 Aug 2025 20:14:15 +0800 Message-Id: <20250807121418.139765-7-zhangzihuan@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20250807121418.139765-1-zhangzihuan@kylinos.cn> References: <20250807121418.139765-1-zhangzihuan@kylinos.cn> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C25AC4000D X-Stat-Signature: 8fofowzbuaggxwfa39ockh6k3kxtgn8m X-Rspam-User: X-HE-Tag: 1754568907-629801 X-HE-Meta: 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 LBkzghIM sXxKmbZYUmkwXItk06s4nr05n+wCyhg0d1LnpQvRWYUB45jOS2Io9D5O3Ozr6r2HaAZ7EfN5uUFol3UwRAsFo6IMB5w== 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: Zombie processes are not subject to freezing, but they are still part of the global task list. During freeze traversal, tasks are examined for priority and eligibility, which may involve unnecessary locking even for non-freezable tasks like zombies. This patch assigns a default freeze priority to zombie tasks during exit, so that the freezer can skip priority setup and locking for them in subsequent iterations. This helps reduce overhead during freeze traversal, especially when many zombie processes exist in the system. Signed-off-by: Zihuan Zhang --- kernel/sched/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index be00629f0ba4..5a26d7511047 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include #include @@ -6980,6 +6981,7 @@ void __noreturn do_task_dead(void) current->flags |=3D PF_NOFREEZE; =20 __schedule(SM_NONE); + freeze_set_default_priority(current, FREEZE_PRIORITY_NEVER); BUG(); =20 /* Avoid "noreturn function does return" - but don't continue if BUG() = is a NOP: */ --=20 2.25.1