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Wysocki" , Peter Zijlstra , David Hildenbrand , Michal Hocko , Jonathan Corbet , 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 Subject: Re: [RFC PATCH v1 6/9] freezer: Set default freeze priority for zombie tasks Message-ID: <20250811094252.GC11928@redhat.com> References: <20250807121418.139765-1-zhangzihuan@kylinos.cn> <20250807121418.139765-7-zhangzihuan@kylinos.cn> <20250808142948.GA21685@redhat.com> <393a4509-9b05-45b8-8496-699ace9a5438@kylinos.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <393a4509-9b05-45b8-8496-699ace9a5438@kylinos.cn> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Stat-Signature: 1ws9sih8u4z9zdy1sftpkyjmmt8n5x15 X-Rspamd-Queue-Id: 7AEB580004 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1754905469-87167 X-HE-Meta: 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 1nFTAjTV yGQxQE7DamKFBjR/dilM/ze3skcIi5vfRDHV6TfAlCul/5et/iuMO1+LhNZv5kdeGSZWTFDrdYgBQcI+tWwZzxwx3Wk31Fe5UHJJjRCWI6P/SsKaTjEsNsdGq503dkrmZec0pppYjrLm1BBRyAwVkxckX/1akLFnDvEmazn0gLR2jcA/J6+EeGWzFsIdQ7ra394FpmdItgJShL2EunpRIAYcAP9yise0KqFn5yU64/ISAD/W00Nsp0ACp3ep/cP96cupjKgvq2Shz4dfGsDG0YED7kulUrg62yBFpuX8vHuxKJL/BrmwESCm501KrkaYKK5PGD+dJD9TPL02qkKsTtYMxYtqUzNLrfNInqWl1FMR+pU7G2etc7T/H7cYrAnOmjZ3HRfRZF+BEXLgudURRlp3vqCum5aVNUJ5bQffJHlWzFkA= 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 08/11, Zihuan Zhang wrote: > > 在 2025/8/8 22:29, Oleg Nesterov 写道: > >On 08/07, Zihuan Zhang wrote: > >>@@ -6980,6 +6981,7 @@ void __noreturn do_task_dead(void) > >> current->flags |= PF_NOFREEZE; > >> > >> __schedule(SM_NONE); > >>+ freeze_set_default_priority(current, FREEZE_PRIORITY_NEVER); > >> BUG(); > >But this change has no effect? > > > >Firstly, this last __schedule() should not return, note the BUG() we have. > > > >Secondly, this zombie is already PF_NOFREEZE, freeze_task() will return > >false anyway. > Sorry, but in our tests with a large number of zombie tasks, returning early > reduced the overhead. Even though freeze_task() would return false for > PF_NOFREEZE, skipping the extra path still saved time in our suspend/freezer https://lore.kernel.org/all/20250707084214.GD1613200@noisy.programming.kicks-ass.net/ Anyway the patch makes no sense in its current form, see my note about __schedule() above. Oleg.