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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 5/9] freezer: set default freeze priority for PF_SUSPEND_TASK processes Message-ID: <20250811094651.GD11928@redhat.com> References: <20250807121418.139765-1-zhangzihuan@kylinos.cn> <20250807121418.139765-6-zhangzihuan@kylinos.cn> <20250808143943.GB21685@redhat.com> <0754e3e3-9c47-47d5-81d9-4574e5b413bc@kylinos.cn> <20250811093216.GB11928@redhat.com> <428beb0d-2484-4816-86c3-01e91bd7715a@kylinos.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <428beb0d-2484-4816-86c3-01e91bd7715a@kylinos.cn> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 352A9140002 X-Stat-Signature: bwy578jw6t4s6fkkjejdmc1itr8sfdtf X-Rspam-User: X-HE-Tag: 1754905712-473064 X-HE-Meta: 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 zTwM5EBz +c/QBl65HtnUjrOJZdCX6a1X1BPd98UORn8jbSMVGNXYPSp2zPoY5bJlHnGh0hzxd8hF81WfDzXpssLOxYavBIEhMBnI5pUOoFTtmq1lga1ojy38kdZj80YJ9tK4eMP3HoxgE6Z4ylAGaQwcJNIgwWTDYXoc+nemlTRAdIeRCmGgnLpX7MhzkqhOwBKVKEhZ2RzSY2EmNdnFKml9VtjN3OcUQm+ERVSytzedY1O5I4bxDpu9zpPaqj3Hs/Dz8wLCvPafKCrPwvLwozJoHcZ/vmOESRe72U5If/AchLUysDDwF5sJO8LoJujqrEA9POQXzTJ9kB2QybZd1jBYi/lzF2yz4GuFw6z7zOLcvQRQkdq15jyw21r/TpYPa2Edzu0ozZjJymdzh4ArkmfE= 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 2025/8/11 17:32, Oleg Nesterov 写道: > >On 08/11, Zihuan Zhang wrote: > >>在 2025/8/8 22:39, Oleg Nesterov 写道: > >>>On 08/07, Zihuan Zhang wrote: > >>>>--- a/kernel/power/process.c > >>>>+++ b/kernel/power/process.c > >>>>@@ -147,6 +147,7 @@ int freeze_processes(void) > >>>> > >>>> pm_wakeup_clear(0); > >>>> pm_freezing = true; > >>>>+ freeze_set_default_priority(current, FREEZE_PRIORITY_NEVER); > >>>But why? > >>> > >>>Again, freeze_task() will return false anyway, this process is > >>>PF_SUSPEND_TASK. > >>I  think there is resaon put it here. For example, systemd-sleep is a > >>user-space process that executes the suspend flow. > >> > >>  If we don’t set its freeze priority explicitly, our current code may end up > >>with this user process being the last one that cannot freeze. > >How so? sorry I don't follow. > > The problem is in this part: > > +            if (user_only && !(p->flags & PF_KTHREAD) && round < > p->freeze_priority) > +                continue; > > PF_SUSPEND_TASK is a user process, so it meets the “needs freezing” > condition and todo gets incremented. ^^^^^^^^^^^^^^^^^^^^^^^^^ No. if (p == current || !freeze_task(p)) continue; todo++; Again, again, freeze_task(p) returns false. > But it actually doesn’t need to freeze, > so resulting in an infinite loop I don't think so. Oleg.