tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
1
fork

Configure Feed

Select the types of activity you want to include in your feed.

freezer: Clarify that only cgroup1 freezer uses PM freezer

cgroup1 freezer piggybacks on the PM freezer, which inadvertently allowed
userspace to produce uninterruptible tasks at will. To avoid the issue,
cgroup2 freezer switched to a separate job control based mechanism. While
this happened a long time ago, the code and comment haven't been updated
making it confusing to people who aren't familiar with the history.

Rename cgroup_freezing() to cgroup1_freezing() and update comments on top of
freezing() and frozen() to clarify that cgroup2 freezer isn't covered by the
PM freezer mechanism.

Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Qu Wenruo <wqu@suse.com>
Link: https://patch.msgid.link/aPZ3q6Hm865NicBC@slm.duckdns.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

authored by

Tejun Heo and committed by
Rafael J. Wysocki 8e4ec907 ea358066

+10 -6
+8 -4
include/linux/freezer.h
··· 22 22 extern unsigned int freeze_timeout_msecs; 23 23 24 24 /* 25 - * Check if a process has been frozen 25 + * Check if a process has been frozen for PM or cgroup1 freezer. Note that 26 + * cgroup2 freezer uses the job control mechanism and does not interact with 27 + * the PM freezer. 26 28 */ 27 29 extern bool frozen(struct task_struct *p); 28 30 29 31 extern bool freezing_slow_path(struct task_struct *p); 30 32 31 33 /* 32 - * Check if there is a request to freeze a process 34 + * Check if there is a request to freeze a task from PM or cgroup1 freezer. 35 + * Note that cgroup2 freezer uses the job control mechanism and does not 36 + * interact with the PM freezer. 33 37 */ 34 38 static inline bool freezing(struct task_struct *p) 35 39 { ··· 67 63 extern bool set_freezable(void); 68 64 69 65 #ifdef CONFIG_CGROUP_FREEZER 70 - extern bool cgroup_freezing(struct task_struct *task); 66 + extern bool cgroup1_freezing(struct task_struct *task); 71 67 #else /* !CONFIG_CGROUP_FREEZER */ 72 - static inline bool cgroup_freezing(struct task_struct *task) 68 + static inline bool cgroup1_freezing(struct task_struct *task) 73 69 { 74 70 return false; 75 71 }
+1 -1
kernel/cgroup/legacy_freezer.c
··· 63 63 return css_freezer(freezer->css.parent); 64 64 } 65 65 66 - bool cgroup_freezing(struct task_struct *task) 66 + bool cgroup1_freezing(struct task_struct *task) 67 67 { 68 68 bool ret; 69 69
+1 -1
kernel/freezer.c
··· 44 44 if (tsk_is_oom_victim(p)) 45 45 return false; 46 46 47 - if (pm_nosig_freezing || cgroup_freezing(p)) 47 + if (pm_nosig_freezing || cgroup1_freezing(p)) 48 48 return true; 49 49 50 50 if (pm_freezing && !(p->flags & PF_KTHREAD))