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[v2] PM / Freezer: Skip dead/zombie processes

Message ID 20250523034253.88083-1-zhangzihuan@kylinos.cn
State New
Headers show
Series [v2] PM / Freezer: Skip dead/zombie processes | expand

Commit Message

Zihuan Zhang May 23, 2025, 3:42 a.m. UTC
ZOMBIE (exit_state == EXIT_ZOMBIE) and DEAD (exit_state == EXIT_DEAD)
processes have already finished execution and will not be scheduled again.

In the context of system suspend (e.g., S3), attempting to freeze such
processes is unnecessary. Moreover, freezing them can obscure suspend
diagnostics and delay resume if they appear "stuck" in logs.

This patch introduces an early check for `p->exit_state != 0` in
`try_to_freeze_tasks()` and skips freezing for such tasks. This is a safe
optimization because:

 - They hold no running resources
 - Their `task_struct` is only waiting to be collected or freed

Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>

Changes in v2:
- Simplified code, added judgment of dead processes
- Rewrite changelogs
---
 kernel/power/process.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 66ac067d9ae6..82528a79d46a 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -51,7 +51,7 @@  static int try_to_freeze_tasks(bool user_only)
 		todo = 0;
 		read_lock(&tasklist_lock);
 		for_each_process_thread(g, p) {
-			if (p == current || !freeze_task(p))
+			if (p == current || p->exit_state || !freeze_task(p))
 				continue;
 
 			todo++;