From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 24 Mar 2025 20:39:27 +0000 (-0700)
Subject: Merge tag 'kernel-6.15-rc1.tasklist_lock' of git://git.kernel.org/pub/scm/linux/kerne... 
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=b0cb56cbbdb4754918c28d6d7c294d56e28a3dd5;p=users%2Fdwmw2%2Flinux.git

Merge tag 'kernel-6.15-rc1.tasklist_lock' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull tasklist_lock optimizations from Christian Brauner:
 "According to the performance testbots this brings a 23% performance
  increase when creating new processes:

   - Reduce tasklist_lock hold time on exit:
       - Perform add_device_randomness() without tasklist_lock
       - Perform free_pid() calls outside of tasklist_lock

   - Drop irq disablement around pidmap_lock

   - Add some tasklist_lock asserts

   - Call flush_sigqueue() lockless by changing release_task()

   - Don't pointlessly clear TIF_SIGPENDING in __exit_signal() ->
     clear_tsk_thread_flag()"

* tag 'kernel-6.15-rc1.tasklist_lock' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  pid: drop irq disablement around pidmap_lock
  pid: perform free_pid() calls outside of tasklist_lock
  pid: sprinkle tasklist_lock asserts
  exit: hoist get_pid() in release_task() outside of tasklist_lock
  exit: perform add_device_randomness() without tasklist_lock
  exit: kill the pointless __exit_signal()->clear_tsk_thread_flag(TIF_SIGPENDING)
  exit: change the release_task() paths to call flush_sigqueue() lockless
---

b0cb56cbbdb4754918c28d6d7c294d56e28a3dd5
diff --cc kernel/exit.c
index 683766316a3df,fd960a67a4dcc..c2e6c7b7779ff
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@@ -250,13 -249,13 +250,14 @@@ repeat
  	dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
  	rcu_read_unlock();
  
 +	pidfs_exit(p);
  	cgroup_release(p);
  
+ 	thread_pid = get_pid(p->thread_pid);
+ 
  	write_lock_irq(&tasklist_lock);
  	ptrace_release_task(p);
- 	thread_pid = get_pid(p->thread_pid);
- 	__exit_signal(p);
+ 	__exit_signal(&post, p);
  
  	/*
  	 * If we are the last non-leader member of the thread