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Merge tag 'sched_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull scheduler fix from Borislav Petkov:
 "Fix task exposure order when forking tasks"

* tag 'sched_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix yet more sched_fork() races
This commit is contained in:
Linus Torvalds
2022-02-20 12:40:20 -08:00
parent 6e8e752f70 b1e8206582
commit 0b0894ff78
3 changed files with 35 additions and 16 deletions
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13
kernel/fork.c
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@@ -2266,6 +2266,17 @@ static __latent_entropy struct task_struct *copy_process(
if (retval)
goto bad_fork_put_pidfd;
/*
* Now that the cgroups are pinned, re-clone the parent cgroup and put
* the new task on the correct runqueue. All this *before* the task
* becomes visible.
*
* This isn't part of ->can_fork() because while the re-cloning is
* cgroup specific, it unconditionally needs to place the task on a
* runqueue.
*/
sched_cgroup_fork(p, args);
/*
* From this point on we must avoid any synchronous user-space
* communication until we take the tasklist-lock. In particular, we do
@@ -2375,7 +2386,7 @@ static __latent_entropy struct task_struct *copy_process(
fd_install(pidfd, pidfile);
proc_fork_connector(p);
sched_post_fork(p, args);
sched_post_fork(p);
cgroup_post_fork(p, args);
perf_event_fork(p);