Revision d966564fcdc19e13eb6ba1fbe6b8101070339c3d authored by Linus Torvalds on 09 February 2017, 02:08:29 UTC, committed by Linus Torvalds on 09 February 2017, 02:08:29 UTC
This reverts commit 020eb3daaba2857b32c4cf4c82f503d6a00a67de. Gabriel C reports that it causes his machine to not boot, and we haven't tracked down the reason for it yet. Since the bug it fixes has been around for a longish time, we're better off reverting the fix for now. Gabriel says: "It hangs early and freezes with a lot RCU warnings. I bisected it down to : > Ruslan Ruslichenko (1): > x86/ioapic: Restore IO-APIC irq_chip retrigger callback Reverting this one fixes the problem for me.. The box is a PRIMERGY TX200 S5 , 2 socket , 2 x E5520 CPU(s) installed" and Ruslan and Thomas are currently stumped. Reported-and-bisected-by: Gabriel C <nix.or.die@gmail.com> Cc: Ruslan Ruslichenko <rruslich@cisco.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org # for the backport of the original commit Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 3b802c9
is_single_threaded.c
/* Function to determine if a thread group is single threaded or not
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* - Derived from security/selinux/hooks.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/sched.h>
/*
* Returns true if the task does not share ->mm with another thread/process.
*/
bool current_is_single_threaded(void)
{
struct task_struct *task = current;
struct mm_struct *mm = task->mm;
struct task_struct *p, *t;
bool ret;
if (atomic_read(&task->signal->live) != 1)
return false;
if (atomic_read(&mm->mm_users) == 1)
return true;
ret = false;
rcu_read_lock();
for_each_process(p) {
if (unlikely(p->flags & PF_KTHREAD))
continue;
if (unlikely(p == task->group_leader))
continue;
for_each_thread(p, t) {
if (unlikely(t->mm == mm))
goto found;
if (likely(t->mm))
break;
/*
* t->mm == NULL. Make sure next_thread/next_task
* will see other CLONE_VM tasks which might be
* forked before exiting.
*/
smp_rmb();
}
}
ret = true;
found:
rcu_read_unlock();
return ret;
}
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