lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 20 Oct 2014 11:13:11 +0200
From:	Peter Zijlstra <>
To:	Oleg Nesterov <>
Cc:	Kirill Tkhai <>,
	Kirill Tkhai <>,
	"" <>,
	Ingo Molnar <>,
	Vladimir Davydov <>
Subject: Re: [PATCH] sched/numa: fix unsafe get_task_struct() in

OK, I think I'm finally awake enough to see what you're all talking
about :-)

On Sun, Oct 19, 2014 at 09:37:44PM +0200, Oleg Nesterov wrote:
> > > RT tree has:
> > >
> > >
> > > tree/patches/sched-delay-put-task.patch

(answering the other email asking about this)

RT does this because we call put_task_struct() with preempt disabled and
on RT the memory allocator has sleeping locks.

> > Yes, and this obviously implies more rcu callbacks in flight, and another
> > gp before __put_task_struct(). but may be we will need to do this anyway...
> Forgot to mention... Or we can make task_struct_cachep SLAB_DESTROY_BY_RCU,
> in this case ->curr (or any other "task_struct *" ponter) can not go away
> under rcu_read_lock(). task_numa_compare() still needs the PF_EXITING check,
> but we do not need to recheck ->curr or probe_kernel_read().

I think I would prefer SLAB_DESTROY_BY_RCU for this, because as you
pointed out, I'm not sure mainline would like the extra callbacks.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists