Messages in this thread | | | Date | Mon, 1 Aug 2011 22:01:51 +0400 | From | Vasiliy Kulikov <> | Subject | initcall dependency problem (ns vs. threads) |
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Hi,
There were reported problems with recent shm changes, by Manuel Lauss (on MIPS), Richard Weinberger (on UML), and Marc Zyngier (on ARM).
https://lkml.org/lkml/2011/8/1/149 https://lkml.org/lkml/2011/8/1/162 https://lkml.org/lkml/2011/8/1/210
The problem became visible on this patch:
commit 5774ed014f02120db9a6945a1ecebeb97c2acccb Author: Vasiliy Kulikov <segoon@openwall.com> Date: Fri Jul 29 03:55:31 2011 +0400
shm: handle separate PID namespaces case
It started to use &shm_ids(ns).rw_mutex, which is not initialized yet. Init IPC namespace is initialized as initcall() and some threads are created as early_initcall().
I threat it is a dependency bug in the core kernel - kernel threads should be able to use any namespace information, but currently there is a race between namespace initialization code (which is initcall) and kernel threads (which are early_initcall).
I don't feel enough experienced in init code dependencies, so I report it to you.
static int __init kernel_init(void * unused) { ... do_pre_smp_initcalls(); << threads start here ... do_basic_setup();
static void __init do_basic_setup(void) { cpuset_init_smp(); usermodehelper_init(); init_tmpfs(); driver_init(); init_irq_proc(); do_ctors(); do_initcalls(); << namespace init here }
Thanks,
-- Vasiliy
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