lists.openwall.net | 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 linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 24 Apr 2007 03:42:20 -0700 From: Andrew Morton <akpm@...ux-foundation.org> To: ebiederm@...ssion.com (Eric W. Biederman) Cc: Oleg Nesterov <oleg@...sign.ru>, Davide Libenzi <davidel@...ilserver.org>, Ingo Molnar <mingo@...e.hu>, Linus Torvalds <torvalds@...ux-foundation.org>, "Rafael J. Wysocki" <rjw@...k.pl>, Roland McGrath <roland@...hat.com>, Rusty Russell <rusty@...tcorp.com.au>, linux-kernel@...r.kernel.org, <linux-arch@...r.kernel.org> Subject: Re: [PATCH] kthread: Enhance kthread_stop to abort interruptible sleeps On Tue, 24 Apr 2007 04:30:22 -0600 ebiederm@...ssion.com (Eric W. Biederman) wrote: > Andrew Morton <akpm@...ux-foundation.org> writes: > > > On Fri, 13 Apr 2007 21:13:13 -0600 ebiederm@...ssion.com (Eric W. Biederman) > > wrote: > > > >> This patch reworks kthread_stop so it is more flexible and it causes > >> the target kthread to abort interruptible sleeps. Allowing a larger > >> class of kernel threads to use to the kthread API. > >> > >> The changes start by defining TIF_KTHREAD_STOP on all architectures. > >> TIF_KTHREAD_STOP is a per process flag that I can set from another > >> process to indicate that a kernel thread should stop. > >> > >> wake_up_process in kthread_stop has been replaced by signal_wake_up > >> ensuring that the kernel thread if sleeping is woken up in a timely > >> manner and with TIF_SIGNAL_PENDING set, which causes us to break out > >> of interruptible sleeps. > >> > >> recalc_signal_pending was modified to keep TIF_SIGNAL_PENDING set for > >> as long as TIF_KTHREAD_STOP is set. > >> > >> Arbitrary paths to do_exit are now allowed. I have placed a > >> completion on the thread stack and pointed vfork_done at it, when the > >> mm_release is called from do_exit the completion will be called. > >> Since the completion is stored on the stack it is important that > >> kthread() now calls do_exit ensuring the stack frame that holds the > >> completion is never released, and so that our exit_code is certain to > >> make it unchanged all the way to do_exit. > >> > >> To allow kthread_stop to read the process exit code when exit_mm wakes > >> it up I have moved the setting of exit_code to the beginning of > >> do_exit. > > > > This patch causes this oops: http://userweb.kernel.org/~akpm/s5000508.jpg > > with this config: http://userweb.kernel.org/~akpm/config-x.txt > > Thanks. If I am reading the oops properly this happened during bootup and > vfork_done was set to NULL? Yes, it was fairly early in boot. I didn't check what we're oopsing on. > The NULL vfork_done is really weird as exec is the only thing that sets > vfork_done to NULL. > > Either I've got a stupid bug in there somewhere or we have just found > the weirdest memory stomp. I will take a look and see if I can reproduce > this shortly. That was on a Fedora Core 3 machine. One of those older distros I keep around to trip people up. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists