On Thu, Sep 08 2005, Giancarlo Formicuccia wrote: > Hi, > [please CC me in any reply] > I'm not sure that dup_task_struct() must copy the fs_excl field. This can > leads to > problems if do_fork() is somehow called while fs_excl!=0. > For example, the jffs2 code creates a kernel thread > (jffs2_garbage_collect_thread) > in a path where lock_super() is held (i.e. by do_remount_sb, during -o > remount,rw). > When the new thread expires, a badness happens (kernel/exit.c:787). This > problem > was observed by a couple of people and can be easily reproduced: > http://lists.infradead.org/pipermail/linux-mtd/2005-August/013487.html > http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2005-September/031109.html > > At first glance, I'd simply set fs_excl to 0 for every new thread in > dup_task_struct: > > --- linux-2.6.13/kernel/fork.c 2005-08-29 01:41:01.000000000 +0200 > +++ linux-2.6.13-new/kernel/fork.c 2005-09-07 17:06:23.000000000 +0200 > @@ -173,6 +173,7 @@ static struct task_struct *dup_task_stru > *tsk = *orig; > tsk->thread_info = ti; > ti->task = tsk; > + atomic_set(&tsk->fs_excl, 0); > > /* One for us, one for whoever does the "release_task()" (usually > parent) */ > atomic_set(&tsk->usage,2); > > but I've a doubt about the WARN_ON in exit.c being actually here to report > these > kernel_thread() users (like jffs2)... > > Any comment/suggestion?
Patch is correct, that is definitely an oversight! Acked-by: Jens Axboe <[EMAIL PROTECTED]> -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
