On Sat, May 12, 2007 at 12:41:54PM +0200, Rafael J. Wysocki wrote: > > Still, the following scenario is possible while we're freezing users space > tasks: > > (1) user space task calls daemonize() > (2) freezer checks if this is a user space task and the test returns 'true' > (3) task calls exit_mm() and clears its TIF_FREEZE > (4) freezer sets TIF_FREEZE for the task > (5) task calls try_to_freeze() and freezes itself (bad!) > > To prevent this from happening, I think, we should acquire task_lock() around > the entire block in which the test is made and TIF_FREEZE is set for the task, > so something more sophisticated than > freezer-read-pf_borrowed_mm-in-a-nonracy-way.patch is needed. >
Hmmm, turns out Linus was right, after all! The caller needs to acquire the task_lock(). > Well, I think we should ask Andrew to drop this patch and try to address the > issue in the next series of patches. I think it's a good idea. I would want to review the patches again. The more I look at them, the better I seem to understand the subtleties in the freezer code. > > Greetings, > Rafael Thanks and Regards gautham. -- Gautham R Shenoy Linux Technology Center IBM India. "Freedom comes with a price tag of responsibility, which is still a bargain, because Freedom is priceless!" - 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/
