Commit-ID: 3c9b2c3d64a49f264422d7743599cf7f6535972d Gitweb: http://git.kernel.org/tip/3c9b2c3d64a49f264422d7743599cf7f6535972d Author: Peter Zijlstra <[email protected]> AuthorDate: Wed, 24 Sep 2014 10:18:53 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 28 Oct 2014 10:56:30 +0100
sched, modules: Fix nested sleep in add_unformed_module() This is a genuine bug in add_unformed_module(), we cannot use blocking primitives inside a wait loop. So rewrite the wait_event_interruptible() usage to use the fresh wait_woken() stuff. Reported-by: Fengguang Wu <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: Rusty Russell <[email protected]> Cc: [email protected] Cc: Linus Torvalds <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Link: http://lkml.kernel.org/r/[email protected] [ So this is probably complex to backport and the race wasn't reported AFAIK, so not marked for -stable. ] Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> --- kernel/module.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 88cec1d..e52a873 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3097,6 +3097,32 @@ static int may_init_module(void) } /* + * Can't use wait_event_interruptible() because our condition + * 'finished_loading()' contains a blocking primitive itself (mutex_lock). + */ +static int wait_finished_loading(struct module *mod) +{ + DEFINE_WAIT_FUNC(wait, woken_wake_function); + int ret = 0; + + add_wait_queue(&module_wq, &wait); + for (;;) { + if (finished_loading(mod->name)) + break; + + if (signal_pending(current)) { + ret = -ERESTARTSYS; + break; + } + + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + } + remove_wait_queue(&module_wq, &wait); + + return ret; +} + +/* * We try to place it in the list now to make sure it's unique before * we dedicate too many resources. In particular, temporary percpu * memory exhaustion. @@ -3116,8 +3142,8 @@ again: || old->state == MODULE_STATE_UNFORMED) { /* Wait in case it fails to load. */ mutex_unlock(&module_mutex); - err = wait_event_interruptible(module_wq, - finished_loading(mod->name)); + + err = wait_finished_loading(mod); if (err) goto out_unlocked; goto again; -- 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/
