This is a note to let you know that I've just added the patch titled driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction to the 5.17-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: driver-core-fix-wait_for_device_probe-deferred_probe.patch and it can be found in the queue-5.17 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 3c2421a00fd64d33876b160d20d1e059492c5ffb Author: Saravana Kannan <saravanak@xxxxxxxxxx> Date: Fri Jun 3 13:31:37 2022 +0200 driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction [ Upstream commit 5ee76c256e928455212ab759c51d198fedbe7523 ] Mounting NFS rootfs was timing out when deferred_probe_timeout was non-zero [1]. This was because ip_auto_config() initcall times out waiting for the network interfaces to show up when deferred_probe_timeout was non-zero. While ip_auto_config() calls wait_for_device_probe() to make sure any currently running deferred probe work or asynchronous probe finishes, that wasn't sufficient to account for devices being deferred until deferred_probe_timeout. Commit 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires") tried to fix that by making sure wait_for_device_probe() waits for deferred_probe_timeout to expire before returning. However, if wait_for_device_probe() is called from the kernel_init() context: - Before deferred_probe_initcall() [2], it causes the boot process to hang due to a deadlock. - After deferred_probe_initcall() [3], it blocks kernel_init() from continuing till deferred_probe_timeout expires and beats the point of deferred_probe_timeout that's trying to wait for userspace to load modules. Neither of this is good. So revert the changes to wait_for_device_probe(). [1] - https://lore.kernel.org/lkml/TYAPR01MB45443DF63B9EF29054F7C41FD8C60@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ [2] - https://lore.kernel.org/lkml/YowHNo4sBjr9ijZr@dev-arch.thelio-3990X/ [3] - https://lore.kernel.org/lkml/Yo3WvGnNk3LvLb7R@xxxxxxxxxxxxx/ Fixes: 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires") Cc: John Stultz <jstultz@xxxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx> Cc: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx> Cc: Jakub Kicinski <kuba@xxxxxxxxxx> Cc: Rob Herring <robh@xxxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> Cc: Robin Murphy <robin.murphy@xxxxxxx> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> Cc: Sudeep Holla <sudeep.holla@xxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> Cc: Basil Eljuse <Basil.Eljuse@xxxxxxx> Cc: Ferry Toth <fntoth@xxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Anders Roxell <anders.roxell@xxxxxxxxxx> Cc: linux-pm@xxxxxxxxxxxxxxx Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx> Reported-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> Acked-by: John Stultz <jstultz@xxxxxxxxxx> Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220526034609.480766-2-saravanak@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Rafael J. Wysocki <rafael@xxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 977e94cf669e..86fd2ea35656 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -257,7 +257,6 @@ DEFINE_SHOW_ATTRIBUTE(deferred_devs); int driver_deferred_probe_timeout; EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); -static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue); static int __init deferred_probe_timeout_setup(char *str) { @@ -312,7 +311,6 @@ static void deferred_probe_timeout_work_func(struct work_struct *work) list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe) dev_info(p->device, "deferred probe pending\n"); mutex_unlock(&deferred_probe_mutex); - wake_up_all(&probe_timeout_waitqueue); } static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); @@ -720,9 +718,6 @@ int driver_probe_done(void) */ void wait_for_device_probe(void) { - /* wait for probe timeout */ - wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout); - /* wait for the deferred probe workqueue to finish */ flush_work(&deferred_probe_work);