[PATCH] acpi/battery: fix async boot oops

From: Vegard Nossum
Date: Tue Apr 07 2009 - 04:55:38 EST


2009/4/6 Arkadiusz Miskiewicz <a.miskiewicz@xxxxxxxxx>:
>
> Pulled Linus git few minutes ago and new oops at boot (happens on every boot).
> Yesterday git version was fine. Oopsed just while/after udev started.

[...]

> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffffa00fd040>] 0xffffffffa00fd040
> PGD 13998a067 PUD 139979067 PMD 0
> Oops: 0002 [#1] PREEMPT SMP
> last sysfs file: /sys/devices/platform/i8042/modalias
> CPU 0
> Modules linked in: evdev(+) cfg80211(+) battery ac button crc_itu_t xfs exportfs scsi_wait_scan sd_mod crc_t10dif ahci libata scsi_mod
> Pid: 3167, comm: async/0 Not tainted 2.6.29 #12 2764CTO
> RIP: 0010:[<ffffffffa00fd040>] [<ffffffffa00fd040>] 0xffffffffa00fd040

What happens is that the battery module's init sections are being freed
before the async callback (which was marked __init) has run. This theory
is supported by the fact that the bad RIP value is a vmalloc address.

The immediate fix is to make this a non-init call.

(A better long-term fix is of course to wait with init-section unloading
until a module's async initcalls have been run, which would allow us to
discard this function which is still only run once, after all. Perhaps a
new async_initcall() function for the async/module API, if this is needed
for other modules in the future?)

Reported-by: Arkadiusz Miskiewicz <a.miskiewicz@xxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx>
---
drivers/acpi/battery.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index b0de631..3c7d894 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -903,7 +903,7 @@ static struct acpi_driver acpi_battery_driver = {
},
};

-static void __init acpi_battery_init_async(void *unused, async_cookie_t cookie)
+static void acpi_battery_init_async(void *unused, async_cookie_t cookie)
{
if (acpi_disabled)
return;
--
1.6.0.6

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