Re: [PATCH 1/1] PM: fix oops in suspend/hibernate code

Jiri Slaby
2011-01-06T16:09:46Z

On 01/06/2011 04:57 PM, Rafael J. Wysocki wrote:
> On Thursday, January 06, 2011, Jiri Slaby wrote:
>> When ioremap fails (which might happen for some reason),
>
> If it happens, something is seriously wrong (see below).

I agree that something is broken, however ioremap may fail for dozen of
reasons. Ignoring the retval is a *bad* idea and it took me a while to
sort out what is wrong. Especially if one has no console like throughout
suspend. If it was handled properly, I would know immediately. (There
should be a message printed out which I forgot to add.)

> BTW, to keep things in context, please post fixes like this in the same thread
> in which you reported the problem. At lease please retain the CC list from
> there.

I actually did, there is:
In-Reply-To: <201101060028.43342.rjw@sisk.pl>
and it successfully threaded to the conversation for me in TB.

>> we nicely oops in suspend_nvs_save due to NULL dereference by memcpy in
>> there. Fail gracefully instead.
>>
>> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
>> Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
>> ---
>> drivers/acpi/sleep.c | 5 ++---
>> include/linux/suspend.h | 4 ++--
>> kernel/power/nvs.c | 8 +++++++-
>> 3 files changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
>> index c423231..f94c9a9 100644
>> --- a/drivers/acpi/sleep.c
>> +++ b/drivers/acpi/sleep.c
>> @@ -124,8 +124,7 @@ static int acpi_pm_freeze(void)
>> static int acpi_pm_pre_suspend(void)
>> {
>> acpi_pm_freeze();
>> - suspend_nvs_save();
>> - return 0;
>> + return suspend_nvs_save();
>> }
>>
>> /**
>> @@ -151,7 +150,7 @@ static int acpi_pm_prepare(void)
>> {
>> int error = __acpi_pm_prepare();
>> if (!error)
>> - acpi_pm_pre_suspend();
>> + error = acpi_pm_pre_suspend();
>>
>> return error;
>> }
>> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
>> index c1f4998..3ac2551 100644
>> --- a/include/linux/suspend.h
>> +++ b/include/linux/suspend.h
>> @@ -262,7 +262,7 @@ static inline bool system_entering_hibernation(void) { return false; }
>> extern int suspend_nvs_register(unsigned long start, unsigned long size);
>> extern int suspend_nvs_alloc(void);
>> extern void suspend_nvs_free(void);
>> -extern void suspend_nvs_save(void);
>> +extern int suspend_nvs_save(void);
>> extern void suspend_nvs_restore(void);
>> #else /* CONFIG_SUSPEND_NVS */
>> static inline int suspend_nvs_register(unsigned long a, unsigned long b)
>> @@ -271,7 +271,7 @@ static inline int suspend_nvs_register(unsigned long a, unsigned long b)
>> }
>> static inline int suspend_nvs_alloc(void) { return 0; }
>> static inline void suspend_nvs_free(void) {}
>> -static inline void suspend_nvs_save(void) {}
>> +static inline int suspend_nvs_save(void) {}
>> static inline void suspend_nvs_restore(void) {}
>> #endif /* CONFIG_SUSPEND_NVS */
>>
>> diff --git a/kernel/power/nvs.c b/kernel/power/nvs.c
>> index 1836db6..57c6fab 100644
>> --- a/kernel/power/nvs.c
>> +++ b/kernel/power/nvs.c
>> @@ -105,7 +105,7 @@ int suspend_nvs_alloc(void)
>> /**
>> * suspend_nvs_save - save NVS memory regions
>> */
>> -void suspend_nvs_save(void)
>> +int suspend_nvs_save(void)
>> {
>> struct nvs_page *entry;
>>
>> @@ -114,8 +114,14 @@ void suspend_nvs_save(void)
>> list_for_each_entry(entry, &nvs_list, node)
>> if (entry->data) {
>> entry->kaddr = ioremap(entry->phys_start, entry->size);
>
> I wonder what happens if you simply change the ioremap() here to
> ioremap_nocache() without any other modifications?

ioremap *is* ioremap_nocache on x86. And that's the conflict it
complains about I guess? Don't you mean ioremap_cache?

> It _really_ shouldn't fail here, because the NVS pages are known to be present.

It fails because of conflicting maps as can be seen in the photo. At
least I think so.

regards,
--
js