On 09.10.19 16:43, Michal Hocko wrote:
> On Wed 09-10-19 16:24:35, David Hildenbrand wrote:
>> We should check for pfn_to_online_page() to not access uninitialized
>> memmaps. Reshuffle the code so we don't have to duplicate the error
>> message.
>>
>> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
>> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
>> ---
>> mm/memory-failure.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index 7ef849da8278..e866e6e5660b 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1253,17 +1253,19 @@ int memory_failure(unsigned long pfn, int flags)
>> if (!sysctl_memory_failure_recovery)
>> panic("Memory failure on page %lx", pfn);
>>
>> - if (!pfn_valid(pfn)) {
>> + p = pfn_to_online_page(pfn);
>> + if (!p) {
>> + if (pfn_valid(pfn)) {
>> + pgmap = get_dev_pagemap(pfn, NULL);
>> + if (pgmap)
>> + return memory_failure_dev_pagemap(pfn, flags,
>> + pgmap);
>> + }
>> pr_err("Memory failure: %#lx: memory outside kernel control\n",
>> pfn);
>> return -ENXIO;
>
> Don't we need that earlier at hwpoison_inject level?
>
Theoretically yes, this is another instance. But pfn_to_online_page(pfn)
alone would not be sufficient as discussed. We would, again, have to
special-case ZONE_DEVICE via things like get_dev_pagemap() ...
But mm/hwpoison-inject.c:hwpoison_inject() is a pure debug feature either way:
/*
* Note that the below poison/unpoison interfaces do not involve
* hardware status change, hence do not require hardware support.
* They are mainly for testing hwpoison in software level.
*/
So it's not that bad compared to memory_failure() called from real HW or
drivers/base/memory.c:soft_offline_page_store()/hard_offline_page_store()
--
Thanks,
David / dhildenb
