On 5/25/22 13:55, Oscar Salvador wrote:
> On Wed, May 25, 2022 at 09:09:09AM +0530, Anshuman Khandual wrote:
>> In check_pfn_span(), a 'reason' string is being used to recreate the caller
>> function name, while printing the warning message. It is really unnecessary
>> as the warning message could just be printed inside the caller depending on
>> the return code. Currentlyy there are just two callers for check_pfn_span()
> Currently
Ahh, will fix.
>> i.e __add_pages() and __remove_pages(). Let's clean this up.
>>
>> Cc: David Hildenbrand <david@xxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: linux-mm@xxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
>
> One could argue if this is really a cleanup.
> I kind of agree that the "reason" thingy is a bit shaky, but instead of having a
> single place where we call WARN(), we now do have two.
check_pfn_span() is basically ensuring minimum alignment for both pfn and
nr_pages. Resulting error message when this alignment check does not hold
true, is caller specific than not.
>
>> ---
>> mm/memory_hotplug.c | 19 +++++++++----------
>> 1 file changed, 9 insertions(+), 10 deletions(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 416b38ca8def..9b3d7295ef93 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -220,8 +220,7 @@ static void release_memory_resource(struct resource *res)
>> kfree(res);
>> }
>>
>> -static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
>> - const char *reason)
>> +static int check_pfn_span(unsigned long pfn, unsigned long nr_pages)
>> {
>> /*
>> * Disallow all operations smaller than a sub-section and only
>> @@ -238,12 +237,8 @@ static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
>> min_align = PAGES_PER_SUBSECTION;
>> else
>> min_align = PAGES_PER_SECTION;
>> - if (!IS_ALIGNED(pfn, min_align)
>> - || !IS_ALIGNED(nr_pages, min_align)) {
>> - WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
>> - reason, pfn, pfn + nr_pages - 1);
>> + if (!IS_ALIGNED(pfn, min_align) || !IS_ALIGNED(nr_pages, min_align))
>> return -EINVAL;
>> - }
>> return 0;
>> }
>>
>> @@ -320,9 +315,11 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
>> altmap->alloc = 0;
>> }
>>
>> - err = check_pfn_span(pfn, nr_pages, "add");
>> - if (err)
>> + err = check_pfn_span(pfn, nr_pages);
>> + if (err) {
>> + WARN(1, "Misaligned %s start: %#lx end: #%lx\n", __func__, pfn, pfn + nr_pages - 1);
>> return err;
>> + }
>
> If you want to further clean this up, I would just do
>
> if (check_pfn_span()) {
> WARN(....)
> return -EINVAL;
> }
>
> here as we do in __remove_pages(). check_pfn_span() can either return 0 or -EINVAL,
> so I think it is fine.
Sure, will change.
