[PATCH v2 0/4] bugfix: Introduce sendpages_ok() to check sendpage_ok() on contiguous pages

[Hannes Reinecke]

On 6/2/24 00:34, Jakub Kicinski wrote:
> On Thu, 30 May 2024 17:24:10 +0300 Ofir Gal wrote:
>> skbuff: before sendpage_ok - i: 0. page: 0x654eccd7 (pfn: 120755)
>> skbuff: before sendpage_ok - i: 1. page: 0x1666a4da (pfn: 120756)
>> skbuff: before sendpage_ok - i: 2. page: 0x54f9f140 (pfn: 120757)
> 
> noob question, how do you get 3 contiguous pages, the third of which
> is slab? is_slab doesn't mean what I think it does, or we got extremely
> lucky with kmalloc?
> 
I guess it's not slab which triggered; the actual code is:

static inline bool sendpage_ok(struct page *page)
{
         return !PageSlab(page) && page_count(page) >= 1;
}

My bet is on 'page_count()' triggering.

Cheers,

Hannes