On Wed, Jan 31, 2018 at 07:09:48PM +0200, Igor Stoppa wrote: > On 30/01/18 02:43, Jerome Glisse wrote: > > [...] > > > Maybe we can kill page->mapping altogether as a result of this. However this is > > not my motivation at this time. > > We had a discussion some time ago > > http://www.openwall.com/lists/kernel-hardening/2017/07/07/7 > > where you advised to use it for tracking pmalloc pages vs area, which > generated this patch: > > http://www.openwall.com/lists/kernel-hardening/2018/01/24/7 > > Could you please comment what wold happen to the shortcut from struct > page to vm_struct that this patch is now introducing? Sadly struct page fields means different thing depending on the context in which the page is use. This is confusing i know. So when i say kill page->mapping i am not saying shrink the struct page and remove that field, i am saying maybe we can kill current user of page->mapping for regular process page (ie page that are in some mmap() area of a process). Other use of that field in different context like yours are not affected by this change and can ignore it alltogether. Hope this clarify it :) Cheers, Jérôme
