lkml.org 
[lkml]   [2015]   [Sep]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] x86: fix small LDT allocation for Xen

* Jan Beulich <JBeulich@suse.com> wrote:

> >> @@ -95,7 +95,7 @@ static void free_ldt_struct(struct ldt_s
> >> if (ldt->size * LDT_ENTRY_SIZE > PAGE_SIZE)
> >> vfree(ldt->entries);
> >> else
> >> - kfree(ldt->entries);
> >> + put_page(virt_to_page(ldt->entries));
> >
> > FWIW, I'm not convinced this is or was correct. Using free_page looks
> > a bit safer, and free_page does more than just put_page.
>
> Actually I agree. put_page() is meant to be paired with get_page();
> __get_free_pages() is just misleading (i.e. doesn't imply a get_page())
> and instead is to be paired with free_pages(). Will do a v3 then.

So put_page() is a page cache primitive and should not be used outside of it.

As it happens, it is safe to put_page() a regularly allocated page as well, but
it's a little bit slower than doing a free_page().

Thanks,

Ingo


\
 
 \ /
  Last update: 2015-09-02 19:21    [W:0.291 / U:0.532 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site