On Wednesday, 22 August 2007 10:29, Pavel Machek wrote:
> Hi!
>
> > Use temporary page tables for the kernel text mapping during hibernation
> > restore
> > on x86_64.
> >
> > Without the patch, the original boot kernel's page tables that represent the
> > kernel text mapping are used while the core of the image kernel is being
> > restored. However, in principle, if the boot kernel is not identical to the
> > image kernel, the location of these page tables in the image kernel need
> > not be
> > the same, so we should create a safe copy of the kernel text mapping prior
> > to
> > restoring the core of the image kernel.
>
>
> > @@ -190,25 +190,42 @@ static int res_phys_pud_init(pud_t *pud,
> > return 0;
> > }
> >
> > +static int res_kernel_text_pud_init(pud_t *pud, unsigned long start)
> > +{
> > + pmd_t *pmd;
> > + unsigned long paddr;
> > +
> > + pmd = (pmd_t *)get_safe_page(GFP_ATOMIC);
> > + if (!pmd)
> > + return -ENOMEM;
> > + set_pud(pud + pud_index(start), __pud(__pa(pmd) | _KERNPG_TABLE));
> > + for (paddr = 0; paddr < KERNEL_TEXT_SIZE; pmd++, paddr += PMD_SIZE) {
> > + unsigned long pe;
> > +
> > + pe = __PAGE_KERNEL_LARGE_EXEC | _PAGE_GLOBAL | paddr;
> > + pe &= __supported_pte_mask;
> > + set_pmd(pmd, __pmd(pe));
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static int set_up_temporary_mappings(void)
> > {
> > unsigned long start, end, next;
> > + pud_t *pud;
> > int error;
> >
> > temp_level4_pgt = (pgd_t *)get_safe_page(GFP_ATOMIC);
> > if (!temp_level4_pgt)
> > return -ENOMEM;
> >
> > - /* It is safe to reuse the original kernel mapping */
> > - set_pgd(temp_level4_pgt + pgd_index(__START_KERNEL_map),
> > - init_level4_pgt[pgd_index(__START_KERNEL_map)]);
> > -
> > /* Set up the direct mapping from scratch */
> > start = (unsigned long)pfn_to_kaddr(0);
> > end = (unsigned long)pfn_to_kaddr(end_pfn);
> >
> > for (; start < end; start = next) {
> > - pud_t *pud = (pud_t *)get_safe_page(GFP_ATOMIC);
> > + pud = (pud_t *)get_safe_page(GFP_ATOMIC);
> > if (!pud)
> > return -ENOMEM;
>
> I believe we leak temp_level4_pgt here.
>
> > + /* Set up the kernel text mapping from scratch */
> > + pud = (pud_t *)get_safe_page(GFP_ATOMIC);
> > + if (!pud)
> > + return -ENOMEM;
>
> ...and some more memory here :-(.
No, these pages will be freed by swsusp_free(), thanks to the get_safe_page().
I'm not _that_ careless. ;-)
Greetings,
Rafael
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