* Oleg Nesterov <o...@redhat.com> wrote:
> On 06/11, Ingo Molnar wrote:
> >
> > void sync_global_pgds(unsigned long start, unsigned long end, int removed)
> > {
> > @@ -169,29 +169,33 @@ void sync_global_pgds(unsigned long start, unsigned
> > long end, int removed)
> >
> > for (address = start; address <= end; address += PGDIR_SIZE) {
> > const pgd_t *pgd_ref = pgd_offset_k(address);
> > - struct page *page;
> > + struct task_struct *g, *p;
> >
> > /*
> > - * When it is called after memory hot remove, pgd_none()
> > - * returns true. In this case (removed == 1), we must clear
> > - * the PGD entries in the local PGD level page.
> > + * When this function is called after memory hot remove,
> > + * pgd_none() already returns true, but only the reference
> > + * kernel PGD has been cleared, not the process PGDs.
> > + *
> > + * So clear the affected entries in every process PGD as well:
> > */
> > if (pgd_none(*pgd_ref) && !removed)
> > continue;
> >
> > spin_lock(&pgd_lock);
> > - list_for_each_entry(page, &pgd_list, lru) {
> > - pgd_t *pgd;
> > +
> > + for_each_process_thread(g, p) {
> > + pgd_t *pgd = p->mm->pgd;
>
> and we use the same pgd later: set_pgd(pgd, *pgd_ref).
> looks like this should be pgd_offset(p->mm, address) ?
>
> And obviously you need to check ->mm != NULL first?
Yes.
> And perhaps it makes sense to swap "for (address)" and for_each_process()
> loops...
Yes, but I'd flip around the logic in a later, separate patch.
Note that PGDIR_SIZE is 512 GB here, so the outer loop will most likely execute
at
most twice in practice.
Thanks,
Ingo
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