On Wed, Oct 6, 2021 at 3:02 PM Peter Xu <peterx@xxxxxxxxxx> wrote:
>
> On Thu, Sep 30, 2021 at 02:53:09PM -0700, Yang Shi wrote:
> > +/*
> > + * Return true if page is still referenced by others, otherwise return
> > + * false.
> > + *
> > + * The dec is true when one extra refcount is expected.
> > + */
> > +static bool has_extra_refcount(struct page_state *ps, struct page *p,
> > + bool dec)
>
> Nit: would it be nicer to keep using things like "extra_pins", so we pass in 1
> for swapcache dirty case and 0 for the rest? Then it'll also match with most
> of the similar cases in e.g. huge_memory.c (please try grep "extra_pins" there).
Thanks for the suggestion. Yes, it makes some sense to me. And the
code comments in patch 4/5 does says (the suggested version by Naoya):
/*
* The shmem page is kept in page cache instead of truncating
* so is expected to have an extra refcount after error-handling.
*/
Will rename it in the new version.
>
> > +{
> > + int count = page_count(p) - 1;
> > +
> > + if (dec)
> > + count -= 1;
> > +
> > + if (count > 0) {
> > + pr_err("Memory failure: %#lx: %s still referenced by %d users\n",
> > + page_to_pfn(p), action_page_types[ps->type], count);
> > + return true;
> > + }
> > +
> > + return false;
> > +}
> > +
> > /*
> > * Error hit kernel page.
> > * Do nothing, try to be lucky and not touch this instead. For a few cases we
> > * could be more sophisticated.
> > */
> > -static int me_kernel(struct page *p, unsigned long pfn)
> > +static int me_kernel(struct page_state *ps, struct page *p)
>
> Not sure whether it's intended, but some of the action() hooks do not call the
> refcount check now while in the past they'll all do. Just to double check
> they're expected, like this one and me_unknown().
Yeah, it is intentional. Before this change all me_* handlers did
check refcount even though it was not necessary, for example,
me_kernel() and me_unknown().
>
> > {
> > unlock_page(p);
> > return MF_IGNORED;
> > @@ -820,9 +852,9 @@ static int me_kernel(struct page *p, unsigned long pfn)
> > /*
> > * Page in unknown state. Do nothing.
> > */
> > -static int me_unknown(struct page *p, unsigned long pfn)
> > +static int me_unknown(struct page_state *ps, struct page *p)
> > {
> > - pr_err("Memory failure: %#lx: Unknown page state\n", pfn);
> > + pr_err("Memory failure: %#lx: Unknown page state\n", page_to_pfn(p));
> > unlock_page(p);
> > return MF_FAILED;
> > }
>
> Thanks,
>
> --
> Peter Xu
>
