On Mon, Mar 06, 2023 at 08:51:45PM +0530, Ritesh Harjani wrote:
> Matthew Wilcox <willy@xxxxxxxxxxxxx> writes:
>
> > On Mon, Mar 06, 2023 at 12:21:48PM +0530, Ritesh Harjani wrote:
> >> "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> writes:
> >>
> >> > All the callers now have a folio, so pass that in and operate on folios.
> >> > Removes four calls to compound_head().
> >>
> >> Why do you say four? Isn't it 3 calls of PageUptodate(page) which
> >> removes calls to compound_head()? Which one did I miss?
> >>
> >> > - BUG_ON(!PageLocked(page));
> >> > + BUG_ON(!folio_test_locked(folio));
> >
> > That one ;-)
>
> __PAGEFLAG(Locked, locked, PF_NO_TAIL)
>
> #define __PAGEFLAG(uname, lname, policy) \
> TESTPAGEFLAG(uname, lname, policy) \
> __SETPAGEFLAG(uname, lname, policy) \
> __CLEARPAGEFLAG(uname, lname, policy)
>
> #define TESTPAGEFLAG(uname, lname, policy) \
> static __always_inline bool folio_test_##lname(struct folio *folio) \
> { return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
> static __always_inline int Page##uname(struct page *page) \
> { return test_bit(PG_##lname, &policy(page, 0)->flags); }
>
> How? PageLocked(page) doesn't do any compount_head() calls no?
You missed one piece of the definition ...
#define PF_NO_TAIL(page, enforce) ({ \
VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
PF_POISONED_CHECK(compound_head(page)); })
