On 7/3/2022 10:28 PM, Mike Rapoport wrote:
On Sun, Jul 03, 2022 at 10:06:32PM +0800, Baolin Wang wrote:
On 7/3/2022 11:40 AM, Matthew Wilcox wrote:
On Fri, Jul 01, 2022 at 04:04:21PM +0800, Baolin Wang wrote:
Using pgtable_pud_page_ctor() and pgtable_pud_page_dtor() would be
consistent with what we currently have for PTEs and PMDs.
This applies to all the additions of pgtable_page_dec() and
pgtable_page_inc().
OK. I can add pgtable_pud_page_ctor() and pgtable_pud_page_dtor() helpers to
keep consistent, which are just wrappers of pgtable_page_inc() and
pgtable_page_dec().
I think you misunderstand Mike.
Don't add pgtable_page_inc() and pgtable_page_dec(). Just add
pgtable_pud_page_ctor() and pgtable_pud_page_dtor(). At least, that
was what I said last time you posted these patches.
My concern is that I need another helpers for kernel page table allocation
helpers, if only adding pgtable_pud_page_ctor() and pgtable_pud_page_dtor()
like below:
static inline void pgtable_pud_page_ctor(struct page *page)
{
__SetPageTable(page);
inc_lruvec_page_state(page, NR_PAGETABLE);
}
static inline void pgtable_pud_page_dtor(struct page *page)
{
__ClearPageTable(page);
dec_lruvec_page_state(page, NR_PAGETABLE);
}
So for kernel pte page table allocation, I need another similar helpers like
below. However they do the samething with
pgtable_pud_page_ctor/pgtable_pud_page_dtor, so I am not sure this is good
for adding these duplicate code.
static inline void pgtable_kernel_pte_page_ctor(struct page *page)
{
__SetPageTable(page);
inc_lruvec_page_state(page, NR_PAGETABLE);
}
static inline void pgtable_kernel_pte_page_dtor(struct page *page)
{
__ClearPageTable(page);
dec_lruvec_page_state(page, NR_PAGETABLE);
}
Instead adding a common helpers seems more readable to me, which can also
simplify original pgtable_pmd_page_dtor()/pgtable_pmd_page_ctor(). Something
like below.
static inline void pgtable_page_inc(struct page *page)
{
__SetPageTable(page);
inc_lruvec_page_state(page, NR_PAGETABLE);
}
static inline void pgtable_page_dec(struct page *page)
{
__ClearPageTable(page);
dec_lruvec_page_state(page, NR_PAGETABLE);
}
static inline void pgtable_pud_page_ctor(struct page *page)
{
pgtable_page_inc(page);
}
static inline void pgtable_pud_page_dtor(struct page *page)
{
pgtable_page_dec(page);
}
For kernel pte page table, we can just use
pgtable_page_inc/pgtable_page_dec(), or adding
pgtable_kernel_pte_page_ctor/pgtable_kernel_pte_page_dtor, which just
wrappers of pgtable_page_inc() and pgtable_page_dec().
Matthew and Mike, how do you think? Thanks.
I actually meant to add pgtable_pud_page_ctor/dtor() as a wrapper for the
new helper to keep pud tables allocation consistent with pmd and pte and
as a provision for the time we'll have per-page pud locks.
For the accounting of the kernel page tables a new helper does make sense
because there are no locks to initialize for the kernel page tables.
Thanks for clarification. That is also my thought.
I can't say that I'm happy with the pgtable_page_inc/dec names, though.
Maybe page_{set,clear}_pgtable()?
Sounds better than pgtable_page_inc/dec() for me. I will use them in
next version if no other objections. Thanks.
