Hi Mike,
On 2024/2/4 18:58, Mike Rapoport wrote:
On Thu, Feb 01, 2024 at 04:05:40PM +0800, Qi Zheng wrote:
For kernel PTE page, we do not need to allocate and initialize its split
ptlock, but as a page table page, it's still necessary to add PG_table
flag and NR_PAGETABLE statistics for it.
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
---
include/asm-generic/pgalloc.h | 7 ++++++-
include/linux/mm.h | 21 ++++++++++++++++-----
2 files changed, 22 insertions(+), 6 deletions(-)
This should also update the architectures that define
__HAVE_ARCH_PTE_ALLOC_ONE_KERNEL, otherwise NR_PAGETABLE counts will get
wrong.
Yes, this patchset only focuses on the generic implementation. For those
architectures that define __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL, some reuse
the generic __pte_alloc_one_kernel(), but some have their own customized
implementations, which indeed need to be fixed.
I wasn't familiar with those architectures and didn't investigate why
they couldn't reuse the generic __pte_alloc_one_kernel(), so I didn't
fix them. It would be better if there are maintainers corresponding to
the architecture who can help fix it. After all, they have a better
understanding of the historical background and have a testing
environment. ;)
Another related thing is that many architectures have custom allocations
for early page tables and these would also benefit form NR_PAGETABLE
accounting.
Indeed, this is also a point that can be optimized.
Thanks.
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 879e5f8aa5e9..908bd9140ac2 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -23,6 +23,8 @@ static inline pte_t *__pte_alloc_one_kernel(struct mm_struct *mm)
if (!ptdesc)
return NULL;
+
+ __pagetable_pte_ctor(ptdesc);
return ptdesc_address(ptdesc);
}
@@ -46,7 +48,10 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
*/
static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
{
- pagetable_free(virt_to_ptdesc(pte));
+ struct ptdesc *ptdesc = virt_to_ptdesc(pte);
+
+ __pagetable_pte_dtor(ptdesc);
+ pagetable_free(ptdesc);
}
/**
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e442fd0efdd9..e37db032764e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2922,26 +2922,37 @@ static inline bool ptlock_init(struct ptdesc *ptdesc) { return true; }
static inline void ptlock_free(struct ptdesc *ptdesc) {}
#endif /* USE_SPLIT_PTE_PTLOCKS */
-static inline bool pagetable_pte_ctor(struct ptdesc *ptdesc)
+static inline void __pagetable_pte_ctor(struct ptdesc *ptdesc)
{
struct folio *folio = ptdesc_folio(ptdesc);
- if (!ptlock_init(ptdesc))
- return false;
__folio_set_pgtable(folio);
lruvec_stat_add_folio(folio, NR_PAGETABLE);
+}
+
+static inline bool pagetable_pte_ctor(struct ptdesc *ptdesc)
+{
+ if (!ptlock_init(ptdesc))
+ return false;
+
+ __pagetable_pte_ctor(ptdesc);
return true;
}
-static inline void pagetable_pte_dtor(struct ptdesc *ptdesc)
+static inline void __pagetable_pte_dtor(struct ptdesc *ptdesc)
{
struct folio *folio = ptdesc_folio(ptdesc);
- ptlock_free(ptdesc);
__folio_clear_pgtable(folio);
lruvec_stat_sub_folio(folio, NR_PAGETABLE);
}
+static inline void pagetable_pte_dtor(struct ptdesc *ptdesc)
+{
+ ptlock_free(ptdesc);
+ __pagetable_pte_dtor(ptdesc);
+}
+
pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp);
static inline pte_t *pte_offset_map(pmd_t *pmd, unsigned long addr)
{
--
2.30.2
