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Message-ID: <ebce5e05-5e46-4c6e-94a0-bcf3655a862b@bytedance.com>
Date: Fri, 3 Jan 2025 11:48:27 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Kevin Brodsky <kevin.brodsky@....com>
Cc: peterz@...radead.org, agordeev@...ux.ibm.com, palmer@...belt.com,
tglx@...utronix.de, david@...hat.com, jannh@...gle.com, hughd@...gle.com,
yuzhao@...gle.com, willy@...radead.org, muchun.song@...ux.dev,
vbabka@...nel.org, lorenzo.stoakes@...cle.com, akpm@...ux-foundation.org,
rientjes@...gle.com, vishal.moola@...il.com, arnd@...db.de, will@...nel.org,
aneesh.kumar@...nel.org, npiggin@...il.com, dave.hansen@...ux.intel.com,
rppt@...nel.org, ryan.roberts@....com, linux-mm@...ck.org,
linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
linux-arch@...r.kernel.org, linux-csky@...r.kernel.org,
linux-hexagon@...r.kernel.org, loongarch@...ts.linux.dev,
linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
linux-openrisc@...r.kernel.org, linux-sh@...r.kernel.org,
linux-um@...ts.infradead.org
Subject: Re: [PATCH v4 10/15] riscv: pgtable: move pagetable_dtor() to
__tlb_remove_table()
Hi Kevin,
On 2025/1/3 00:53, Kevin Brodsky wrote:
> On 30/12/2024 10:07, Qi Zheng wrote:
>> static inline void riscv_tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
>> {
>> - if (riscv_use_sbi_for_rfence())
>> + if (riscv_use_sbi_for_rfence()) {
>> tlb_remove_ptdesc(tlb, pt);
>> - else
>> + } else {
>> + pagetable_dtor(pt);
>> tlb_remove_page_ptdesc(tlb, pt);
>
> I find the imbalance pretty confusing: pagetable_dtor() is called
> explicitly before using tlb_remove_page() but not tlb_remove_ptdesc().
> Doesn't that assume that CONFIG_MMU_GATHER_HAVE_TABLE_FREE is selected?
> Could we not call pagetable_dtor() from __tlb_batch_free_encoded_pages()
> to ensure that the dtor is always called just before freeing, and remove
In __tlb_batch_free_encoded_pages(), we can indeed detect PageTable()
and call pagetable_dtor() to dtor the page table pages.
But __tlb_batch_free_encoded_pages() is also used to free normal pages
(not page table pages), so I don't want to add overhead there.
But now I think maybe we can do this in tlb_remove_page_ptdesc(), like
this:
diff --git a/arch/csky/include/asm/pgalloc.h
b/arch/csky/include/asm/pgalloc.h
index f1ce5b7b28f22..e45c7e91dcbf9 100644
--- a/arch/csky/include/asm/pgalloc.h
+++ b/arch/csky/include/asm/pgalloc.h
@@ -63,7 +63,6 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
#define __pte_free_tlb(tlb, pte, address) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc(tlb, page_ptdesc(pte)); \
} while (0)
diff --git a/arch/hexagon/include/asm/pgalloc.h
b/arch/hexagon/include/asm/pgalloc.h
index 40e42a0e71673..9903449f45cff 100644
--- a/arch/hexagon/include/asm/pgalloc.h
+++ b/arch/hexagon/include/asm/pgalloc.h
@@ -89,7 +89,6 @@ static inline void pmd_populate_kernel(struct
mm_struct *mm, pmd_t *pmd,
#define __pte_free_tlb(tlb, pte, addr) \
do { \
- pagetable_dtor((page_ptdesc(pte))); \
tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte))); \
} while (0)
diff --git a/arch/loongarch/include/asm/pgalloc.h
b/arch/loongarch/include/asm/pgalloc.h
index 7211dff8c969e..de5b3f5c85d1c 100644
--- a/arch/loongarch/include/asm/pgalloc.h
+++ b/arch/loongarch/include/asm/pgalloc.h
@@ -57,7 +57,6 @@ static inline pte_t *pte_alloc_one_kernel(struct
mm_struct *mm)
#define __pte_free_tlb(tlb, pte, address) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc((tlb), page_ptdesc(pte)); \
} while (0)
diff --git a/arch/m68k/include/asm/sun3_pgalloc.h
b/arch/m68k/include/asm/sun3_pgalloc.h
index 2b626cb3ad0ae..731cc8f0731d3 100644
--- a/arch/m68k/include/asm/sun3_pgalloc.h
+++ b/arch/m68k/include/asm/sun3_pgalloc.h
@@ -19,7 +19,6 @@ extern const char bad_pmd_string[];
#define __pte_free_tlb(tlb, pte, addr) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc((tlb), page_ptdesc(pte)); \
} while (0)
diff --git a/arch/mips/include/asm/pgalloc.h
b/arch/mips/include/asm/pgalloc.h
index 36d9805033c4b..964ad514be281 100644
--- a/arch/mips/include/asm/pgalloc.h
+++ b/arch/mips/include/asm/pgalloc.h
@@ -56,7 +56,6 @@ static inline void pgd_free(struct mm_struct *mm,
pgd_t *pgd)
#define __pte_free_tlb(tlb, pte, address) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc((tlb), page_ptdesc(pte)); \
} while (0)
diff --git a/arch/nios2/include/asm/pgalloc.h
b/arch/nios2/include/asm/pgalloc.h
index 12a536b7bfbd4..ef6b4b8301ac6 100644
--- a/arch/nios2/include/asm/pgalloc.h
+++ b/arch/nios2/include/asm/pgalloc.h
@@ -30,7 +30,6 @@ extern pgd_t *pgd_alloc(struct mm_struct *mm);
#define __pte_free_tlb(tlb, pte, addr) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte))); \
} while (0)
diff --git a/arch/openrisc/include/asm/pgalloc.h
b/arch/openrisc/include/asm/pgalloc.h
index 596e2355824e3..9361205610910 100644
--- a/arch/openrisc/include/asm/pgalloc.h
+++ b/arch/openrisc/include/asm/pgalloc.h
@@ -68,7 +68,6 @@ extern pte_t *pte_alloc_one_kernel(struct mm_struct *mm);
#define __pte_free_tlb(tlb, pte, addr) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte))); \
} while (0)
diff --git a/arch/riscv/include/asm/pgalloc.h
b/arch/riscv/include/asm/pgalloc.h
index c8907b8317115..61c26576614da 100644
--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -25,12 +25,10 @@
*/
static inline void riscv_tlb_remove_ptdesc(struct mmu_gather *tlb,
void *pt)
{
- if (riscv_use_sbi_for_rfence()) {
+ if (riscv_use_sbi_for_rfence())
tlb_remove_ptdesc(tlb, pt);
- } else {
- pagetable_dtor(pt);
+ else
tlb_remove_page_ptdesc(tlb, pt);
- }
}
static inline void pmd_populate_kernel(struct mm_struct *mm,
diff --git a/arch/sh/include/asm/pgalloc.h b/arch/sh/include/asm/pgalloc.h
index 96d938fdf2244..5b5c73e9fdb4b 100644
--- a/arch/sh/include/asm/pgalloc.h
+++ b/arch/sh/include/asm/pgalloc.h
@@ -34,7 +34,6 @@ static inline void pmd_populate(struct mm_struct *mm,
pmd_t *pmd,
#define __pte_free_tlb(tlb, pte, addr) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte))); \
} while (0)
diff --git a/arch/um/include/asm/pgalloc.h b/arch/um/include/asm/pgalloc.h
index f0af23c3aeb2b..4fd59fb184818 100644
--- a/arch/um/include/asm/pgalloc.h
+++ b/arch/um/include/asm/pgalloc.h
@@ -27,7 +27,6 @@ extern pgd_t *pgd_alloc(struct mm_struct *);
#define __pte_free_tlb(tlb, pte, address) \
do { \
- pagetable_dtor(page_ptdesc(pte)); \
tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte))); \
} while (0)
@@ -35,7 +34,6 @@ do {
\
#define __pmd_free_tlb(tlb, pmd, address) \
do { \
- pagetable_dtor(virt_to_ptdesc(pmd)); \
tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pmd)); \
} while (0)
@@ -43,7 +41,6 @@ do {
\
#define __pud_free_tlb(tlb, pud, address) \
do { \
- pagetable_dtor(virt_to_ptdesc(pud)); \
tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pud)); \
} while (0)
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index a96d4b440f3da..a59205863f431 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -506,6 +506,7 @@ static inline void tlb_remove_ptdesc(struct
mmu_gather *tlb, void *pt)
/* Like tlb_remove_ptdesc, but for page-like page directories. */
static inline void tlb_remove_page_ptdesc(struct mmu_gather *tlb,
struct ptdesc *pt)
{
+ pagetable_dtor(pt);
tlb_remove_page(tlb, ptdesc_page(pt));
}
This avoids explicitly calling pagetable_dtor() in the architecture
code. If that makes sense, I can send a formal separate patch to do
this.
Thanks,
Qi
> the extra handling from arch code? I may well be missing something, I'm
> not super familiar with the tlb handling code >
> - Kevin
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