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Message-ID: <07e0c05f-cb69-4263-885d-6d20d4442152@bytedance.com>
Date: Tue, 7 Jan 2025 18:51:07 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Kevin Brodsky <kevin.brodsky@....com>
Cc: 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, 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,
peterz@...radead.org, akpm@...ux-foundation.org
Subject: Re: [PATCH v4 10/15] riscv: pgtable: move pagetable_dtor() to
__tlb_remove_table()
On 2025/1/7 17:57, Kevin Brodsky wrote:
> On 06/01/2025 04:49, Qi Zheng wrote:
>> [...]
>>
>>> Once this is done, we should be able to replace all those confusing
>>> calls to tlb_remove_page() on PTPs with tlb_remove_table() and remove
>>> the explicit call to pagetable_dtor(). AIUI this is essentially what
>>> Peter suggested on v3 [2].
>>
>> Since this patch series is mainly for bug fix, I think that these things
>> can be done in separate patch series later.
>
> Sure that's fair.
>
>>
>>>
>>> [...]
>>>
>>>> Or can we just not let tlb_remove_table() fall back to
>>>> tlb_remove_page()? Like the following:
>>>>
>>>> diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
>>>> index a59205863f431..354ffaa4bd120 100644
>>>> --- a/include/asm-generic/tlb.h
>>>> +++ b/include/asm-generic/tlb.h
>>>> @@ -195,8 +195,6 @@
>>>> * various ptep_get_and_clear() functions.
>>>> */
>>>>
>>>> -#ifdef CONFIG_MMU_GATHER_TABLE_FREE
>>>> -
>>>> struct mmu_table_batch {
>>>> #ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE
>>>> struct rcu_head rcu;
>>>> @@ -219,16 +217,6 @@ static inline void __tlb_remove_table(void *table)
>>>>
>>>> extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
>>>>
>>>> -#else /* !CONFIG_MMU_GATHER_HAVE_TABLE_FREE */
>>>> -
>>>> -/*
>>>> - * Without MMU_GATHER_TABLE_FREE the architecture is assumed to have
>>>> page based
>>>> - * page directories and we can use the normal page batching to free
>>>> them.
>>>> - */
>>>> -#define tlb_remove_table(tlb, page) tlb_remove_page((tlb), (page))
>>>
>>> We still need a different implementation of tlb_remove_table() in this
>>> case. We could define it inline here:
>>>
>>> static inline void tlb_remove_table(struct mmu_gather *tlb, void *table)
>>> {
>>> struct page *page = table;
>>>
>>> pagetable_dtor(page_ptdesc(page));
>>> tlb_remove_page(page);
>>> }
>>
>> Right. As I said above, will add this to the updated patch #8.
>
> I think it would be preferable to make it a standalone patch, because
> this is a change to generic code that could in principle impact other
> arch's too.
Agree, I have done that:
```
Author: Qi Zheng <zhengqi.arch@...edance.com>
Date: Fri Dec 13 17:13:48 2024 +0800
mm: pgtable: completely move pagetable_dtor() to generic
tlb_remove_table()
For the generic tlb_remove_table(), it is implemented in the
following two
forms:
1) CONFIG_MMU_GATHER_TABLE_FREE is enabled
tlb_remove_table
--> generic __tlb_remove_table()
2) CONFIG_MMU_GATHER_TABLE_FREE is disabled
tlb_remove_table
--> tlb_remove_page
For case 1), the pagetable_dtor() has already been moved to generic
__tlb_remove_table().
For case 2), now only arm will call
tlb_remove_table()/tlb_remove_ptdesc()
when CONFIG_MMU_GATHER_TABLE_FREE is disabled. Let's move
pagetable_dtor()
completely to generic tlb_remove_table(), so that the architectures can
follow more easily.
Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
diff --git a/arch/arm/include/asm/tlb.h b/arch/arm/include/asm/tlb.h
index b8eebdb598631..ea4fbe7b17f6f 100644
--- a/arch/arm/include/asm/tlb.h
+++ b/arch/arm/include/asm/tlb.h
@@ -34,10 +34,6 @@ __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
unsigned long addr)
{
struct ptdesc *ptdesc = page_ptdesc(pte);
-#ifndef CONFIG_MMU_GATHER_TABLE_FREE
- pagetable_dtor(ptdesc);
-#endif
-
#ifndef CONFIG_ARM_LPAE
/*
* With the classic ARM MMU, a pte page has two corresponding pmd
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 69de47c7ef3c5..53ae7748f555b 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -220,14 +220,20 @@ static inline void __tlb_remove_table(void *table)
extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
-#else /* !CONFIG_MMU_GATHER_HAVE_TABLE_FREE */
+#else /* !CONFIG_MMU_GATHER_TABLE_FREE */
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page
*page);
/*
* Without MMU_GATHER_TABLE_FREE the architecture is assumed to have
page based
* page directories and we can use the normal page batching to free them.
*/
-#define tlb_remove_table(tlb, page) tlb_remove_page((tlb), (page))
+static inline void tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+ struct page *page = (struct page *)table;
+ pagetable_dtor(page_ptdesc(page));
+ tlb_remove_page(tlb, page);
+}
#endif /* CONFIG_MMU_GATHER_TABLE_FREE */
#ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE
```
and will send v5 later.
Thanks!
>
> - Kevin
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