Re: [PATCH 0/5] remove tlb_remove_page_ptdesc()

[Peter Zijlstra <peterz@infradead.org>]

On Thu, Jan 23, 2025 at 09:26:13PM +0800, Qi Zheng wrote:
> Hi all,
> 
> As suggested by Peter Zijlstra below [1], this series aims to remove
> tlb_remove_page_ptdesc().
> 
> : Fundamentally tlb_remove_page() is about removing *pages* as from a PTE,
> : there should not be a page-table anywhere near here *ever*.
> :
> : Yes, some architectures use tlb_remove_page() for page-tables too, but
> : that is more or less an implementation detail that can be fixed.
> 
> After this series, all architectures use tlb_remove_table() or tlb_remove_ptdesc()
> to remove the page table pages. In the future, once all architectures using
> tlb_remove_table() have also converted to using struct ptdesc (eg. powerpc), it
> may be possible to use only tlb_remove_ptdesc().

Right, so I don't think Sparc and Power care to use ptdesc, they're
using non page page-tables.

At the very least we should do something like this, the only point of
having tlb_remove_ptdesc() is type safety, there really is no benefit
from it in any other way.

---
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index dec030cb1210..a6731328db6f 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -504,7 +504,7 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 	return tlb_remove_page_size(tlb, page, PAGE_SIZE);
 }
 
-static inline void tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
+static inline void tlb_remove_ptdesc(struct mmu_gather *tlb, struct ptdesc *pt)
 {
 	tlb_remove_table(tlb, pt);
 }