mm: pgtable: make generic tlb_remove_table() use struct ptdesc

Patch series "remove tlb_remove_page_ptdesc()", v2.

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().

[1] https://lore.kernel.org/linux-mm/[email protected]/


This patch (of 6):

Now only arm will call tlb_remove_ptdesc()/tlb_remove_table() when
CONFIG_MMU_GATHER_TABLE_FREE is disabled.  In this case, the type of the
table parameter is actually struct ptdesc * instead of struct page *.

Since struct ptdesc still overlaps with struct page and has not been
separated from it, forcing the table parameter to struct page * will not
cause any problems at this time.  But this is definitely incorrect and
needs to be fixed.  So just like the generic __tlb_remove_table(), let
generic tlb_remove_table() use struct ptdesc by default when
CONFIG_MMU_GATHER_TABLE_FREE is disabled.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/5be8c3ab7bd68510bf0db4cf84010f4dfe372917.1740454179.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Kevin Brodsky <[email protected]>
Cc: Alexandre Ghiti <[email protected]>
Cc: "Aneesh Kumar K.V" <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Hugh Dickens <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Matthew Wilcow (Oracle) <[email protected]>
Cc: "Mike Rapoport (IBM)" <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Yu Zhao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Qi Zheng

include/asm-generic/tlb.h

@@ -227,10 +227,10 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page);
  */
 static inline void tlb_remove_table(struct mmu_gather *tlb, void *table)
 {
-	struct page *page = (struct page *)table;
+	struct ptdesc *ptdesc = (struct ptdesc *)table;
 
-	pagetable_dtor(page_ptdesc(page));
-	tlb_remove_page(tlb, page);
+	pagetable_dtor(ptdesc);
+	tlb_remove_page(tlb, ptdesc_page(ptdesc));
 }
 #endif /* CONFIG_MMU_GATHER_TABLE_FREE */