If we add a migrate_folio operation, we can convert the writepage
operation to writepages. The large folio support here is illusory;
we would need to kmap each page in turn for proper support. But we do
remove a few hidden calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle)
---
fs
Following on from the introduction of P4D-level ctor/dtor, let's
finish the job and introduce ctor/dtor at PGD level. The incurred
improvement in page accounting is minimal - the main motivation is
to create a single, generic place where construction/destruction
hooks can be added for all page tabl
The implementation of pmd_{alloc_one,free} on parisc requires a
non-zero allocation order, but is completely standard aside from
that. Let's reuse the generic implementation of pmd_alloc_one().
Explicit zeroing is not needed as GFP_PGTABLE_KERNEL includes
__GFP_ZERO. The generic pmd_free() can hand
Commit 55d2a0bd5ead ("mm: add statistics for PUD level pagetable")
introduced PUD-level ctor/dtor helpers to improve the accounting of
page table pages. s390 doesn't use the generic pgalloc
implementation and it seems that it got missed in the process. Add
the missing calls to the ctor/dtor helpers
On Thu, Dec 19, 2024 at 04:44:16PM +, Kevin Brodsky wrote:
> Besides the ptlock management at PTE/PMD level, all the
> pagetable_*_[cd]tor have the same implementation. Introduce common
> helpers for all levels to reduce the duplication.
Uff, I forgot to Cc you on the discussion here, sorry!:
On 12/19/24 08:44, Kevin Brodsky wrote:
>
> +---+-+---+--++
> | x86 | Y | Y | Y/N
> | kmem_cache at pgd level if PAE |
>
We already have a generic implementation of alloc/free up to P4D
level, as well as pgd_free(). Let's finish the work and add a
generic PGD-level alloc helper as well.
Unlike at lower levels, almost all architectures need some specific
magic at PGD level (typically initialising PGD entries), so
int
Generic implementations of __pgd_alloc and __pgd_free are about to
be introduced. Rename the macros in arch/arm/mm/pgd.c to avoid
clashes. While we're at it, also pass down the mm as argument to
those helpers, as it will be needed to call the generic
__pgd_{alloc,free}.
Signed-off-by: Kevin Brodsk
Commit 55d2a0bd5ead ("mm: add statistics for PUD level pagetable")
added accounting for PUD-level page tables. This patch does exactly
the same thing for P4D-level page tables, introducing
pagetable_p4d_[cd]tor with the same implementation as the PUD
ctor/dtor and calling them on all alloc/free pat
Four architectures currently implement 5-level pgtables: arm64,
riscv, x86 and s390. The first three have essentially the same
implementation for p4d_alloc_one() and p4d_free(), so we've got an
opportunity to reduce duplication like at the lower levels.
Provide a generic version of p4d_alloc_one()
{pmd,pud,p4d}_alloc_one() is never called if the corresponding page
table level is folded, as {pmd,pud,p4d}_alloc() already does the
required check. We can therefore remove the runtime page table level
checks in {pud,p4d}_alloc_one. The PUD helper becomes equivalent to
the generic version, so we re
get_pointer_table() and free_pointer_table() already special-case
TABLE_PTE to call pagetable_pte_[cd]tor. Let's do the same at PMD
level to improve accounting further. TABLE_PGD and TABLE_PMD are
currently defined to the same value, so we first need to separate
them. That also implies separating p
Besides the ptlock management at PTE/PMD level, all the
pagetable_*_[cd]tor have the same implementation. Introduce common
helpers for all levels to reduce the duplication.
Signed-off-by: Kevin Brodsky
---
include/linux/mm.h | 46 ++
1 file changed, 22
We currently have a pair of ctor/dtor calls for lower page table levels,
up to PUD. At PTE and PMD level, these handle split locks,
if supported. Additionally, the helpers ensure correct accounting of
page table pages to the corresponding process.
This series takes that principle to its logical co
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