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mm/rmap: introduce and use hugetlb_add_file_rmap()

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hugetlb rmap handling differs quite a lot from "ordinary" rmap code.  For
example, hugetlb currently only supports entire mappings, and treats any
mapping as mapped using a single "logical PTE".  Let's move it out of the
way so we can overhaul our "ordinary" rmap.  implementation/interface.

Right now we're using page_dup_file_rmap() in some cases where "ordinary"
rmap code would have used page_add_file_rmap().  So let's introduce and
use hugetlb_add_file_rmap() instead.  We won't be adding a
"hugetlb_dup_file_rmap()" functon for the fork() case, as it would be
doing the same: "dup" is just an optimization for "add".

What remains is a single page_dup_file_rmap() call in fork() code.

Add sanity checks that we end up with the right folios in the right
functions.

Link: https://lkml.kernel.org/r/20231220224504.646757-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2023-12-20 23:44:27 +01:00 committed by Andrew Morton
parent e135826b2d
commit 44887f3994
4 changed files with 13 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/linux/rmap.h
View File

@ -211,6 +211,14 @@ void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *,
void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
unsigned long address);
static inline void hugetlb_add_file_rmap(struct folio *folio)
{
VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
atomic_inc(&folio->_entire_mapcount);
}
static inline void hugetlb_remove_rmap(struct folio *folio)
{
VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);

6
mm/hugetlb.c
View File

@ -5408,7 +5408,7 @@ again:
* sleep during the process.
*/
if (!folio_test_anon(pte_folio)) {
page_dup_file_rmap(&pte_folio->page, true);
hugetlb_add_file_rmap(pte_folio);
} else if (page_try_dup_anon_rmap(&pte_folio->page,
true, src_vma)) {
pte_t src_pte_old = entry;
@ -6279,7 +6279,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
if (anon_rmap)
hugetlb_add_new_anon_rmap(folio, vma, haddr);
else
page_dup_file_rmap(&folio->page, true);
hugetlb_add_file_rmap(folio);
new_pte = make_huge_pte(vma, &folio->page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
/*
@ -6730,7 +6730,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
goto out_release_unlock;
if (folio_in_pagecache)
page_dup_file_rmap(&folio->page, true);
hugetlb_add_file_rmap(folio);
else
hugetlb_add_new_anon_rmap(folio, dst_vma, dst_addr);

2
mm/migrate.c
View File

@ -252,7 +252,7 @@ static bool remove_migration_pte(struct folio *folio,
hugetlb_add_anon_rmap(folio, vma, pvmw.address,
rmap_flags);
else
page_dup_file_rmap(new, true);
hugetlb_add_file_rmap(folio);
set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte,
psize);
} else

1
mm/rmap.c
View File

@ -1395,6 +1395,7 @@ void folio_add_file_rmap_range(struct folio *folio, struct page *page,
unsigned int nr_pmdmapped = 0, first;
int nr = 0;
VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
/* Is page being mapped by PTE? Is this its first map to be added? */