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mm: rmap: simplify the hugetlb handling when unmapping or migration

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According to previous discussion [1], there are so many levels of
indenting to handle the hugetlb case when unmapping or migration.  We can
combine folio_test_anon() and huge_pmd_unshare() to save one level of
indenting, by adding a local variable and moving the VM_BUG_ON() a little
forward.

No intended functional changes in this patch.

[1] https://lore.kernel.org/all/0b986dc4-5843-3e2d-c2df-5a2e9f13e6ab@oracle.com/

Link: https://lkml.kernel.org/r/28414b1b96f095e838c1e548074f8e0fc70d78cf.1655724713.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baolin Wang 2022-06-20 19:47:15 +08:00 committed by akpm
parent f7cc67ae7f
commit 0506c31d0a
1 changed files with 44 additions and 46 deletions
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18
mm/rmap.c
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@ -1537,6 +1537,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
PageAnonExclusive(subpage); PageAnonExclusive(subpage);
if (folio_test_hugetlb(folio)) { if (folio_test_hugetlb(folio)) {
bool anon = folio_test_anon(folio);
/* /*
* The try_to_unmap() is only passed a hugetlb page * The try_to_unmap() is only passed a hugetlb page
* in the case where the hugetlb page is poisoned. * in the case where the hugetlb page is poisoned.
@ -1551,15 +1553,13 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
*/ */
flush_cache_range(vma, range.start, range.end); flush_cache_range(vma, range.start, range.end);
if (!folio_test_anon(folio)) {
/* /*
* To call huge_pmd_unshare, i_mmap_rwsem must be * To call huge_pmd_unshare, i_mmap_rwsem must be
* held in write mode. Caller needs to explicitly * held in write mode. Caller needs to explicitly
* do this outside rmap routines. * do this outside rmap routines.
*/ */
VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); VM_BUG_ON(!anon && !(flags & TTU_RMAP_LOCKED));
if (!anon && huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
flush_tlb_range(vma, range.start, range.end); flush_tlb_range(vma, range.start, range.end);
mmu_notifier_invalidate_range(mm, range.start, mmu_notifier_invalidate_range(mm, range.start,
range.end); range.end);
@ -1576,7 +1576,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
page_vma_mapped_walk_done(&pvmw); page_vma_mapped_walk_done(&pvmw);
break; break;
} }
}
pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
} else { } else {
flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
@ -1906,6 +1905,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
PageAnonExclusive(subpage); PageAnonExclusive(subpage);
if (folio_test_hugetlb(folio)) { if (folio_test_hugetlb(folio)) {
bool anon = folio_test_anon(folio);
/* /*
* huge_pmd_unshare may unmap an entire PMD page. * huge_pmd_unshare may unmap an entire PMD page.
* There is no way of knowing exactly which PMDs may * There is no way of knowing exactly which PMDs may
@ -1915,15 +1916,13 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
*/ */
flush_cache_range(vma, range.start, range.end); flush_cache_range(vma, range.start, range.end);
if (!folio_test_anon(folio)) {
/* /*
* To call huge_pmd_unshare, i_mmap_rwsem must be * To call huge_pmd_unshare, i_mmap_rwsem must be
* held in write mode. Caller needs to explicitly * held in write mode. Caller needs to explicitly
* do this outside rmap routines. * do this outside rmap routines.
*/ */
VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); VM_BUG_ON(!anon && !(flags & TTU_RMAP_LOCKED));
if (!anon && huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
flush_tlb_range(vma, range.start, range.end); flush_tlb_range(vma, range.start, range.end);
mmu_notifier_invalidate_range(mm, range.start, mmu_notifier_invalidate_range(mm, range.start,
range.end); range.end);
@ -1940,7 +1939,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
page_vma_mapped_walk_done(&pvmw); page_vma_mapped_walk_done(&pvmw);
break; break;
} }
}
/* Nuke the hugetlb page table entry */ /* Nuke the hugetlb page table entry */
pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);