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mm/huge_memory: remove stale locking logic from __split_huge_pmd()

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Let's remove the stale logic that was required for reuse_swap_page().

[akpm@linux-foundation.org: simplification, per Yang Shi]

Link: https://lkml.kernel.org/r/20220131162940.210846-10-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Liang Zhang <zhangliang5@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2022-03-24 18:13:56 -07:00 committed by Linus Torvalds
parent 55c62fa7c5
commit 7f7609175f
1 changed files with 4 additions and 36 deletions
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40
mm/huge_memory.c
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@ -2133,8 +2133,6 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
{
spinlock_t *ptl;
struct mmu_notifier_range range;
bool do_unlock_folio = false;
pmd_t _pmd;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
address & HPAGE_PMD_MASK,
@ -2153,42 +2151,12 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
goto out;
}
repeat:
if (pmd_trans_huge(*pmd)) {
if (!folio) {
folio = page_folio(pmd_page(*pmd));
/*
* An anonymous page must be locked, to ensure that a
* concurrent reuse_swap_page() sees stable mapcount;
* but reuse_swap_page() is not used on shmem or file,
* and page lock must not be taken when zap_pmd_range()
* calls __split_huge_pmd() while i_mmap_lock is held.
*/
if (folio_test_anon(folio)) {
if (unlikely(!folio_trylock(folio))) {
folio_get(folio);
_pmd = *pmd;
spin_unlock(ptl);
folio_lock(folio);
spin_lock(ptl);
if (unlikely(!pmd_same(*pmd, _pmd))) {
folio_unlock(folio);
folio_put(folio);
folio = NULL;
goto repeat;
}
folio_put(folio);
}
do_unlock_folio = true;
}
}
} else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
goto out;
__split_huge_pmd_locked(vma, pmd, range.start, freeze);
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) ||
is_pmd_migration_entry(*pmd))
__split_huge_pmd_locked(vma, pmd, range.start, freeze);
out:
spin_unlock(ptl);
if (do_unlock_folio)
folio_unlock(folio);
/*
* No need to double call mmu_notifier->invalidate_range() callback.
* They are 3 cases to consider inside __split_huge_pmd_locked():