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mm: introduce pte_move_swp_offset() helper which can move offset bidirectionally

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There could arise a necessity to obtain the first pte_t from a swap pte_t
located in the middle.  For instance, this may occur within the context of
do_swap_page(), where a page fault can potentially occur in any PTE of a
large folio.  To address this, the following patch introduces
pte_move_swp_offset(), a function capable of bidirectional movement by a
specified delta argument.  Consequently, pte_next_swp_offset() will
directly invoke it with delta = 1.

Link: https://lkml.kernel.org/r/20240529082824.150954-4-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Suggested-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chuanhua Han <hanchuanhua@oppo.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gao Xiang <xiang@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Barry Song 2024-05-29 20:28:21 +12:00 committed by Andrew Morton
parent 54f7a49c20
commit 3f9abcaa3e
1 changed files with 21 additions and 4 deletions
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25
mm/internal.h
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@ -211,18 +211,21 @@ static inline int folio_pte_batch(struct folio *folio, unsigned long addr,
}
/**
* pte_next_swp_offset - Increment the swap entry offset field of a swap pte.
* pte_move_swp_offset - Move the swap entry offset field of a swap pte
* forward or backward by delta
* @pte: The initial pte state; is_swap_pte(pte) must be true and
* non_swap_entry() must be false.
* @delta: The direction and the offset we are moving; forward if delta
* is positive; backward if delta is negative
*
* Increments the swap offset, while maintaining all other fields, including
* Moves the swap offset, while maintaining all other fields, including
* swap type, and any swp pte bits. The resulting pte is returned.
*/
static inline pte_t pte_next_swp_offset(pte_t pte)
static inline pte_t pte_move_swp_offset(pte_t pte, long delta)
{
swp_entry_t entry = pte_to_swp_entry(pte);
pte_t new = __swp_entry_to_pte(__swp_entry(swp_type(entry),
(swp_offset(entry) + 1)));
(swp_offset(entry) + delta)));
if (pte_swp_soft_dirty(pte))
new = pte_swp_mksoft_dirty(new);
@ -234,6 +237,20 @@ static inline pte_t pte_next_swp_offset(pte_t pte)
return new;
}
/**
* pte_next_swp_offset - Increment the swap entry offset field of a swap pte.
* @pte: The initial pte state; is_swap_pte(pte) must be true and
* non_swap_entry() must be false.
*
* Increments the swap offset, while maintaining all other fields, including
* swap type, and any swp pte bits. The resulting pte is returned.
*/
static inline pte_t pte_next_swp_offset(pte_t pte)
{
return pte_move_swp_offset(pte, 1);
}
/**
* swap_pte_batch - detect a PTE batch for a set of contiguous swap entries
* @start_ptep: Page table pointer for the first entry.