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Subject[PATCH v2 4/4] Documentation/mm: Update references to __m[un]lock_page() to *_folio()
Date
We now pass folios to these functions, so update the documentation
accordingly.

Additionally, correct the outdated reference to __pagevec_lru_add_fn(), the
referenced action occurs in __munlock_folio() directly now.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
---
Documentation/mm/unevictable-lru.rst | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Documentation/mm/unevictable-lru.rst b/Documentation/mm/unevictable-lru.rst
index 4a0e158aa9ce..153629e0c100 100644
--- a/Documentation/mm/unevictable-lru.rst
+++ b/Documentation/mm/unevictable-lru.rst
@@ -308,22 +308,22 @@ do end up getting faulted into this VM_LOCKED VMA, they will be handled in the
fault path - which is also how mlock2()'s MLOCK_ONFAULT areas are handled.

For each PTE (or PMD) being faulted into a VMA, the page add rmap function
-calls mlock_vma_page(), which calls mlock_page() when the VMA is VM_LOCKED
+calls mlock_vma_page(), which calls mlock_folio() when the VMA is VM_LOCKED
(unless it is a PTE mapping of a part of a transparent huge page). Or when
it is a newly allocated anonymous page, lru_cache_add_inactive_or_unevictable()
-calls mlock_new_page() instead: similar to mlock_page(), but can make better
+calls mlock_new_folio() instead: similar to mlock_folio(), but can make better
judgments, since this page is held exclusively and known not to be on LRU yet.

-mlock_page() sets PageMlocked immediately, then places the page on the CPU's
-mlock pagevec, to batch up the rest of the work to be done under lru_lock by
-__mlock_page(). __mlock_page() sets PageUnevictable, initializes mlock_count
+mlock_folio() sets PageMlocked immediately, then places the page on the CPU's
+mlock folio batch, to batch up the rest of the work to be done under lru_lock by
+__mlock_folio(). __mlock_folio() sets PageUnevictable, initializes mlock_count
and moves the page to unevictable state ("the unevictable LRU", but with
mlock_count in place of LRU threading). Or if the page was already PageLRU
and PageUnevictable and PageMlocked, it simply increments the mlock_count.

But in practice that may not work ideally: the page may not yet be on an LRU, or
it may have been temporarily isolated from LRU. In such cases the mlock_count
-field cannot be touched, but will be set to 0 later when __pagevec_lru_add_fn()
+field cannot be touched, but will be set to 0 later when __munlock_folio()
returns the page to "LRU". Races prohibit mlock_count from being set to 1 then:
rather than risk stranding a page indefinitely as unevictable, always err with
mlock_count on the low side, so that when munlocked the page will be rescued to
--
2.39.0
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