The patch titled
Subject: Documentation/mm: update references to __m[un]lock_page() to *_folio()
has been added to the -mm mm-unstable branch. Its filename is
documentation-mm-update-references-to-__mlock_page-to-_folio.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/documentation-mm-update-references-to-__mlock_page-to-_folio.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Subject: Documentation/mm: update references to __m[un]lock_page() to *_folio()
Date: Thu, 12 Jan 2023 12:39:32 +0000
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Additionally, correct the outdated reference to __pagevec_lru_add_fn(),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, replace
reference to lru_cache_add_inactive_or_unevictable() with the modern folio
equivalent folio_add_lru_vma() and reference folio flags by the flag name
rather than accessor.
Link: https://lkml.kernel.org/r/898c487169d98a7f09c1c1e57a7dfdc2b3f6bf0f.1673526881.git.lstoakes@xxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/mm/unevictable-lru.rst | 30 ++++++++++++-------------
1 file changed, 15 insertions(+), 15 deletions(-)
--- a/Documentation/mm/unevictable-lru.rst~documentation-mm-update-references-to-__mlock_page-to-_folio
+++ a/Documentation/mm/unevictable-lru.rst
@@ -308,22 +308,22 @@ do end up getting faulted into this VM_L
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
+it is a newly allocated anonymous page, folio_add_lru_vma() 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 PG_mlocked 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 PG_unevictable, 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.
+mlock_count in place of LRU threading). Or if the page was already PG_lru
+and PG_unevictable and PG_mlocked, 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
@@ -377,8 +377,8 @@ that it is munlock() being performed.
munlock_page() uses the mlock pagevec to batch up work to be done under
lru_lock by __munlock_page(). __munlock_page() decrements the page's
-mlock_count, and when that reaches 0 it clears PageMlocked and clears
-PageUnevictable, moving the page from unevictable state to inactive LRU.
+mlock_count, and when that reaches 0 it clears PG_mlocked and clears
+PG_unevictable, moving the page from unevictable state to inactive LRU.
But in practice that may not work ideally: the page may not yet have reached
"the unevictable LRU", or it may have been temporarily isolated from it. In
@@ -488,8 +488,8 @@ munlock_vma_page(), which calls munlock_
munlock_page() uses the mlock pagevec to batch up work to be done under
lru_lock by __munlock_page(). __munlock_page() decrements the page's
-mlock_count, and when that reaches 0 it clears PageMlocked and clears
-PageUnevictable, moving the page from unevictable state to inactive LRU.
+mlock_count, and when that reaches 0 it clears PG_mlocked and clears
+PG_unevictable, moving the page from unevictable state to inactive LRU.
But in practice that may not work ideally: the page may not yet have reached
"the unevictable LRU", or it may have been temporarily isolated from it. In
@@ -515,7 +515,7 @@ munlocking by clearing VM_LOCKED from a
present, if one of those pages were unmapped by truncation or hole punch before
mlock_pte_range() reached it, it would not be recognized as mlocked by this VMA,
and would not be counted out of mlock_count. In this rare case, a page may
-still appear as PageMlocked after it has been fully unmapped: and it is left to
+still appear as PG_mlocked after it has been fully unmapped: and it is left to
release_pages() (or __page_cache_release()) to clear it and update statistics
before freeing (this event is counted in /proc/vmstat unevictable_pgs_cleared,
which is usually 0).
@@ -527,7 +527,7 @@ Page Reclaim in shrink_*_list()
vmscan's shrink_active_list() culls any obviously unevictable pages -
i.e. !page_evictable(page) pages - diverting those to the unevictable list.
However, shrink_active_list() only sees unevictable pages that made it onto the
-active/inactive LRU lists. Note that these pages do not have PageUnevictable
+active/inactive LRU lists. Note that these pages do not have PG_unevictable
set - otherwise they would be on the unevictable list and shrink_active_list()
would never see them.
_
Patches currently in -mm which might be from lstoakes@xxxxxxxxx are
mm-vmalloc-correct-use-of-__gfp_nowarn-mask-in-__vmalloc_area_node.patch
selftest-vm-add-mremap-expand-merge-offset-test.patch
mm-pagevec-add-folio_batch_reinit.patch
mm-mlock-use-folios-and-a-folio-batch-internally.patch
m68k-mm-motorola-specify-pmd_page-type.patch
mm-mlock-update-the-interface-to-use-folios.patch
documentation-mm-update-references-to-__mlock_page-to-_folio.patch
