* [to-be-updated] mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch removed from -mm tree
@ 2026-06-30 2:26 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-06-30 2:26 UTC (permalink / raw)
To: mm-commits, ye.liu, akpm
The quilt patch titled
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
has been removed from the -mm tree. Its filename was
mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Ye Liu <ye.liu@linux.dev>
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
Date: Fri, 26 Jun 2026 10:45:40 +0800
Patch series "mm/page_owner: misc cleanups", v2.
This series collects a few cleanups for mm/page_owner.c that have been
accumulated while reading through the file. There is no functional change
-- the goal is to make the code easier to read and maintain.
Patch 1 consolidates three identical PageBuddy skip blocks into a single
skip_buddy_pages() helper, eliminating the duplication and keeping the
lockless-read comment in one place.
Patch 2 replaces the -1 magic number used for "never migrated" with a
local MIGRATE_REASON_NONE define, making the intent explicit at every use
site.
Patch 3 hoists the CONFIG_MEMCG guard out of print_page_owner_memcg()'s
body so that the real implementation and the empty stub are two clearly
separate definitions, the common kernel idiom.
Patch 4 adds a missing \n to the count_threshold debugfs attribute format
string so that cat(1) output is properly terminated.
Patch 5 moves free_ts_nsec from the allocation summary line to the free
section in __dump_page_owner(), grouping it with free_pid and free_tgid
where it logically belongs. This also makes the dump output consistent
with print_page_owner().
Patch 6 drops the redundant page_owner_ prefix from file-scoped static
symbols (stack_fops, threshold_fops, etc.). Since they cannot collide
across translation units, the prefix carries no information.
This patch (of 6):
Three places in page_owner.c duplicate the same pattern: check if a page
is PageBuddy, read its order via buddy_order_unsafe(), advance the pfn
past the buddy block if the order is valid, and continue.
Consolidate them into a single inline helper skip_buddy_pages(). The
function returns true (skip) for any buddy page and advances @pfn past the
block when the order is valid; returns false if the page is not a buddy
page and should be processed normally.
The old init_pages_in_zone() variant used "order > 0" as an extra guard
before advancing pfn, but the continue was unconditional and (1UL << 0) -
1 == 0, so the behaviour is identical. The comment about zone->lock is
preserved in the helper's kernel-doc.
No functional change.
Link: https://lore.kernel.org/20260626024550.25677-1-ye.liu@linux.dev
Link: https://lore.kernel.org/20260626024550.25677-2-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/page_owner.c | 52 +++++++++++++++++++++++-----------------------
1 file changed, 26 insertions(+), 26 deletions(-)
--- a/mm/page_owner.c~mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping
+++ a/mm/page_owner.c
@@ -422,6 +422,29 @@ void __folio_copy_owner(struct folio *ne
rcu_read_unlock();
}
+/*
+ * Check if a page is a buddy page and advance @pfn past the entire buddy block.
+ * This safely reads the buddy order without the zone lock, which may cause us
+ * to skip less than the full buddy block, but that is acceptable for page owner
+ * iteration purposes.
+ *
+ * Return: true if the page was skipped (caller should continue its loop),
+ * false if the page is not a buddy page and should be processed normally.
+ */
+static inline bool skip_buddy_pages(unsigned long *pfn, struct page *page)
+{
+ unsigned long order;
+
+ if (!PageBuddy(page))
+ return false;
+
+ order = buddy_order_unsafe(page);
+ if (order <= MAX_PAGE_ORDER)
+ *pfn += (1UL << order) - 1;
+
+ return true;
+}
+
void pagetypeinfo_showmixedcount_print(struct seq_file *m,
pg_data_t *pgdat, struct zone *zone)
{
@@ -461,14 +484,8 @@ void pagetypeinfo_showmixedcount_print(s
if (page_zone(page) != zone)
continue;
- if (PageBuddy(page)) {
- unsigned long freepage_order;
-
- freepage_order = buddy_order_unsafe(page);
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
@@ -697,13 +714,8 @@ read_page_owner(struct file *file, char
}
page = pfn_to_page(pfn);
- if (PageBuddy(page)) {
- unsigned long freepage_order = buddy_order_unsafe(page);
-
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
page_ext = page_ext_get(page);
if (unlikely(!page_ext))
@@ -798,20 +810,8 @@ static void init_pages_in_zone(struct zo
if (page_zone(page) != zone)
continue;
- /*
- * To avoid having to grab zone->lock, be a little
- * careful when reading buddy page order. The only
- * danger is that we skip too much and potentially miss
- * some early allocated pages, which is better than
- * heavy lock contention.
- */
- if (PageBuddy(page)) {
- unsigned long order = buddy_order_unsafe(page);
-
- if (order > 0 && order <= MAX_PAGE_ORDER)
- pfn += (1UL << order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
_
Patches currently in -mm which might be from ye.liu@linux.dev are
mm-page_owner-use-migrate_reason_none-instead-of-1-for-last_migrate_reason.patch
mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch
mm-page_owner-add-missing-newline-to-count_threshold-format-string.patch
mm-page_owner-move-free_ts_nsec-output-to-free-section-in-__dump_page_owner.patch
mm-page_owner-drop-redundant-page_owner-prefix-from-static-symbols.patch
mm-page_owner-clamp-skip_buddy_pages-pfn-advance-at-max_order_nr_pages-boundary.patch
mm-page_owner-use-memcg_data-snapshot-instead-of-pagememcgkmem-to-avoid-toctou-vm_bug_on.patch
^ permalink raw reply [flat|nested] 4+ messages in thread* [to-be-updated] mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch removed from -mm tree
@ 2026-07-01 23:57 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-07-01 23:57 UTC (permalink / raw)
To: mm-commits, ye.liu, akpm
The quilt patch titled
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
has been removed from the -mm tree. Its filename was
mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Ye Liu <ye.liu@linux.dev>
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
Date: Wed, 1 Jul 2026 09:22:27 +0800
Patch series "mm/page_owner: misc cleanups", v4.
This series collects a few cleanups for mm/page_owner.c that have been
accumulated while reading through the file. There is no functional change
-- the goal is to make the code easier to read and maintain.
Patch 1 consolidates three identical PageBuddy skip blocks into a single
skip_buddy_pages() helper, eliminating the duplication and keeping the
lockless-read comment in one place.
Patch 2 replaces the -1 magic number used for "never migrated" with a
proper MR_NEVER member in enum migrate_reason, adds the corresponding
"never_migrated" string in the MIGRATE_REASON trace macro, and updates the
GDB page_owner script to use MR_NEVER so that lx-dump-page-owner correctly
detects unmigrated pages.
Patch 3 follows up by converting the remaining 'int reason' parameters
throughout the migration and hugetlb callchains to 'enum migrate_reason',
making the type explicit and gaining compiler checking. The 'short
last_migrate_reason' struct field in page_owner is intentionally left as
'short' since it is per-page metadata where size matters.
Patch 4 hoists the CONFIG_MEMCG guard out of print_page_owner_memcg()'s
body so that the real implementation and the empty stub are two clearly
separate definitions, the common kernel idiom.
Patch 5 adds a missing \n to the count_threshold debugfs attribute format
string so that cat(1) output is properly terminated.
Patch 6 moves free_ts_nsec from the allocation summary line to the free
section in __dump_page_owner(), grouping it with free_pid and free_tgid
where it logically belongs. This also makes the dump output consistent
with print_page_owner().
Patch 7 drops the redundant page_owner_ prefix from file-scoped static
symbols (stack_fops, threshold_fops, etc.). Since they cannot collide
across translation units, the prefix carries no information.
This patch (of 7):
Three places in page_owner.c duplicate the same pattern: check if a page
is PageBuddy, read its order via buddy_order_unsafe(), advance the pfn
past the buddy block if the order is valid, and continue.
Consolidate them into a single inline helper skip_buddy_pages(). The
function returns true (skip) for any buddy page and advances @pfn past the
block when the order is valid; returns false if the page is not a buddy
page and should be processed normally.
The old init_pages_in_zone() variant used "order > 0" as an extra guard
before advancing pfn, but the continue was unconditional and (1UL << 0) -
1 == 0, so the behaviour is identical. The comment about zone->lock is
preserved in the helper's kernel-doc.
No functional change.
Link: https://lore.kernel.org/20260701012239.315262-1-ye.liu@linux.dev
Link: https://lore.kernel.org/20260701012239.315262-2-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/page_owner.c | 52 +++++++++++++++++++++++-----------------------
1 file changed, 26 insertions(+), 26 deletions(-)
--- a/mm/page_owner.c~mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping
+++ a/mm/page_owner.c
@@ -422,6 +422,29 @@ void __folio_copy_owner(struct folio *ne
rcu_read_unlock();
}
+/*
+ * Check if a page is a buddy page and advance @pfn past the entire buddy block.
+ * This safely reads the buddy order without the zone lock, which may cause us
+ * to skip less than the full buddy block, but that is acceptable for page owner
+ * iteration purposes.
+ *
+ * Return: true if the page was skipped (caller should continue its loop),
+ * false if the page is not a buddy page and should be processed normally.
+ */
+static inline bool skip_buddy_pages(unsigned long *pfn, struct page *page)
+{
+ unsigned long order;
+
+ if (!PageBuddy(page))
+ return false;
+
+ order = buddy_order_unsafe(page);
+ if (order <= MAX_PAGE_ORDER)
+ *pfn += (1UL << order) - 1;
+
+ return true;
+}
+
void pagetypeinfo_showmixedcount_print(struct seq_file *m,
pg_data_t *pgdat, struct zone *zone)
{
@@ -461,14 +484,8 @@ void pagetypeinfo_showmixedcount_print(s
if (page_zone(page) != zone)
continue;
- if (PageBuddy(page)) {
- unsigned long freepage_order;
-
- freepage_order = buddy_order_unsafe(page);
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
@@ -697,13 +714,8 @@ read_page_owner(struct file *file, char
}
page = pfn_to_page(pfn);
- if (PageBuddy(page)) {
- unsigned long freepage_order = buddy_order_unsafe(page);
-
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
page_ext = page_ext_get(page);
if (unlikely(!page_ext))
@@ -798,20 +810,8 @@ static void init_pages_in_zone(struct zo
if (page_zone(page) != zone)
continue;
- /*
- * To avoid having to grab zone->lock, be a little
- * careful when reading buddy page order. The only
- * danger is that we skip too much and potentially miss
- * some early allocated pages, which is better than
- * heavy lock contention.
- */
- if (PageBuddy(page)) {
- unsigned long order = buddy_order_unsafe(page);
-
- if (order > 0 && order <= MAX_PAGE_ORDER)
- pfn += (1UL << order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
_
Patches currently in -mm which might be from ye.liu@linux.dev are
mm-page_owner-add-mr_never-to-enum-migrate_reason-and-use-it-for-last_migrate_reason.patch
mm-use-enum-migrate_reason-instead-of-int-for-migration-reason-parameters.patch
mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch
mm-page_owner-add-missing-newline-to-count_threshold-format-string.patch
mm-page_owner-move-free_ts_nsec-output-to-free-section-in-__dump_page_owner.patch
mm-page_owner-drop-redundant-page_owner-prefix-from-static-symbols.patch
^ permalink raw reply [flat|nested] 4+ messages in thread* [to-be-updated] mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch removed from -mm tree
@ 2026-07-01 3:36 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-07-01 3:36 UTC (permalink / raw)
To: mm-commits, ye.liu, akpm
The quilt patch titled
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
has been removed from the -mm tree. Its filename was
mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Ye Liu <ye.liu@linux.dev>
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
Date: Tue, 30 Jun 2026 09:53:18 +0800
Patch series "mm/page_owner: misc cleanups", v3.
This series collects a few cleanups for mm/page_owner.c that have been
accumulated while reading through the file. There is no functional change
-- the goal is to make the code easier to read and maintain.
Patch 1 consolidates three identical PageBuddy skip blocks into a single
skip_buddy_pages() helper, eliminating the duplication and keeping the
lockless-read comment in one place.
Patch 2 replaces the -1 magic number used for "never migrated" with a
proper MR_NEVER member in enum migrate_reason, and adds the corresponding
"never_migrated" string in the MIGRATE_REASON trace macro.
Patch 3 follows up by converting the remaining 'int reason' parameters
throughout the migration and hugetlb callchains to 'enum migrate_reason',
making the type explicit and gaining compiler checking. The 'short
last_migrate_reason' struct field in page_owner is intentionally left as
'short' since it is per-page metadata where size matters.
Patch 4 hoists the CONFIG_MEMCG guard out of print_page_owner_memcg()'s
body so that the real implementation and the empty stub are two clearly
separate definitions, the common kernel idiom.
Patch 5 adds a missing \n to the count_threshold debugfs attribute format
string so that cat(1) output is properly terminated.
Patch 6 moves free_ts_nsec from the allocation summary line to the free
section in __dump_page_owner(), grouping it with free_pid and free_tgid
where it logically belongs. This also makes the dump output consistent
with print_page_owner().
Patch 7 drops the redundant page_owner_ prefix from file-scoped static
symbols (stack_fops, threshold_fops, etc.). Since they cannot collide
across translation units, the prefix carries no information.
This patch (of 7):
Three places in page_owner.c duplicate the same pattern: check if a page
is PageBuddy, read its order via buddy_order_unsafe(), advance the pfn
past the buddy block if the order is valid, and continue.
Consolidate them into a single inline helper skip_buddy_pages(). The
function returns true (skip) for any buddy page and advances @pfn past the
block when the order is valid; returns false if the page is not a buddy
page and should be processed normally.
The old init_pages_in_zone() variant used "order > 0" as an extra guard
before advancing pfn, but the continue was unconditional and (1UL << 0) -
1 == 0, so the behaviour is identical. The comment about zone->lock is
preserved in the helper's kernel-doc.
No functional change.
Link: https://lore.kernel.org/20260630015331.147174-1-ye.liu@linux.dev
Link: https://lore.kernel.org/20260630015331.147174-2-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/page_owner.c | 52 +++++++++++++++++++++++-----------------------
1 file changed, 26 insertions(+), 26 deletions(-)
--- a/mm/page_owner.c~mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping
+++ a/mm/page_owner.c
@@ -422,6 +422,29 @@ void __folio_copy_owner(struct folio *ne
rcu_read_unlock();
}
+/*
+ * Check if a page is a buddy page and advance @pfn past the entire buddy block.
+ * This safely reads the buddy order without the zone lock, which may cause us
+ * to skip less than the full buddy block, but that is acceptable for page owner
+ * iteration purposes.
+ *
+ * Return: true if the page was skipped (caller should continue its loop),
+ * false if the page is not a buddy page and should be processed normally.
+ */
+static inline bool skip_buddy_pages(unsigned long *pfn, struct page *page)
+{
+ unsigned long order;
+
+ if (!PageBuddy(page))
+ return false;
+
+ order = buddy_order_unsafe(page);
+ if (order <= MAX_PAGE_ORDER)
+ *pfn += (1UL << order) - 1;
+
+ return true;
+}
+
void pagetypeinfo_showmixedcount_print(struct seq_file *m,
pg_data_t *pgdat, struct zone *zone)
{
@@ -461,14 +484,8 @@ void pagetypeinfo_showmixedcount_print(s
if (page_zone(page) != zone)
continue;
- if (PageBuddy(page)) {
- unsigned long freepage_order;
-
- freepage_order = buddy_order_unsafe(page);
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
@@ -697,13 +714,8 @@ read_page_owner(struct file *file, char
}
page = pfn_to_page(pfn);
- if (PageBuddy(page)) {
- unsigned long freepage_order = buddy_order_unsafe(page);
-
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
page_ext = page_ext_get(page);
if (unlikely(!page_ext))
@@ -798,20 +810,8 @@ static void init_pages_in_zone(struct zo
if (page_zone(page) != zone)
continue;
- /*
- * To avoid having to grab zone->lock, be a little
- * careful when reading buddy page order. The only
- * danger is that we skip too much and potentially miss
- * some early allocated pages, which is better than
- * heavy lock contention.
- */
- if (PageBuddy(page)) {
- unsigned long order = buddy_order_unsafe(page);
-
- if (order > 0 && order <= MAX_PAGE_ORDER)
- pfn += (1UL << order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
_
Patches currently in -mm which might be from ye.liu@linux.dev are
a.patch
mm-page_owner-add-mr_never-to-enum-migrate_reason-and-use-it-for-last_migrate_reason.patch
mm-use-enum-migrate_reason-instead-of-int-for-migration-reason-parameters.patch
mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch
mm-page_owner-add-missing-newline-to-count_threshold-format-string.patch
mm-page_owner-move-free_ts_nsec-output-to-free-section-in-__dump_page_owner.patch
mm-page_owner-drop-redundant-page_owner-prefix-from-static-symbols.patch
mm-page_owner-clamp-skip_buddy_pages-pfn-advance-at-max_order_nr_pages-boundary.patch
mm-page_owner-use-memcg_data-snapshot-instead-of-pagememcgkmem-to-avoid-toctou-vm_bug_on.patch
^ permalink raw reply [flat|nested] 4+ messages in thread* [to-be-updated] mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch removed from -mm tree
@ 2026-06-28 2:31 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-06-28 2:31 UTC (permalink / raw)
To: mm-commits, ye.liu, akpm
The quilt patch titled
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
has been removed from the -mm tree. Its filename was
mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Ye Liu <ye.liu@linux.dev>
Subject: mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping
Date: Tue, 23 Jun 2026 14:52:26 +0800
Three places in page_owner.c duplicate the same pattern: check if a page
is PageBuddy, read its order via buddy_order_unsafe(), advance the pfn
past the buddy block if the order is valid, and continue.
Consolidate them into a single inline helper skip_buddy_pages(). The
function returns true (skip) for any buddy page and advances @pfn past the
block when the order is valid; returns false if the page is not a buddy
page and should be processed normally.
The old init_pages_in_zone() variant used "order > 0" as an extra guard
before advancing pfn, but the continue was unconditional and (1UL << 0) -
1 == 0, so the behaviour is identical. The comment about zone->lock is
preserved in the helper's kernel-doc.
No functional change.
Link: https://lore.kernel.org/20260623065234.31866-2-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/page_owner.c | 52 +++++++++++++++++++++++-----------------------
1 file changed, 26 insertions(+), 26 deletions(-)
--- a/mm/page_owner.c~mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping
+++ a/mm/page_owner.c
@@ -422,6 +422,29 @@ void __folio_copy_owner(struct folio *ne
rcu_read_unlock();
}
+/*
+ * Check if a page is a buddy page and advance @pfn past the entire buddy block.
+ * This safely reads the buddy order without the zone lock, which may cause us
+ * to skip less than the full buddy block, but that is acceptable for page owner
+ * iteration purposes.
+ *
+ * Return: true if the page was skipped (caller should continue its loop),
+ * false if the page is not a buddy page and should be processed normally.
+ */
+static inline bool skip_buddy_pages(unsigned long *pfn, struct page *page)
+{
+ unsigned long order;
+
+ if (!PageBuddy(page))
+ return false;
+
+ order = buddy_order_unsafe(page);
+ if (order <= MAX_PAGE_ORDER)
+ *pfn += (1UL << order) - 1;
+
+ return true;
+}
+
void pagetypeinfo_showmixedcount_print(struct seq_file *m,
pg_data_t *pgdat, struct zone *zone)
{
@@ -461,14 +484,8 @@ void pagetypeinfo_showmixedcount_print(s
if (page_zone(page) != zone)
continue;
- if (PageBuddy(page)) {
- unsigned long freepage_order;
-
- freepage_order = buddy_order_unsafe(page);
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
@@ -697,13 +714,8 @@ read_page_owner(struct file *file, char
}
page = pfn_to_page(pfn);
- if (PageBuddy(page)) {
- unsigned long freepage_order = buddy_order_unsafe(page);
-
- if (freepage_order <= MAX_PAGE_ORDER)
- pfn += (1UL << freepage_order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
page_ext = page_ext_get(page);
if (unlikely(!page_ext))
@@ -798,20 +810,8 @@ static void init_pages_in_zone(struct zo
if (page_zone(page) != zone)
continue;
- /*
- * To avoid having to grab zone->lock, be a little
- * careful when reading buddy page order. The only
- * danger is that we skip too much and potentially miss
- * some early allocated pages, which is better than
- * heavy lock contention.
- */
- if (PageBuddy(page)) {
- unsigned long order = buddy_order_unsafe(page);
-
- if (order > 0 && order <= MAX_PAGE_ORDER)
- pfn += (1UL << order) - 1;
+ if (skip_buddy_pages(&pfn, page))
continue;
- }
if (PageReserved(page))
continue;
_
Patches currently in -mm which might be from ye.liu@linux.dev are
a.patch
mm-page_owner-use-migrate_reason_none-instead-of-1-for-last_migrate_reason.patch
mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch
mm-page_owner-add-missing-newline-to-count_threshold-format-string.patch
mm-page_owner-move-free_ts_nsec-output-to-free-section-in-__dump_page_owner.patch
mm-page_owner-drop-redundant-page_owner-prefix-from-static-symbols.patch
mm-page_owner-clamp-skip_buddy_pages-pfn-advance-at-max_order_nr_pages-boundary.patch
mm-page_owner-use-memcg_data-snapshot-instead-of-pagememcgkmem-to-avoid-toctou-vm_bug_on.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-07-01 23:57 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2026-06-30 2:26 [to-be-updated] mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch removed from -mm tree Andrew Morton
-- strict thread matches above, loose matches on Subject: below --
2026-07-01 23:57 Andrew Morton
2026-07-01 3:36 Andrew Morton
2026-06-28 2:31 Andrew Morton
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