* + mm-sparse-vmemmap-open-code-init_compound_tail.patch added to mm-unstable branch
@ 2026-09-17 1:36 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-09-17 1:36 UTC (permalink / raw)
To: mm-commits, songmuchun, akpm
The patch titled
Subject: mm/sparse-vmemmap: open-code init_compound_tail()
has been added to the -mm mm-unstable branch. Its filename is
mm-sparse-vmemmap-open-code-init_compound_tail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-sparse-vmemmap-open-code-init_compound_tail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm/sparse-vmemmap: open-code init_compound_tail()
Date: Wed, 16 Sep 2026 14:43:33 +0800
init_compound_tail() is only used by vmemmap_shared_tail_page(), where the
shared tail page setup intentionally passes NULL as the compound head.
Keeping this helper in mm/internal.h exposes that special case to the rest
of the MM code and can make the NULL head argument look generally valid.
Open-code the initialization at the only call site so the special-case use
stays local to sparse vmemmap optimization.
No functional change intended.
Link: https://lore.kernel.org/20260916064341.1825793-4-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
---
mm/internal.h | 9 ---------
mm/sparse-vmemmap.c | 5 ++++-
2 files changed, 4 insertions(+), 10 deletions(-)
--- a/mm/internal.h~mm-sparse-vmemmap-open-code-init_compound_tail
+++ a/mm/internal.h
@@ -786,15 +786,6 @@ static inline void prep_compound_tail(st
VM_WARN_ON_ONCE(tail->private);
}
-static inline void init_compound_tail(struct page *tail,
- const struct page *head, unsigned int order, struct zone *zone)
-{
- atomic_set(&tail->_mapcount, -1);
- set_page_node(tail, zone_to_nid(zone));
- set_page_zone(tail, zone_idx(zone));
- prep_compound_tail(tail, head, order);
-}
-
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
/*
--- a/mm/sparse-vmemmap.c~mm-sparse-vmemmap-open-code-init_compound_tail
+++ a/mm/sparse-vmemmap.c
@@ -189,7 +189,10 @@ struct page __ref *vmemmap_shared_tail_p
for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++) {
page = (struct page *)addr + i;
mm_zero_struct_page(page);
- init_compound_tail(page, NULL, order, zone);
+ atomic_set(&page->_mapcount, -1);
+ set_page_node(page, zone_to_nid(zone));
+ set_page_zone(page, zone_idx(zone));
+ prep_compound_tail(page, NULL, order);
}
page = virt_to_page(addr);
_
Patches currently in -mm which might be from songmuchun@bytedance.com are
mm-sparse-relax-struct-mem_section-size-constraints.patch
mm-sparse-vmemmap-rename-hvo-order-macros.patch
mm-mm_init-skip-initializing-shared-vmemmap-tail-pages.patch
mm-sparse-vmemmap-initialize-shared-tail-vmemmap-pages-on-allocation.patch
mm-sparse-vmemmap-support-section-based-vmemmap-accounting.patch
mm-mm_init-factor-out-pfn_to_zone.patch
mm-sparse-vmemmap-move-helpers-ahead-of-future-callers.patch
mm-sparse-vmemmap-support-section-based-vmemmap-optimization.patch
mm-sparse-initialize-memory-sections-earlier.patch
mm-hugetlb-switch-hugetlb-to-section-based-vmemmap-optimization.patch
mm-sparse-vmemmap-remove-sparsemem_vmemmap_preinit-support.patch
mm-sparse-inline-usemap-allocation-into-sparse_init_nid.patch
mm-sparse-remove-section_map_size.patch
mm-hugetlb-remove-huge_bootmem_hvo.patch
mm-hugetlb-remove-huge_bootmem_cma.patch
mm-hugetlb-localize-struct-huge_bootmem_page.patch
mm-hugetlb-localize-huge_bootmem_zones_valid.patch
mm-sparse-vmemmap-introduce-config_vmemmap_optimization.patch
mm-sparse-vmemmap-introduce-config_vmemmap_optimization-fix.patch
mm-sparse-vmemmap-factor-out-shared-vmemmap-tail-page-allocation.patch
mm-sparse-vmemmap-open-code-init_compound_tail.patch
mm-sparse-vmemmap-prepare-dax-vmemmap-population-for-compound-page-orders.patch
mm-sparse-vmemmap-set-compound-page-order-for-device-dax.patch
mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch
powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-drop-the-extra-tail-page-from-device-dax-reservation.patch
mm-sparse-vmemmap-drop-unused-section_nr_vmemmap_pages-arguments.patch
documentation-mm-update-dax-vmemmap-deduplication-docs.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + mm-sparse-vmemmap-open-code-init_compound_tail.patch added to mm-unstable branch
@ 2026-09-27 5:51 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-09-27 5:51 UTC (permalink / raw)
To: mm-commits, muchun.song, akpm
The patch titled
Subject: mm/sparse-vmemmap: open-code init_compound_tail()
has been added to the -mm mm-unstable branch. Its filename is
mm-sparse-vmemmap-open-code-init_compound_tail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-sparse-vmemmap-open-code-init_compound_tail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Muchun Song <muchun.song@linux.dev>
Subject: mm/sparse-vmemmap: open-code init_compound_tail()
Date: Sun, 27 Sep 2026 10:54:33 +0800
init_compound_tail() is only used by vmemmap_shared_tail_page(), where
the shared tail page setup intentionally passes NULL as the compound head.
Keeping this helper in mm/internal.h exposes that special case to the rest
of the MM code and can make the NULL head argument look generally valid.
Open-code the initialization at the only call site so the special-case use
stays local to sparse vmemmap optimization.
No functional change intended.
Link: https://lore.kernel.org/20260927025441.741633-5-songmuchun@bytedance.com
Signed-off-by: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <chleroy@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Lance Yang <lance.yang@linux.dev>
---
mm/internal.h | 9 ---------
mm/sparse-vmemmap.c | 5 ++++-
2 files changed, 4 insertions(+), 10 deletions(-)
--- a/mm/internal.h~mm-sparse-vmemmap-open-code-init_compound_tail
+++ a/mm/internal.h
@@ -786,15 +786,6 @@ static inline void prep_compound_tail(st
VM_WARN_ON_ONCE(tail->private);
}
-static inline void init_compound_tail(struct page *tail,
- const struct page *head, unsigned int order, struct zone *zone)
-{
- atomic_set(&tail->_mapcount, -1);
- set_page_node(tail, zone_to_nid(zone));
- set_page_zone(tail, zone_idx(zone));
- prep_compound_tail(tail, head, order);
-}
-
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
/*
--- a/mm/sparse-vmemmap.c~mm-sparse-vmemmap-open-code-init_compound_tail
+++ a/mm/sparse-vmemmap.c
@@ -217,7 +217,10 @@ struct page __ref *vmemmap_shared_tail_p
for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++) {
page = (struct page *)addr + i;
mm_zero_struct_page(page);
- init_compound_tail(page, NULL, order, zone);
+ atomic_set(&page->_mapcount, -1);
+ set_page_node(page, zone_to_nid(zone));
+ set_page_zone(page, zone_idx(zone));
+ prep_compound_tail(page, NULL, order);
}
page = virt_to_page(addr);
_
Patches currently in -mm which might be from muchun.song@linux.dev are
mm-sparse-vmemmap-factor-out-shared-vmemmap-tail-page-allocation.patch
mm-sparse-vmemmap-allocate-shared-tail-page-array-dynamically.patch
mm-sparse-vmemmap-introduce-config_vmemmap_optimization.patch
mm-sparse-vmemmap-open-code-init_compound_tail.patch
mm-sparse-vmemmap-prepare-dax-vmemmap-population-for-compound-page-orders.patch
mm-sparse-vmemmap-set-compound-page-order-for-device-dax.patch
mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch
powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-drop-the-extra-tail-page-from-device-dax-reservation.patch
mm-sparse-vmemmap-drop-unused-section_nr_vmemmap_pages-arguments.patch
documentation-mm-update-dax-vmemmap-deduplication-docs.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + mm-sparse-vmemmap-open-code-init_compound_tail.patch added to mm-unstable branch
@ 2026-09-30 19:01 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-09-30 19:01 UTC (permalink / raw)
To: mm-commits, muchun.song, akpm
The patch titled
Subject: mm/sparse-vmemmap: open-code init_compound_tail()
has been added to the -mm mm-unstable branch. Its filename is
mm-sparse-vmemmap-open-code-init_compound_tail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-sparse-vmemmap-open-code-init_compound_tail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Muchun Song <muchun.song@linux.dev>
Subject: mm/sparse-vmemmap: open-code init_compound_tail()
Date: Wed, 30 Sep 2026 22:06:19 +0800
init_compound_tail() is only used by vmemmap_shared_tail_page(), where the
shared tail page setup intentionally passes NULL as the compound head.
Keeping this helper in mm/internal.h exposes that special case to the rest
of the MM code and can make the NULL head argument look generally valid.
Open-code the initialization at the only call site so the special-case use
stays local to sparse vmemmap optimization.
No functional change intended.
Link: https://lore.kernel.org/20260930140627.57431-5-songmuchun@bytedance.com
Signed-off-by: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <chleroy@kernel.org>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Lance Yang <lance.yang@linux.dev>
---
mm/internal.h | 9 ---------
mm/sparse-vmemmap.c | 5 ++++-
2 files changed, 4 insertions(+), 10 deletions(-)
--- a/mm/internal.h~mm-sparse-vmemmap-open-code-init_compound_tail
+++ a/mm/internal.h
@@ -786,15 +786,6 @@ static inline void prep_compound_tail(st
VM_WARN_ON_ONCE(tail->private);
}
-static inline void init_compound_tail(struct page *tail,
- const struct page *head, unsigned int order, struct zone *zone)
-{
- atomic_set(&tail->_mapcount, -1);
- set_page_node(tail, zone_to_nid(zone));
- set_page_zone(tail, zone_idx(zone));
- prep_compound_tail(tail, head, order);
-}
-
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
/*
--- a/mm/sparse-vmemmap.c~mm-sparse-vmemmap-open-code-init_compound_tail
+++ a/mm/sparse-vmemmap.c
@@ -221,7 +221,10 @@ struct page __ref *vmemmap_shared_tail_p
for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++) {
page = (struct page *)addr + i;
mm_zero_struct_page(page);
- init_compound_tail(page, NULL, order, zone);
+ atomic_set(&page->_mapcount, -1);
+ set_page_node(page, zone_to_nid(zone));
+ set_page_zone(page, zone_idx(zone));
+ prep_compound_tail(page, NULL, order);
}
page = virt_to_page(addr);
_
Patches currently in -mm which might be from muchun.song@linux.dev are
mm-sparse-vmemmap-factor-out-shared-vmemmap-tail-page-allocation.patch
mm-sparse-vmemmap-allocate-shared-tail-page-array-dynamically.patch
mm-sparse-vmemmap-introduce-config_vmemmap_optimization.patch
mm-sparse-vmemmap-open-code-init_compound_tail.patch
mm-sparse-vmemmap-prepare-dax-vmemmap-population-for-compound-page-orders.patch
mm-sparse-vmemmap-set-compound-page-order-for-device-dax.patch
mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages-fix.patch
mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch
powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages.patch
powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages-fix.patch
mm-sparse-vmemmap-drop-the-extra-tail-page-from-device-dax-reservation.patch
mm-sparse-vmemmap-drop-unused-section_nr_vmemmap_pages-arguments.patch
documentation-mm-update-dax-vmemmap-deduplication-docs.patch
mm-sparse-vmemmap-drop-vmemmap_populate_dax.patch
mm-sparse-vmemmap-support-device-dax-in-common-vmemmap-path.patch
mm-sparse-vmemmap-drop-device-dax-specific-population-path.patch
mm-sparse-vmemmap-remove-the-unused-ptpfn-argument.patch
mm-sparse-vmemmap-open-code-vmemmap_populate_address.patch
mm-mm_init-add-zone-mismatch-warning-during-page-init.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-09-27 5:51 Andrew Morton
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