* + mm-huge_memory-update-folio-stat-after-successful-split.patch added to mm-new branch
@ 2025-10-15 0:03 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2025-10-15 0:03 UTC (permalink / raw)
To: mm-commits, ziy, ryan.roberts, npache, lorenzo.stoakes,
liam.howlett, lance.yang, dev.jain, david, baolin.wang, baohua,
richard.weiyang, akpm
The patch titled
Subject: mm/huge_memory: update folio stat after successful split
has been added to the -mm mm-new branch. Its filename is
mm-huge_memory-update-folio-stat-after-successful-split.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-update-folio-stat-after-successful-split.patch
This patch will later appear in the mm-new branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews. Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.
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 the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Wei Yang <richard.weiyang@gmail.com>
Subject: mm/huge_memory: update folio stat after successful split
Date: Tue, 14 Oct 2025 13:46:03 +0000
When a folio is successfully split, its statistics must be updated.
The current implementation complicates this process:
* It iterates over the resulting new folios.
* It uses a flag (@stop_split) to conditionally skip updating the stat
for the folio at @split_at during the loop.
* It then attempts to update the skipped stat on a subsequent failure
path.
This logic is unnecessarily hard to follow.
This commit refactors the code to update the folio statistics only after a
successful split. This makes the logic much cleaner and sets the stage
for further simplification of the stat-handling code.
Link: https://lkml.kernel.org/r/20251014134606.22543-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/huge_memory.c | 44 +++++++++++---------------------------------
1 file changed, 11 insertions(+), 33 deletions(-)
--- a/mm/huge_memory.c~mm-huge_memory-update-folio-stat-after-successful-split
+++ a/mm/huge_memory.c
@@ -3530,13 +3530,8 @@ static int __split_unmapped_folio(struct
bool is_anon = folio_test_anon(folio);
int order = folio_order(folio);
int start_order = uniform_split ? new_order : order - 1;
- bool stop_split = false;
struct folio *next;
int split_order;
- int ret = 0;
-
- if (is_anon)
- mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
folio_clear_has_hwpoisoned(folio);
@@ -3545,7 +3540,7 @@ static int __split_unmapped_folio(struct
* folio is split to new_order directly.
*/
for (split_order = start_order;
- split_order >= new_order && !stop_split;
+ split_order >= new_order;
split_order--) {
struct folio *end_folio = folio_next(folio);
int old_order = folio_order(folio);
@@ -3568,49 +3563,32 @@ static int __split_unmapped_folio(struct
else {
xas_set_order(xas, folio->index, split_order);
xas_try_split(xas, folio, old_order);
- if (xas_error(xas)) {
- ret = xas_error(xas);
- stop_split = true;
- }
+ if (xas_error(xas))
+ return xas_error(xas);
}
}
- if (!stop_split) {
- folio_split_memcg_refs(folio, old_order, split_order);
- split_page_owner(&folio->page, old_order, split_order);
- pgalloc_tag_split(folio, old_order, split_order);
-
- __split_folio_to_order(folio, old_order, split_order);
- }
+ folio_split_memcg_refs(folio, old_order, split_order);
+ split_page_owner(&folio->page, old_order, split_order);
+ pgalloc_tag_split(folio, old_order, split_order);
+ __split_folio_to_order(folio, old_order, split_order);
+ if (is_anon)
+ mod_mthp_stat(old_order, MTHP_STAT_NR_ANON, -1);
/*
* Iterate through after-split folios and update folio stats.
- * But in buddy allocator like split, the folio
- * containing the specified page is skipped until its order
- * is new_order, since the folio will be worked on in next
- * iteration.
*/
for (new_folio = folio; new_folio != end_folio; new_folio = next) {
next = folio_next(new_folio);
- /*
- * for buddy allocator like split, new_folio containing
- * @split_at page could be split again, thus do not
- * change stats yet. Wait until new_folio's order is
- * @new_order or stop_split is set to true by the above
- * xas_split() failure.
- */
- if (new_folio == page_folio(split_at)) {
+ if (new_folio == page_folio(split_at))
folio = new_folio;
- if (split_order != new_order && !stop_split)
- continue;
- }
if (is_anon)
mod_mthp_stat(folio_order(new_folio),
MTHP_STAT_NR_ANON, 1);
}
}
- return ret;
+ return 0;
}
bool non_uniform_split_supported(struct folio *folio, unsigned int new_order,
_
Patches currently in -mm which might be from richard.weiyang@gmail.com are
mm-compaction-check-the-range-to-pageblock_pfn_to_page-is-within-the-zone-first.patch
mm-compaction-fix-the-range-to-pageblock_pfn_to_page.patch
mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd.patch
mm-khugepaged-unify-pmd-folio-installation-with-map_anon_folio_pmd.patch
mm-huge_memory-only-get-folio_order-once-during-__folio_split.patch
mm-huge_memory-cache-folio-attribute-in-__split_unmapped_folio.patch
mm-huge_memory-update-folio-stat-after-successful-split.patch
mm-huge_memory-optimize-and-simplify-folio-stat-update-after-split.patch
mm-huge_memory-optimize-old_order-derivation-during-folio-splitting.patch
mm-huge_memory-remove-redundant-split_order-=-new_order-check-in-uniform_split.patch
^ permalink raw reply [flat|nested] 2+ messages in thread* + mm-huge_memory-update-folio-stat-after-successful-split.patch added to mm-new branch
@ 2025-10-22 21:45 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2025-10-22 21:45 UTC (permalink / raw)
To: mm-commits, ziy, ryan.roberts, npache, lorenzo.stoakes, lianux.mm,
liam.howlett, lance.yang, dev.jain, david, baolin.wang, baohua,
richard.weiyang, akpm
The patch titled
Subject: mm/huge_memory: update folio stat after successful split
has been added to the -mm mm-new branch. Its filename is
mm-huge_memory-update-folio-stat-after-successful-split.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-update-folio-stat-after-successful-split.patch
This patch will later appear in the mm-new branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews. Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.
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 the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Wei Yang <richard.weiyang@gmail.com>
Subject: mm/huge_memory: update folio stat after successful split
Date: Tue, 21 Oct 2025 21:21:40 +0000
The current implementation complicates this process:
* It iterates over the resulting new folios.
* It uses a flag (@stop_split) to conditionally skip updating the stat
for the folio at @split_at during the loop.
* It then attempts to update the skipped stat on a subsequent failure
path.
This logic is unnecessarily hard to follow.
This commit refactors the code to update the folio statistics only after a
successful split. This makes the logic much cleaner and sets the stage
for further simplification of the stat-handling code.
Link: https://lkml.kernel.org/r/20251021212142.25766-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: wang lian <lianux.mm@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/huge_memory.c | 44 +++++++++++---------------------------------
1 file changed, 11 insertions(+), 33 deletions(-)
--- a/mm/huge_memory.c~mm-huge_memory-update-folio-stat-after-successful-split
+++ a/mm/huge_memory.c
@@ -3609,13 +3609,8 @@ static int __split_unmapped_folio(struct
const bool is_anon = folio_test_anon(folio);
int order = folio_order(folio);
int start_order = uniform_split ? new_order : order - 1;
- bool stop_split = false;
struct folio *next;
int split_order;
- int ret = 0;
-
- if (is_anon)
- mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
folio_clear_has_hwpoisoned(folio);
@@ -3624,7 +3619,7 @@ static int __split_unmapped_folio(struct
* folio is split to new_order directly.
*/
for (split_order = start_order;
- split_order >= new_order && !stop_split;
+ split_order >= new_order;
split_order--) {
struct folio *end_folio = folio_next(folio);
int old_order = folio_order(folio);
@@ -3647,49 +3642,32 @@ static int __split_unmapped_folio(struct
else {
xas_set_order(xas, folio->index, split_order);
xas_try_split(xas, folio, old_order);
- if (xas_error(xas)) {
- ret = xas_error(xas);
- stop_split = true;
- }
+ if (xas_error(xas))
+ return xas_error(xas);
}
}
- if (!stop_split) {
- folio_split_memcg_refs(folio, old_order, split_order);
- split_page_owner(&folio->page, old_order, split_order);
- pgalloc_tag_split(folio, old_order, split_order);
-
- __split_folio_to_order(folio, old_order, split_order);
- }
+ folio_split_memcg_refs(folio, old_order, split_order);
+ split_page_owner(&folio->page, old_order, split_order);
+ pgalloc_tag_split(folio, old_order, split_order);
+ __split_folio_to_order(folio, old_order, split_order);
+ if (is_anon)
+ mod_mthp_stat(old_order, MTHP_STAT_NR_ANON, -1);
/*
* Iterate through after-split folios and update folio stats.
- * But in buddy allocator like split, the folio
- * containing the specified page is skipped until its order
- * is new_order, since the folio will be worked on in next
- * iteration.
*/
for (new_folio = folio; new_folio != end_folio; new_folio = next) {
next = folio_next(new_folio);
- /*
- * for buddy allocator like split, new_folio containing
- * @split_at page could be split again, thus do not
- * change stats yet. Wait until new_folio's order is
- * @new_order or stop_split is set to true by the above
- * xas_split() failure.
- */
- if (new_folio == page_folio(split_at)) {
+ if (new_folio == page_folio(split_at))
folio = new_folio;
- if (split_order != new_order && !stop_split)
- continue;
- }
if (is_anon)
mod_mthp_stat(folio_order(new_folio),
MTHP_STAT_NR_ANON, 1);
}
}
- return ret;
+ return 0;
}
bool non_uniform_split_supported(struct folio *folio, unsigned int new_order,
_
Patches currently in -mm which might be from richard.weiyang@gmail.com are
mm-compaction-check-the-range-to-pageblock_pfn_to_page-is-within-the-zone-first.patch
mm-compaction-fix-the-range-to-pageblock_pfn_to_page.patch
mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd.patch
mm-khugepaged-unify-pmd-folio-installation-with-map_anon_folio_pmd.patch
mm-huge_memory-only-get-folio_order-once-during-__folio_split.patch
mm-huge_memory-avoid-reinvoking-folio_test_anon.patch
mm-huge_memory-update-folio-stat-after-successful-split.patch
mm-huge_memory-optimize-and-simplify-folio-stat-update-after-split.patch
mm-huge_memory-optimize-old_order-derivation-during-folio-splitting.patch
^ permalink raw reply [flat|nested] 2+ messages in thread
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