* [PATCH v2] mm/page_alloc: remove VM_BUG_ON()s from pindex helpers
@ 2026-05-26 11:28 Brendan Jackman
2026-05-26 11:34 ` Vlastimil Babka (SUSE)
2026-06-17 11:22 ` David Hildenbrand (Arm)
0 siblings, 2 replies; 3+ messages in thread
From: Brendan Jackman @ 2026-05-26 11:28 UTC (permalink / raw)
To: Andrew Morton, Vlastimil Babka, Suren Baghdasaryan, Michal Hocko,
Johannes Weiner, Zi Yan
Cc: linux-mm, linux-kernel, Brendan Jackman
Vlastimil pointed out that the VM_BUG_ON()s have fallen out of
favour, so remove them.
Suggested-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Link: https://lore.kernel.org/all/4074a816-9e75-45a6-8141-25459bcc106b@kernel.org/
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
Changes in v2:
- Rebased onto mm-new, removed VM_BUG_ON()s
- Link to v1: https://lore.kernel.org/r/20260513-page_alloc-unmapped-prep-v1-0-dacdf5402be8@google.com
---
mm/page_alloc.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1b5b1e556f76feadf21f3f44a9440fe883fb7651..e47679e7a9dbc772aa27f550a10aa8c0e95af55a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -653,13 +653,8 @@ static inline unsigned int order_to_pindex(int migratetype, int order)
if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
bool movable = migratetype == MIGRATE_MOVABLE;
- if (order > PAGE_ALLOC_COSTLY_ORDER) {
- VM_BUG_ON(!is_pmd_order(order));
-
+ if (order > PAGE_ALLOC_COSTLY_ORDER)
return NR_LOWORDER_PCP_LISTS + movable;
- }
- } else {
- VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
}
return (MIGRATE_PCPTYPES * order) + migratetype;
@@ -672,8 +667,6 @@ static inline int pindex_to_order(unsigned int pindex)
if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
if (pindex >= NR_LOWORDER_PCP_LISTS)
order = HPAGE_PMD_ORDER;
- } else {
- VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
}
return order;
---
base-commit: da0a06486ac3ce47c6ffb603d2fd332229d41592
change-id: 20260512-page_alloc-unmapped-prep-c3ae0381d58b
Best regards,
--
Brendan Jackman <jackmanb@google.com>
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH v2] mm/page_alloc: remove VM_BUG_ON()s from pindex helpers
2026-05-26 11:28 [PATCH v2] mm/page_alloc: remove VM_BUG_ON()s from pindex helpers Brendan Jackman
@ 2026-05-26 11:34 ` Vlastimil Babka (SUSE)
2026-06-17 11:22 ` David Hildenbrand (Arm)
1 sibling, 0 replies; 3+ messages in thread
From: Vlastimil Babka (SUSE) @ 2026-05-26 11:34 UTC (permalink / raw)
To: Brendan Jackman, Andrew Morton, Suren Baghdasaryan, Michal Hocko,
Johannes Weiner, Zi Yan
Cc: linux-mm, linux-kernel
On 5/26/26 1:28 PM, Brendan Jackman wrote:
> Vlastimil pointed out that the VM_BUG_ON()s have fallen out of
> favour, so remove them.
>
> Suggested-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
> Link: https://lore.kernel.org/all/4074a816-9e75-45a6-8141-25459bcc106b@kernel.org/
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Thanks.
> ---
> Changes in v2:
> - Rebased onto mm-new, removed VM_BUG_ON()s
> - Link to v1: https://lore.kernel.org/r/20260513-page_alloc-unmapped-prep-v1-0-dacdf5402be8@google.com
> ---
> mm/page_alloc.c | 9 +--------
> 1 file changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 1b5b1e556f76feadf21f3f44a9440fe883fb7651..e47679e7a9dbc772aa27f550a10aa8c0e95af55a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -653,13 +653,8 @@ static inline unsigned int order_to_pindex(int migratetype, int order)
> if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
> bool movable = migratetype == MIGRATE_MOVABLE;
>
> - if (order > PAGE_ALLOC_COSTLY_ORDER) {
> - VM_BUG_ON(!is_pmd_order(order));
> -
> + if (order > PAGE_ALLOC_COSTLY_ORDER)
> return NR_LOWORDER_PCP_LISTS + movable;
> - }
> - } else {
> - VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
> }
>
> return (MIGRATE_PCPTYPES * order) + migratetype;
> @@ -672,8 +667,6 @@ static inline int pindex_to_order(unsigned int pindex)
> if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
> if (pindex >= NR_LOWORDER_PCP_LISTS)
> order = HPAGE_PMD_ORDER;
> - } else {
> - VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
> }
>
> return order;
>
> ---
> base-commit: da0a06486ac3ce47c6ffb603d2fd332229d41592
> change-id: 20260512-page_alloc-unmapped-prep-c3ae0381d58b
>
> Best regards,
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v2] mm/page_alloc: remove VM_BUG_ON()s from pindex helpers
2026-05-26 11:28 [PATCH v2] mm/page_alloc: remove VM_BUG_ON()s from pindex helpers Brendan Jackman
2026-05-26 11:34 ` Vlastimil Babka (SUSE)
@ 2026-06-17 11:22 ` David Hildenbrand (Arm)
1 sibling, 0 replies; 3+ messages in thread
From: David Hildenbrand (Arm) @ 2026-06-17 11:22 UTC (permalink / raw)
To: Brendan Jackman, Andrew Morton, Vlastimil Babka,
Suren Baghdasaryan, Michal Hocko, Johannes Weiner, Zi Yan
Cc: linux-mm, linux-kernel
On 5/26/26 13:28, Brendan Jackman wrote:
> Vlastimil pointed out that the VM_BUG_ON()s have fallen out of
> favour, so remove them.
>
> Suggested-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
> Link: https://lore.kernel.org/all/4074a816-9e75-45a6-8141-25459bcc106b@kernel.org/
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-05-26 11:28 [PATCH v2] mm/page_alloc: remove VM_BUG_ON()s from pindex helpers Brendan Jackman
2026-05-26 11:34 ` Vlastimil Babka (SUSE)
2026-06-17 11:22 ` David Hildenbrand (Arm)
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