* [PATCH] mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation.
@ 2022-04-04 16:53 Zi Yan
2022-04-04 18:28 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: Zi Yan @ 2022-04-04 16:53 UTC (permalink / raw)
To: linux-mm
Cc: Matthew Wilcox, Michal Hocko, Naoya Horiguchi, Andrew Morton,
linux-kernel, Zi Yan, Naoya Horiguchi
From: Zi Yan <ziy@nvidia.com>
With folios support, it is possible to have other than HPAGE_PMD_ORDER
THPs, in the form of folios, in the system. Use thp_order() to correctly
determine the source page order during migration.
Fixes: d68eccad3706 ("mm/filemap: Allow large folios to be added to the page cache")
Reported-by: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Link: https://lore.kernel.org/linux-mm/20220404132908.GA785673@u2004/
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
mm/mempolicy.c | 2 +-
mm/migrate.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 6b34c5d5e65a..88a74bc4cba5 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1209,7 +1209,7 @@ static struct page *new_page(struct page *page, unsigned long start)
struct page *thp;
thp = alloc_hugepage_vma(GFP_TRANSHUGE, vma, address,
- HPAGE_PMD_ORDER);
+ thp_order(page));
if (!thp)
return NULL;
prep_transhuge_page(thp);
diff --git a/mm/migrate.c b/mm/migrate.c
index 4639dfc2b7ee..b58b96fdb174 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1553,7 +1553,7 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
*/
gfp_mask &= ~__GFP_RECLAIM;
gfp_mask |= GFP_TRANSHUGE;
- order = HPAGE_PMD_ORDER;
+ order = thp_order(page);
}
zidx = zone_idx(page_zone(page));
if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
--
2.35.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation.
2022-04-04 16:53 [PATCH] mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation Zi Yan
@ 2022-04-04 18:28 ` Andrew Morton
2022-04-04 18:37 ` Zi Yan
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2022-04-04 18:28 UTC (permalink / raw)
To: Zi Yan
Cc: Zi Yan, linux-mm, Matthew Wilcox, Michal Hocko, Naoya Horiguchi,
linux-kernel, Naoya Horiguchi
On Mon, 4 Apr 2022 12:53:25 -0400 Zi Yan <zi.yan@sent.com> wrote:
> From: Zi Yan <ziy@nvidia.com>
>
> With folios support, it is possible to have other than HPAGE_PMD_ORDER
> THPs, in the form of folios, in the system. Use thp_order() to correctly
> determine the source page order during migration.
Changelog doesn't describe the end user visible effects of the bug.
And it really should, because
> Link: https://lore.kernel.org/linux-mm/20220404132908.GA785673@u2004/
it fixes a kernel crash!
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation.
2022-04-04 18:28 ` Andrew Morton
@ 2022-04-04 18:37 ` Zi Yan
0 siblings, 0 replies; 3+ messages in thread
From: Zi Yan @ 2022-04-04 18:37 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, Matthew Wilcox, Michal Hocko, Naoya Horiguchi,
linux-kernel, Naoya Horiguchi
[-- Attachment #1: Type: text/plain, Size: 1025 bytes --]
On 4 Apr 2022, at 14:28, Andrew Morton wrote:
> On Mon, 4 Apr 2022 12:53:25 -0400 Zi Yan <zi.yan@sent.com> wrote:
>
>> From: Zi Yan <ziy@nvidia.com>
>>
>> With folios support, it is possible to have other than HPAGE_PMD_ORDER
>> THPs, in the form of folios, in the system. Use thp_order() to correctly
>> determine the source page order during migration.
>
> Changelog doesn't describe the end user visible effects of the bug.
> And it really should, because
>
>> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flinux-mm%2F20220404132908.GA785673%40u2004%2F&data=04%7C01%7Cziy%40nvidia.com%7Cbf27ebf19d8a49a9b4b008da1668dc09%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C637846936880192108%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=pgvzV3wv6icqkMaWY2koB9X4VqlPMaSHeB8r7%2Fv1938%3D&reserved=0
>
> it fixes a kernel crash!
Thank you for adding the information.
--
Best Regards,
Yan, Zi
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-04-04 16:53 [PATCH] mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation Zi Yan
2022-04-04 18:28 ` Andrew Morton
2022-04-04 18:37 ` Zi Yan
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