From: Usama Arif <usama.arif@linux.dev>
To: Andrew Morton <akpm@linux-foundation.org>,
david@kernel.org, lorenzo.stoakes@oracle.com,
willy@infradead.org, linux-mm@kvack.org
Cc: fvdl@google.com, hannes@cmpxchg.org, riel@surriel.com,
shakeel.butt@linux.dev, kas@kernel.org, baohua@kernel.org,
dev.jain@arm.com, baolin.wang@linux.alibaba.com,
npache@redhat.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com,
Vlastimil Babka <vbabka@kernel.org>,
lance.yang@linux.dev, linux-kernel@vger.kernel.org,
kernel-team@meta.com, maddy@linux.ibm.com, mpe@ellerman.id.au,
linuxppc-dev@lists.ozlabs.org, hca@linux.ibm.com,
gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
linux-s390@vger.kernel.org
Subject: Re: [RFC v2 16/21] mm: thp: add THP_SPLIT_PMD_FAILED counter
Date: Thu, 26 Feb 2026 14:22:35 +0000 [thread overview]
Message-ID: <a108bab5-9b53-4b90-a102-cc6fc22bb389@linux.dev> (raw)
In-Reply-To: <20260226113233.3987674-17-usama.arif@linux.dev>
On 26/02/2026 11:23, Usama Arif wrote:
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 2519d579bc1d8..2dae46fff08ae 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -2067,8 +2067,10 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> pgtable_t pgtable = prealloc_pte;
>
> prealloc_pte = NULL;
> +
> if (!arch_needs_pgtable_deposit() && !pgtable &&
> vma_is_anonymous(vma)) {
> + count_vm_event(THP_SPLIT_PMD_FAILED);
> page_vma_mapped_walk_done(&pvmw);
> ret = false;
> break;
> @@ -2471,6 +2473,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
> prealloc_pte = NULL;
> if (!arch_needs_pgtable_deposit() && !pgtable &&
> vma_is_anonymous(vma)) {
> + count_vm_event(THP_SPLIT_PMD_FAILED);
> page_vma_mapped_walk_done(&pvmw);
> ret = false;
> break;
This will need to be guarded by CONFIG_TRANSPARENT_HUGEPAGE. Will need below diff in next series..
diff --git a/mm/rmap.c b/mm/rmap.c
index 2dae46fff08ae..9d74600951cf6 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2070,7 +2070,9 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
if (!arch_needs_pgtable_deposit() && !pgtable &&
vma_is_anonymous(vma)) {
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
count_vm_event(THP_SPLIT_PMD_FAILED);
+#endif
page_vma_mapped_walk_done(&pvmw);
ret = false;
break;
@@ -2473,7 +2475,9 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
prealloc_pte = NULL;
if (!arch_needs_pgtable_deposit() && !pgtable &&
vma_is_anonymous(vma)) {
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
count_vm_event(THP_SPLIT_PMD_FAILED);
+#endif
page_vma_mapped_walk_done(&pvmw);
ret = false;
break;
next prev parent reply other threads:[~2026-02-26 14:22 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-26 11:23 [RFC v2 00/21] mm: thp: lazy PTE page table allocation at PMD split Usama Arif
2026-02-26 11:23 ` [RFC v2 01/21] mm: thp: make split_huge_pmd functions return int for error propagation Usama Arif
2026-02-26 11:23 ` [RFC v2 02/21] mm: thp: propagate split failure from vma_adjust_trans_huge() Usama Arif
2026-02-26 11:23 ` [RFC v2 03/21] mm: thp: handle split failure in copy_huge_pmd() Usama Arif
2026-02-26 11:23 ` [RFC v2 04/21] mm: thp: handle split failure in do_huge_pmd_wp_page() Usama Arif
2026-02-26 11:23 ` [RFC v2 05/21] mm: thp: handle split failure in zap_pmd_range() Usama Arif
2026-02-26 11:23 ` [RFC v2 06/21] mm: thp: handle split failure in wp_huge_pmd() Usama Arif
2026-02-26 11:23 ` [RFC v2 07/21] mm: thp: retry on split failure in change_pmd_range() Usama Arif
2026-02-26 11:23 ` [RFC v2 08/21] mm: thp: handle split failure in follow_pmd_mask() Usama Arif
2026-02-26 11:23 ` [RFC v2 09/21] mm: handle walk_page_range() failure from THP split Usama Arif
2026-02-26 11:23 ` [RFC v2 10/21] mm: thp: handle split failure in mremap move_page_tables() Usama Arif
2026-02-26 11:23 ` [RFC v2 11/21] mm: thp: handle split failure in userfaultfd move_pages() Usama Arif
2026-02-26 11:23 ` [RFC v2 12/21] mm: thp: handle split failure in device migration Usama Arif
2026-02-26 11:23 ` [RFC v2 13/21] mm: huge_mm: Make sure all split_huge_pmd calls are checked Usama Arif
2026-02-26 11:23 ` [RFC v2 14/21] mm: thp: allocate PTE page tables lazily at split time Usama Arif
2026-02-26 11:23 ` [RFC v2 15/21] mm: thp: remove pgtable_trans_huge_{deposit/withdraw} when not needed Usama Arif
2026-02-26 11:23 ` [RFC v2 16/21] mm: thp: add THP_SPLIT_PMD_FAILED counter Usama Arif
2026-02-26 14:22 ` Usama Arif [this message]
2026-02-26 11:23 ` [RFC v2 17/21] selftests/mm: add THP PMD split test infrastructure Usama Arif
2026-02-26 11:23 ` [RFC v2 18/21] selftests/mm: add partial_mprotect test for change_pmd_range Usama Arif
2026-02-26 11:23 ` [RFC v2 19/21] selftests/mm: add partial_mlock test Usama Arif
2026-02-26 11:23 ` [RFC v2 20/21] selftests/mm: add partial_mremap test for move_page_tables Usama Arif
2026-02-26 11:23 ` [RFC v2 21/21] selftests/mm: add madv_dontneed_partial test Usama Arif
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