linux-kernel - [RFC 03/11] khugepaged: Don't allocate khugepaged mm

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Message-ID: <20250108233128.14484-4-npache@redhat.com>
Date: Wed,  8 Jan 2025 16:31:19 -0700
From: Nico Pache <npache@...hat.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
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Subject: [RFC 03/11] khugepaged: Don't allocate khugepaged mm_slot early

We should only "enter"/allocate the khugepaged mm_slot if we succeed at
allocating the PMD sized folio. Move the khugepaged_enter_vma call until
after we know the vma_alloc_folio was successful.

Signed-off-by: Nico Pache <npache@...hat.com>
---
 mm/huge_memory.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e53d83b3e5cf..635c65e7ef63 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1323,7 +1323,6 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 	ret = vmf_anon_prepare(vmf);
 	if (ret)
 		return ret;
-	khugepaged_enter_vma(vma, vma->vm_flags);
 
 	if (!(vmf->flags & FAULT_FLAG_WRITE) &&
 			!mm_forbids_zeropage(vma->vm_mm) &&
@@ -1365,7 +1364,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 		}
 		return ret;
 	}
-
+	khugepaged_enter_vma(vma, vma->vm_flags);
 	return __do_huge_pmd_anonymous_page(vmf);
 }
 
-- 
2.47.1