[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-Id: <20241008061746.285961-3-dev.jain@arm.com>
Date: Tue, 8 Oct 2024 11:47:46 +0530
From: Dev Jain <dev.jain@....com>
To: akpm@...ux-foundation.org,
david@...hat.com,
willy@...radead.org,
kirill.shutemov@...ux.intel.com
Cc: ryan.roberts@....com,
anshuman.khandual@....com,
catalin.marinas@....com,
cl@...two.org,
vbabka@...e.cz,
mhocko@...e.com,
apopple@...dia.com,
dave.hansen@...ux.intel.com,
will@...nel.org,
baohua@...nel.org,
jack@...e.cz,
mark.rutland@....com,
hughd@...gle.com,
aneesh.kumar@...nel.org,
yang@...amperecomputing.com,
peterx@...hat.com,
ioworker0@...il.com,
jglisse@...gle.com,
wangkefeng.wang@...wei.com,
ziy@...dia.com,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
Dev Jain <dev.jain@....com>
Subject: [PATCH v7 2/2] mm: Allocate THP on hugezeropage wp-fault
Introduce do_huge_zero_wp_pmd() to handle wp-fault on a hugezeropage and
replace it with a PMD-mapped THP. Remember to flush TLB entry
corresponding to the hugezeropage. In case of failure, fallback
to splitting the PMD.
Acked-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@...wei.com>
Signed-off-by: Dev Jain <dev.jain@....com>
---
mm/huge_memory.c | 41 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e21c4f759e00..606ed782a15a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1790,6 +1790,38 @@ void huge_pmd_set_accessed(struct vm_fault *vmf)
spin_unlock(vmf->ptl);
}
+static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf)
+{
+ unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
+ struct vm_area_struct *vma = vmf->vma;
+ struct mmu_notifier_range range;
+ struct folio *folio;
+ vm_fault_t ret = 0;
+
+ folio = vma_alloc_anon_folio_pmd(vma, vmf->address);
+ if (unlikely(!folio))
+ return VM_FAULT_FALLBACK;
+
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, haddr,
+ haddr + HPAGE_PMD_SIZE);
+ mmu_notifier_invalidate_range_start(&range);
+ vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
+ if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd)))
+ goto release;
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ goto release;
+ (void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd);
+ map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
+ goto unlock;
+release:
+ folio_put(folio);
+unlock:
+ spin_unlock(vmf->ptl);
+ mmu_notifier_invalidate_range_end(&range);
+ return ret;
+}
+
vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
{
const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
@@ -1802,8 +1834,15 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
VM_BUG_ON_VMA(!vma->anon_vma, vma);
- if (is_huge_zero_pmd(orig_pmd))
+ if (is_huge_zero_pmd(orig_pmd)) {
+ vm_fault_t ret = do_huge_zero_wp_pmd(vmf);
+
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+
+ /* Fallback to splitting PMD if THP cannot be allocated */
goto fallback;
+ }
spin_lock(vmf->ptl);
--
2.30.2
Powered by blists - more mailing lists