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Date: Mon, 7 Dec 2020 19:31:20 +0800
From: yulei.kernel@...il.com
To: linux-mm@...ck.org, akpm@...ux-foundation.org,
linux-fsdevel@...r.kernel.org, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, naoya.horiguchi@....com,
viro@...iv.linux.org.uk, pbonzini@...hat.com
Cc: joao.m.martins@...cle.com, rdunlap@...radead.org,
sean.j.christopherson@...el.com, xiaoguangrong.eric@...il.com,
kernellwp@...il.com, lihaiwei.kernel@...il.com,
Yulei Zhang <yuleixzhang@...cent.com>,
Chen Zhuo <sagazchen@...cent.com>
Subject: [RFC V2 27/37] mm: add pud_special() check to support dmem huge pud
From: Yulei Zhang <yuleixzhang@...cent.com>
Add pud_special() and follow_special_pud() to support dmem
huge pud as we do for dmem huge pmd.
Signed-off-by: Chen Zhuo <sagazchen@...cent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@...cent.com>
---
arch/x86/include/asm/pgtable.h | 2 +-
include/linux/huge_mm.h | 2 +-
mm/gup.c | 46 ++++++++++++++++++++++++++++++++++++++++++
mm/huge_memory.c | 11 ++++++----
mm/memory.c | 4 ++--
mm/mprotect.c | 2 ++
mm/pagewalk.c | 2 +-
7 files changed, 60 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 9e36d42..2284387 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -265,7 +265,7 @@ static inline int pmd_trans_huge(pmd_t pmd)
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static inline int pud_trans_huge(pud_t pud)
{
- return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
+ return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP|_PAGE_DMEM)) == _PAGE_PSE;
}
#endif
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 2514b90..b69c940 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -251,7 +251,7 @@ static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
static inline spinlock_t *pud_trans_huge_lock(pud_t *pud,
struct vm_area_struct *vma)
{
- if (pud_trans_huge(*pud) || pud_devmap(*pud))
+ if (pud_trans_huge(*pud) || pud_devmap(*pud) || pud_special(*pud))
return __pud_trans_huge_lock(pud, vma);
else
return NULL;
diff --git a/mm/gup.c b/mm/gup.c
index 0ea9071..8eb85ba 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -423,6 +423,42 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
return ERR_PTR(-EEXIST);
}
+static struct page *
+follow_special_pud(struct vm_area_struct *vma, unsigned long address,
+ pud_t *pud, unsigned int flags)
+{
+ spinlock_t *ptl;
+
+ if ((flags & FOLL_DUMP) && is_huge_zero_pud(*pud))
+ /* Avoid special (like zero) pages in core dumps */
+ return ERR_PTR(-EFAULT);
+
+ /* No page to get reference */
+ if (flags & FOLL_GET)
+ return ERR_PTR(-EFAULT);
+
+ if (flags & FOLL_TOUCH) {
+ pud_t _pud;
+
+ ptl = pud_lock(vma->vm_mm, pud);
+ if (!pud_special(*pud)) {
+ spin_unlock(ptl);
+ return NULL;
+ }
+ _pud = pud_mkyoung(*pud);
+ if (flags & FOLL_WRITE)
+ _pud = pud_mkdirty(_pud);
+ if (pudp_set_access_flags(vma, address & HPAGE_PMD_MASK,
+ pud, _pud,
+ flags & FOLL_WRITE))
+ update_mmu_cache_pud(vma, address, pud);
+ spin_unlock(ptl);
+ }
+
+ /* Proper page table entry exists, but no corresponding struct page */
+ return ERR_PTR(-EEXIST);
+}
+
/*
* FOLL_FORCE can write to even unwritable pte's, but only
* after we've gone through a COW cycle and they are dirty.
@@ -726,6 +762,12 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma,
return page;
return no_page_table(vma, flags);
}
+ if (pud_special(*pud)) {
+ page = follow_special_pud(vma, address, pud, flags);
+ if (page)
+ return page;
+ return no_page_table(vma, flags);
+ }
if (is_hugepd(__hugepd(pud_val(*pud)))) {
page = follow_huge_pd(vma, address,
__hugepd(pud_val(*pud)), flags,
@@ -2511,6 +2553,10 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
if (!pud_access_permitted(orig, flags & FOLL_WRITE))
return 0;
+ /* Bypass dmem pud. It will be handled in outside routine. */
+ if (pud_special(orig))
+ return 0;
+
if (pud_devmap(orig)) {
if (unlikely(flags & FOLL_LONGTERM))
return 0;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6e52d57..7c5385a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -883,6 +883,8 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
entry = pud_mkhuge(pfn_t_pud(pfn, prot));
if (pfn_t_devmap(pfn))
entry = pud_mkdevmap(entry);
+ if (pfn_t_dmem(pfn))
+ entry = pud_mkdmem(entry);
if (write) {
entry = pud_mkyoung(pud_mkdirty(entry));
entry = maybe_pud_mkwrite(entry, vma);
@@ -919,7 +921,7 @@ vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
* can't support a 'special' bit.
*/
BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
- !pfn_t_devmap(pfn));
+ !pfn_t_devmap(pfn) && !pfn_t_dmem(pfn));
BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
(VM_PFNMAP|VM_MIXEDMAP));
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
@@ -1911,7 +1913,7 @@ spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
spinlock_t *ptl;
ptl = pud_lock(vma->vm_mm, pud);
- if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
+ if (likely(pud_trans_huge(*pud) || pud_devmap(*pud) || pud_special(*pud)))
return ptl;
spin_unlock(ptl);
return NULL;
@@ -1922,6 +1924,7 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
pud_t *pud, unsigned long addr)
{
spinlock_t *ptl;
+ pud_t orig_pud;
ptl = __pud_trans_huge_lock(pud, vma);
if (!ptl)
@@ -1932,9 +1935,9 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
* pgtable_trans_huge_withdraw after finishing pudp related
* operations.
*/
- pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
+ orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
tlb_remove_pud_tlb_entry(tlb, pud, addr);
- if (vma_is_special_huge(vma)) {
+ if (vma_is_special_huge(vma) || pud_special(orig_pud)) {
spin_unlock(ptl);
/* No zero page support yet */
} else {
diff --git a/mm/memory.c b/mm/memory.c
index abb9148..01f3b05 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1078,7 +1078,7 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
src_pud = pud_offset(src_p4d, addr);
do {
next = pud_addr_end(addr, end);
- if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
+ if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud) || pud_special(*src_pud)) {
int err;
VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
@@ -1375,7 +1375,7 @@ static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
pud = pud_offset(p4d, addr);
do {
next = pud_addr_end(addr, end);
- if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
+ if (pud_trans_huge(*pud) || pud_devmap(*pud) || pud_special(*pud)) {
if (next - addr != HPAGE_PUD_SIZE) {
mmap_assert_locked(tlb->mm);
split_huge_pud(vma, pud, addr);
diff --git a/mm/mprotect.c b/mm/mprotect.c
index b1650b5..05fa453 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -292,6 +292,8 @@ static inline unsigned long change_pud_range(struct vm_area_struct *vma,
pud = pud_offset(p4d, addr);
do {
next = pud_addr_end(addr, end);
+ if (pud_special(*pud))
+ continue;
if (pud_none_or_clear_bad(pud))
continue;
pages += change_pmd_range(vma, pud, addr, next, newprot,
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index e7c4575..afd8bca 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -129,7 +129,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
do {
again:
next = pud_addr_end(addr, end);
- if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) {
+ if (pud_none(*pud) || (!walk->vma && !walk->no_vma) || pud_special(*pud)) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, depth, walk);
if (err)
--
1.8.3.1
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