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* [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating
@ 2022-05-10  3:45 Baolin Wang
  2022-05-10  3:45 ` [PATCH v3 1/3] mm: change huge_ptep_clear_flush() to return the original pte Baolin Wang
                   ` (3 more replies)
  0 siblings, 4 replies; 11+ messages in thread
From: Baolin Wang @ 2022-05-10  3:45 UTC (permalink / raw)
  To: akpm, mike.kravetz, catalin.marinas, will
  Cc: songmuchun, tsbogend, James.Bottomley, deller, mpe, benh, paulus,
	hca, gor, agordeev, borntraeger, svens, ysato, dalias, davem,
	arnd, baolin.wang, linux-arm-kernel, linux-kernel, linux-ia64,
	linux-mips, linux-parisc, linuxppc-dev, linux-s390, linux-sh,
	sparclinux, linux-arch, linux-mm

Hi,

Now migrating a hugetlb page or unmapping a poisoned hugetlb page, we'll
use ptep_clear_flush() and set_pte_at() to nuke the page table entry
and remap it, and this is incorrect for CONT-PTE or CONT-PMD size hugetlb
page, which will cause potential data consistent issue. This patch set
will change to use hugetlb related APIs to fix this issue, please find
details in each patch. Thanks.

Note: Mike pointed out the huge_ptep_get() will only return the one specific
value, and it would not take into account the dirty or young bits of CONT-PTE/PMDs
like the huge_ptep_get_and_clear() [1]. This inconsistent issue is not introduced
by this patch set, and will address this issue in another thread [2]. Meanwhile
the uffd for hugetlb case [3] pointed by Gerald also need another patch to address.

[1] https://lore.kernel.org/linux-mm/85bd80b4-b4fd-0d3f-a2e5-149559f2f387@oracle.com/
[2] https://lore.kernel.org/all/cover.1651998586.git.baolin.wang@linux.alibaba.com/
[3] https://lore.kernel.org/linux-mm/20220503120343.6264e126@thinkpad/

Changes from v2:
 - Collect reviewed tags from Muchun and Mike.
 - Drop the unnecessary casting in hugetlb.c.
 - Fix building errors with adding dummy functions for !CONFIG_HUGETLB_PAGE.

Changes from v1:
 - Add acked tag from Mike.
 - Update some commit message.
 - Add VM_BUG_ON in try_to_unmap() for hugetlb case.
 - Add an explict void casting for huge_ptep_clear_flush() in hugetlb.c.

Baolin Wang (3):
  mm: change huge_ptep_clear_flush() to return the original pte
  mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
  mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping

 arch/arm64/include/asm/hugetlb.h   |  4 +--
 arch/arm64/mm/hugetlbpage.c        | 12 +++-----
 arch/ia64/include/asm/hugetlb.h    |  4 +--
 arch/mips/include/asm/hugetlb.h    |  9 ++++--
 arch/parisc/include/asm/hugetlb.h  |  4 +--
 arch/powerpc/include/asm/hugetlb.h |  9 ++++--
 arch/s390/include/asm/hugetlb.h    |  6 ++--
 arch/sh/include/asm/hugetlb.h      |  4 +--
 arch/sparc/include/asm/hugetlb.h   |  4 +--
 include/asm-generic/hugetlb.h      |  4 +--
 include/linux/hugetlb.h            | 11 +++++++
 mm/rmap.c                          | 63 ++++++++++++++++++++++++--------------
 12 files changed, 83 insertions(+), 51 deletions(-)

-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH v3 1/3] mm: change huge_ptep_clear_flush() to return the original pte
  2022-05-10  3:45 [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Baolin Wang
@ 2022-05-10  3:45 ` Baolin Wang
  2022-05-10  3:45 ` [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Baolin Wang
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 11+ messages in thread
From: Baolin Wang @ 2022-05-10  3:45 UTC (permalink / raw)
  To: akpm, mike.kravetz, catalin.marinas, will
  Cc: songmuchun, tsbogend, James.Bottomley, deller, mpe, benh, paulus,
	hca, gor, agordeev, borntraeger, svens, ysato, dalias, davem,
	arnd, baolin.wang, linux-arm-kernel, linux-kernel, linux-ia64,
	linux-mips, linux-parisc, linuxppc-dev, linux-s390, linux-sh,
	sparclinux, linux-arch, linux-mm

It is incorrect to use ptep_clear_flush() to nuke a hugetlb page
table when unmapping or migrating a hugetlb page, and will change
to use huge_ptep_clear_flush() instead in the following patches.

So this is a preparation patch, which changes the huge_ptep_clear_flush()
to return the original pte to help to nuke a hugetlb page table.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
---
 arch/arm64/include/asm/hugetlb.h   |  4 ++--
 arch/arm64/mm/hugetlbpage.c        | 12 +++++-------
 arch/ia64/include/asm/hugetlb.h    |  4 ++--
 arch/mips/include/asm/hugetlb.h    |  9 ++++++---
 arch/parisc/include/asm/hugetlb.h  |  4 ++--
 arch/powerpc/include/asm/hugetlb.h |  9 ++++++---
 arch/s390/include/asm/hugetlb.h    |  6 +++---
 arch/sh/include/asm/hugetlb.h      |  4 ++--
 arch/sparc/include/asm/hugetlb.h   |  4 ++--
 include/asm-generic/hugetlb.h      |  4 ++--
 10 files changed, 32 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index 1242f71..616b2ca 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -39,8 +39,8 @@ extern pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 extern void huge_ptep_set_wrprotect(struct mm_struct *mm,
 				    unsigned long addr, pte_t *ptep);
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-extern void huge_ptep_clear_flush(struct vm_area_struct *vma,
-				  unsigned long addr, pte_t *ptep);
+extern pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+				   unsigned long addr, pte_t *ptep);
 #define __HAVE_ARCH_HUGE_PTE_CLEAR
 extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 			   pte_t *ptep, unsigned long sz);
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index cbace1c..ca8e65c 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -486,19 +486,17 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
 		set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
 }
 
-void huge_ptep_clear_flush(struct vm_area_struct *vma,
-			   unsigned long addr, pte_t *ptep)
+pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+			    unsigned long addr, pte_t *ptep)
 {
 	size_t pgsize;
 	int ncontig;
 
-	if (!pte_cont(READ_ONCE(*ptep))) {
-		ptep_clear_flush(vma, addr, ptep);
-		return;
-	}
+	if (!pte_cont(READ_ONCE(*ptep)))
+		return ptep_clear_flush(vma, addr, ptep);
 
 	ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
-	clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
+	return get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
 }
 
 static int __init hugetlbpage_init(void)
diff --git a/arch/ia64/include/asm/hugetlb.h b/arch/ia64/include/asm/hugetlb.h
index 7e46ebd..65d3811 100644
--- a/arch/ia64/include/asm/hugetlb.h
+++ b/arch/ia64/include/asm/hugetlb.h
@@ -23,8 +23,8 @@ static inline int is_hugepage_only_range(struct mm_struct *mm,
 #define is_hugepage_only_range is_hugepage_only_range
 
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long addr, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h
index c214440..fd69c88 100644
--- a/arch/mips/include/asm/hugetlb.h
+++ b/arch/mips/include/asm/hugetlb.h
@@ -43,16 +43,19 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 }
 
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long addr, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
+	pte_t pte;
+
 	/*
 	 * clear the huge pte entry firstly, so that the other smp threads will
 	 * not get old pte entry after finishing flush_tlb_page and before
 	 * setting new huge pte entry
 	 */
-	huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
+	pte = huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
 	flush_tlb_page(vma, addr);
+	return pte;
 }
 
 #define __HAVE_ARCH_HUGE_PTE_NONE
diff --git a/arch/parisc/include/asm/hugetlb.h b/arch/parisc/include/asm/hugetlb.h
index a69cf9e..25bc560 100644
--- a/arch/parisc/include/asm/hugetlb.h
+++ b/arch/parisc/include/asm/hugetlb.h
@@ -28,8 +28,8 @@ static inline int prepare_hugepage_range(struct file *file,
 }
 
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long addr, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index 6a1a1ac..8a5674f 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -43,11 +43,14 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 }
 
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long addr, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
-	huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
+	pte_t pte;
+
+	pte = huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
 	flush_hugetlb_page(vma, addr);
+	return pte;
 }
 
 #define __HAVE_ARCH_HUGE_PTEP_SET_ACCESS_FLAGS
diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index 32c3fd6..f22beda 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -50,10 +50,10 @@ static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 		set_pte(ptep, __pte(_SEGMENT_ENTRY_EMPTY));
 }
 
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long address, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long address, pte_t *ptep)
 {
-	huge_ptep_get_and_clear(vma->vm_mm, address, ptep);
+	return huge_ptep_get_and_clear(vma->vm_mm, address, ptep);
 }
 
 static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
diff --git a/arch/sh/include/asm/hugetlb.h b/arch/sh/include/asm/hugetlb.h
index ae4de7b..e727cc9 100644
--- a/arch/sh/include/asm/hugetlb.h
+++ b/arch/sh/include/asm/hugetlb.h
@@ -21,8 +21,8 @@ static inline int prepare_hugepage_range(struct file *file,
 }
 
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long addr, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h
index 53838a1..b50aa6f 100644
--- a/arch/sparc/include/asm/hugetlb.h
+++ b/arch/sparc/include/asm/hugetlb.h
@@ -21,8 +21,8 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep);
 
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long addr, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 896f341..a57d667 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -84,10 +84,10 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 #endif
 
 #ifndef __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
 		unsigned long addr, pte_t *ptep)
 {
-	ptep_clear_flush(vma, addr, ptep);
+	return ptep_clear_flush(vma, addr, ptep);
 }
 #endif
 
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread

* [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
  2022-05-10  3:45 [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Baolin Wang
  2022-05-10  3:45 ` [PATCH v3 1/3] mm: change huge_ptep_clear_flush() to return the original pte Baolin Wang
@ 2022-05-10  3:45 ` Baolin Wang
  2022-05-10 23:17   ` Andrew Morton
  2022-05-11  1:19   ` kernel test robot
  2022-05-10  3:46 ` [PATCH v3 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Baolin Wang
  2022-05-10  4:04 ` [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Andrew Morton
  3 siblings, 2 replies; 11+ messages in thread
From: Baolin Wang @ 2022-05-10  3:45 UTC (permalink / raw)
  To: akpm, mike.kravetz, catalin.marinas, will
  Cc: songmuchun, tsbogend, James.Bottomley, deller, mpe, benh, paulus,
	hca, gor, agordeev, borntraeger, svens, ysato, dalias, davem,
	arnd, baolin.wang, linux-arm-kernel, linux-kernel, linux-ia64,
	linux-mips, linux-parisc, linuxppc-dev, linux-s390, linux-sh,
	sparclinux, linux-arch, linux-mm

On some architectures (like ARM64), it can support CONT-PTE/PMD size
hugetlb, which means it can support not only PMD/PUD size hugetlb:
2M and 1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page
size specified.

When migrating a hugetlb page, we will get the relevant page table
entry by huge_pte_offset() only once to nuke it and remap it with
a migration pte entry. This is correct for PMD or PUD size hugetlb,
since they always contain only one pmd entry or pud entry in the
page table.

However this is incorrect for CONT-PTE and CONT-PMD size hugetlb,
since they can contain several continuous pte or pmd entry with
same page table attributes. So we will nuke or remap only one pte
or pmd entry for this CONT-PTE/PMD size hugetlb page, which is
not expected for hugetlb migration. The problem is we can still
continue to modify the subpages' data of a hugetlb page during
migrating a hugetlb page, which can cause a serious data consistent
issue, since we did not nuke the page table entry and set a
migration pte for the subpages of a hugetlb page.

To fix this issue, we should change to use huge_ptep_clear_flush()
to nuke a hugetlb page table, and remap it with set_huge_pte_at()
and set_huge_swap_pte_at() when migrating a hugetlb page, which
already considered the CONT-PTE or CONT-PMD size hugetlb.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 include/linux/hugetlb.h | 11 +++++++++++
 mm/rmap.c               | 24 ++++++++++++++++++------
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 306d6ef..9f71043 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -1093,6 +1093,17 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr
 					pte_t *ptep, pte_t pte, unsigned long sz)
 {
 }
+
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
+{
+	return ptep_get(ptep);
+}
+
+static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
+				   pte_t *ptep, pte_t pte)
+{
+}
 #endif	/* CONFIG_HUGETLB_PAGE */
 
 static inline spinlock_t *huge_pte_lock(struct hstate *h,
diff --git a/mm/rmap.c b/mm/rmap.c
index 94d6b24..4e96daf 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1926,13 +1926,15 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 					break;
 				}
 			}
+
+			/* Nuke the hugetlb page table entry */
+			pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
 		} else {
 			flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
+			/* Nuke the page table entry. */
+			pteval = ptep_clear_flush(vma, address, pvmw.pte);
 		}
 
-		/* Nuke the page table entry. */
-		pteval = ptep_clear_flush(vma, address, pvmw.pte);
-
 		/* Set the dirty flag on the folio now the pte is gone. */
 		if (pte_dirty(pteval))
 			folio_mark_dirty(folio);
@@ -2017,7 +2019,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 			pte_t swp_pte;
 
 			if (arch_unmap_one(mm, vma, address, pteval) < 0) {
-				set_pte_at(mm, address, pvmw.pte, pteval);
+				if (folio_test_hugetlb(folio))
+					set_huge_pte_at(mm, address, pvmw.pte, pteval);
+				else
+					set_pte_at(mm, address, pvmw.pte, pteval);
 				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
@@ -2026,7 +2031,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 				       !anon_exclusive, subpage);
 			if (anon_exclusive &&
 			    page_try_share_anon_rmap(subpage)) {
-				set_pte_at(mm, address, pvmw.pte, pteval);
+				if (folio_test_hugetlb(folio))
+					set_huge_pte_at(mm, address, pvmw.pte, pteval);
+				else
+					set_pte_at(mm, address, pvmw.pte, pteval);
 				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
@@ -2052,7 +2060,11 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 				swp_pte = pte_swp_mksoft_dirty(swp_pte);
 			if (pte_uffd_wp(pteval))
 				swp_pte = pte_swp_mkuffd_wp(swp_pte);
-			set_pte_at(mm, address, pvmw.pte, swp_pte);
+			if (folio_test_hugetlb(folio))
+				set_huge_swap_pte_at(mm, address, pvmw.pte,
+						     swp_pte, vma_mmu_pagesize(vma));
+			else
+				set_pte_at(mm, address, pvmw.pte, swp_pte);
 			trace_set_migration_pte(address, pte_val(swp_pte),
 						compound_order(&folio->page));
 			/*
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread

* [PATCH v3 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping
  2022-05-10  3:45 [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Baolin Wang
  2022-05-10  3:45 ` [PATCH v3 1/3] mm: change huge_ptep_clear_flush() to return the original pte Baolin Wang
  2022-05-10  3:45 ` [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Baolin Wang
@ 2022-05-10  3:46 ` Baolin Wang
  2022-05-10  4:04 ` [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Andrew Morton
  3 siblings, 0 replies; 11+ messages in thread
From: Baolin Wang @ 2022-05-10  3:46 UTC (permalink / raw)
  To: akpm, mike.kravetz, catalin.marinas, will
  Cc: songmuchun, tsbogend, James.Bottomley, deller, mpe, benh, paulus,
	hca, gor, agordeev, borntraeger, svens, ysato, dalias, davem,
	arnd, baolin.wang, linux-arm-kernel, linux-kernel, linux-ia64,
	linux-mips, linux-parisc, linuxppc-dev, linux-s390, linux-sh,
	sparclinux, linux-arch, linux-mm

On some architectures (like ARM64), it can support CONT-PTE/PMD size
hugetlb, which means it can support not only PMD/PUD size hugetlb:
2M and 1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page
size specified.

When unmapping a hugetlb page, we will get the relevant page table
entry by huge_pte_offset() only once to nuke it. This is correct
for PMD or PUD size hugetlb, since they always contain only one
pmd entry or pud entry in the page table.

However this is incorrect for CONT-PTE and CONT-PMD size hugetlb,
since they can contain several continuous pte or pmd entry with
same page table attributes, so we will nuke only one pte or pmd
entry for this CONT-PTE/PMD size hugetlb page.

And now try_to_unmap() is only passed a hugetlb page in the case
where the hugetlb page is poisoned. Which means now we will unmap
only one pte entry for a CONT-PTE or CONT-PMD size poisoned hugetlb
page, and we can still access other subpages of a CONT-PTE or CONT-PMD
size poisoned hugetlb page, which will cause serious issues possibly.

So we should change to use huge_ptep_clear_flush() to nuke the
hugetlb page table to fix this issue, which already considered
CONT-PTE and CONT-PMD size hugetlb.

We've already used set_huge_swap_pte_at() to set a poisoned
swap entry for a poisoned hugetlb page. Meanwhile adding a VM_BUG_ON()
to make sure the passed hugetlb page is poisoned in try_to_unmap().

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 mm/rmap.c | 39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 4e96daf..219e287 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1528,6 +1528,11 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 
 		if (folio_test_hugetlb(folio)) {
 			/*
+			 * The try_to_unmap() is only passed a hugetlb page
+			 * in the case where the hugetlb page is poisoned.
+			 */
+			VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage);
+			/*
 			 * huge_pmd_unshare may unmap an entire PMD page.
 			 * There is no way of knowing exactly which PMDs may
 			 * be cached for this mm, so we must flush them all.
@@ -1562,28 +1567,28 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 					break;
 				}
 			}
+			pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
 		} else {
 			flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
-		}
-
-		/*
-		 * Nuke the page table entry. When having to clear
-		 * PageAnonExclusive(), we always have to flush.
-		 */
-		if (should_defer_flush(mm, flags) && !anon_exclusive) {
 			/*
-			 * We clear the PTE but do not flush so potentially
-			 * a remote CPU could still be writing to the folio.
-			 * If the entry was previously clean then the
-			 * architecture must guarantee that a clear->dirty
-			 * transition on a cached TLB entry is written through
-			 * and traps if the PTE is unmapped.
+			 * Nuke the page table entry. When having to clear
+			 * PageAnonExclusive(), we always have to flush.
 			 */
-			pteval = ptep_get_and_clear(mm, address, pvmw.pte);
+			if (should_defer_flush(mm, flags) && !anon_exclusive) {
+				/*
+				 * We clear the PTE but do not flush so potentially
+				 * a remote CPU could still be writing to the folio.
+				 * If the entry was previously clean then the
+				 * architecture must guarantee that a clear->dirty
+				 * transition on a cached TLB entry is written through
+				 * and traps if the PTE is unmapped.
+				 */
+				pteval = ptep_get_and_clear(mm, address, pvmw.pte);
 
-			set_tlb_ubc_flush_pending(mm, pte_dirty(pteval));
-		} else {
-			pteval = ptep_clear_flush(vma, address, pvmw.pte);
+				set_tlb_ubc_flush_pending(mm, pte_dirty(pteval));
+			} else {
+				pteval = ptep_clear_flush(vma, address, pvmw.pte);
+			}
 		}
 
 		/*
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread

* Re: [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating
  2022-05-10  3:45 [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Baolin Wang
                   ` (2 preceding siblings ...)
  2022-05-10  3:46 ` [PATCH v3 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Baolin Wang
@ 2022-05-10  4:04 ` Andrew Morton
  2022-05-10  4:26   ` Baolin Wang
  3 siblings, 1 reply; 11+ messages in thread
From: Andrew Morton @ 2022-05-10  4:04 UTC (permalink / raw)
  To: Baolin Wang
  Cc: mike.kravetz, catalin.marinas, will, songmuchun, tsbogend,
	James.Bottomley, deller, mpe, benh, paulus, hca, gor, agordeev,
	borntraeger, svens, ysato, dalias, davem, arnd, linux-arm-kernel,
	linux-kernel, linux-ia64, linux-mips, linux-parisc, linuxppc-dev,
	linux-s390, linux-sh, sparclinux, linux-arch, linux-mm

On Tue, 10 May 2022 11:45:57 +0800 Baolin Wang <baolin.wang@linux.alibaba.com> wrote:

> Hi,
> 
> Now migrating a hugetlb page or unmapping a poisoned hugetlb page, we'll
> use ptep_clear_flush() and set_pte_at() to nuke the page table entry
> and remap it, and this is incorrect for CONT-PTE or CONT-PMD size hugetlb
> page,

It would be helpful to describe why it's wrong.  Something like "should
use huge_ptep_clear_flush() and huge_ptep_clear_flush() for this
purpose"?

> which will cause potential data consistent issue. This patch set
> will change to use hugetlb related APIs to fix this issue, please find
> details in each patch. Thanks.

Is a cc:stable needed here?  And are we able to identify a target for a
Fixes: tag?



^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating
  2022-05-10  4:04 ` [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Andrew Morton
@ 2022-05-10  4:26   ` Baolin Wang
  0 siblings, 0 replies; 11+ messages in thread
From: Baolin Wang @ 2022-05-10  4:26 UTC (permalink / raw)
  To: Andrew Morton
  Cc: mike.kravetz, catalin.marinas, will, songmuchun, tsbogend,
	James.Bottomley, deller, mpe, benh, paulus, hca, gor, agordeev,
	borntraeger, svens, ysato, dalias, davem, arnd, linux-arm-kernel,
	linux-kernel, linux-ia64, linux-mips, linux-parisc, linuxppc-dev,
	linux-s390, linux-sh, sparclinux, linux-arch, linux-mm



On 5/10/2022 12:04 PM, Andrew Morton wrote:
> On Tue, 10 May 2022 11:45:57 +0800 Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> 
>> Hi,
>>
>> Now migrating a hugetlb page or unmapping a poisoned hugetlb page, we'll
>> use ptep_clear_flush() and set_pte_at() to nuke the page table entry
>> and remap it, and this is incorrect for CONT-PTE or CONT-PMD size hugetlb
>> page,
> 
> It would be helpful to describe why it's wrong.  Something like "should
> use huge_ptep_clear_flush() and huge_ptep_clear_flush() for this
> purpose"?

Sorry for the confusing description. I described the problem explicitly 
in each patch's commit message.

https://lore.kernel.org/all/ea5abf529f0997b5430961012bfda6166c1efc8c.1652147571.git.baolin.wang@linux.alibaba.com/
https://lore.kernel.org/all/730ea4b6d292f32fb10b7a4e87dad49b0eb30474.1652147571.git.baolin.wang@linux.alibaba.com/

> 
>> which will cause potential data consistent issue. This patch set
>> will change to use hugetlb related APIs to fix this issue, please find
>> details in each patch. Thanks.
> 
> Is a cc:stable needed here?  And are we able to identify a target for a
> Fixes: tag?

I think need a cc:stable tag, however I am not sure the target fixes 
tag, since we should trace back to the introduction of CONT-PTE/PMD 
hugetlb? 66b3923a1a0f ("arm64: hugetlb: add support for PTE contiguous bit")

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
  2022-05-10  3:45 ` [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Baolin Wang
@ 2022-05-10 23:17   ` Andrew Morton
  2022-05-10 23:28     ` Andrew Morton
  2022-05-11  1:19   ` kernel test robot
  1 sibling, 1 reply; 11+ messages in thread
From: Andrew Morton @ 2022-05-10 23:17 UTC (permalink / raw)
  To: Baolin Wang
  Cc: mike.kravetz, catalin.marinas, will, songmuchun, tsbogend,
	James.Bottomley, deller, mpe, benh, paulus, hca, gor, agordeev,
	borntraeger, svens, ysato, dalias, davem, arnd, linux-arm-kernel,
	linux-kernel, linux-ia64, linux-mips, linux-parisc, linuxppc-dev,
	linux-s390, linux-sh, sparclinux, linux-arch, linux-mm

On Tue, 10 May 2022 11:45:59 +0800 Baolin Wang <baolin.wang@linux.alibaba.com> wrote:

> On some architectures (like ARM64), it can support CONT-PTE/PMD size
> hugetlb, which means it can support not only PMD/PUD size hugetlb:
> 2M and 1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page
> size specified.
> 
> When migrating a hugetlb page, we will get the relevant page table
> entry by huge_pte_offset() only once to nuke it and remap it with
> a migration pte entry. This is correct for PMD or PUD size hugetlb,
> since they always contain only one pmd entry or pud entry in the
> page table.
> 
> However this is incorrect for CONT-PTE and CONT-PMD size hugetlb,
> since they can contain several continuous pte or pmd entry with
> same page table attributes. So we will nuke or remap only one pte
> or pmd entry for this CONT-PTE/PMD size hugetlb page, which is
> not expected for hugetlb migration. The problem is we can still
> continue to modify the subpages' data of a hugetlb page during
> migrating a hugetlb page, which can cause a serious data consistent
> issue, since we did not nuke the page table entry and set a
> migration pte for the subpages of a hugetlb page.
> 
> To fix this issue, we should change to use huge_ptep_clear_flush()
> to nuke a hugetlb page table, and remap it with set_huge_pte_at()
> and set_huge_swap_pte_at() when migrating a hugetlb page, which
> already considered the CONT-PTE or CONT-PMD size hugetlb.
> 
> ...
>
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -1093,6 +1093,17 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr
>  					pte_t *ptep, pte_t pte, unsigned long sz)
>  {
>  }
> +
> +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
> +					  unsigned long addr, pte_t *ptep)
> +{
> +	return ptep_get(ptep);
> +}
> +
> +static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
> +				   pte_t *ptep, pte_t pte)
> +{
> +}
>  #endif	/* CONFIG_HUGETLB_PAGE */
>  

This blows up nommu (arm allnoconfig):

In file included from fs/io_uring.c:71:
./include/linux/hugetlb.h: In function 'huge_ptep_clear_flush':
./include/linux/hugetlb.h:1100:16: error: implicit declaration of function 'ptep_get' [-Werror=implicit-function-declaration]
 1100 |         return ptep_get(ptep);
      |                ^~~~~~~~


huge_ptep_clear_flush() is only used in CONFIG_NOMMU=n files, so I simply
zapped this change.

--- a/include/linux/hugetlb.h~mm-rmap-fix-cont-pte-pmd-size-hugetlb-issue-when-migration-fix
+++ a/include/linux/hugetlb.h
@@ -1093,17 +1093,6 @@ static inline void set_huge_swap_pte_at(
 					pte_t *ptep, pte_t pte, unsigned long sz)
 {
 }
-
-static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
-					  unsigned long addr, pte_t *ptep)
-{
-	return ptep_get(ptep);
-}
-
-static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
-				   pte_t *ptep, pte_t pte)
-{
-}
 #endif	/* CONFIG_HUGETLB_PAGE */
 
 static inline spinlock_t *huge_pte_lock(struct hstate *h,
_


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
  2022-05-10 23:17   ` Andrew Morton
@ 2022-05-10 23:28     ` Andrew Morton
  2022-05-11  3:59       ` Baolin Wang
  0 siblings, 1 reply; 11+ messages in thread
From: Andrew Morton @ 2022-05-10 23:28 UTC (permalink / raw)
  To: Baolin Wang, mike.kravetz, catalin.marinas, will, songmuchun,
	tsbogend, James.Bottomley, deller, mpe, benh, paulus, hca, gor,
	agordeev, borntraeger, svens, ysato, dalias, davem, arnd,
	linux-arm-kernel, linux-kernel, linux-ia64, linux-mips,
	linux-parisc, linuxppc-dev, linux-s390, linux-sh, sparclinux,
	linux-arch, linux-mm

On Tue, 10 May 2022 16:17:39 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:

> > +
> > +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
> > +					  unsigned long addr, pte_t *ptep)
> > +{
> > +	return ptep_get(ptep);
> > +}
> > +
> > +static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
> > +				   pte_t *ptep, pte_t pte)
> > +{
> > +}
> >  #endif	/* CONFIG_HUGETLB_PAGE */
> >  
> 
> This blows up nommu (arm allnoconfig):
> 
> In file included from fs/io_uring.c:71:
> ./include/linux/hugetlb.h: In function 'huge_ptep_clear_flush':
> ./include/linux/hugetlb.h:1100:16: error: implicit declaration of function 'ptep_get' [-Werror=implicit-function-declaration]
>  1100 |         return ptep_get(ptep);
>       |                ^~~~~~~~
> 
> 
> huge_ptep_clear_flush() is only used in CONFIG_NOMMU=n files, so I simply
> zapped this change.
> 

Well that wasn't a great success.  Doing this instead.  It's pretty
nasty - something nicer would be nicer please.

--- a/include/linux/hugetlb.h~mm-rmap-fix-cont-pte-pmd-size-hugetlb-issue-when-migration-fix
+++ a/include/linux/hugetlb.h
@@ -1094,6 +1094,7 @@ static inline void set_huge_swap_pte_at(
 {
 }
 
+#ifdef CONFIG_MMU
 static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
 					  unsigned long addr, pte_t *ptep)
 {
@@ -1104,6 +1105,7 @@ static inline void set_huge_pte_at(struc
 				   pte_t *ptep, pte_t pte)
 {
 }
+#endif
 #endif	/* CONFIG_HUGETLB_PAGE */
 
 static inline spinlock_t *huge_pte_lock(struct hstate *h,
_


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
  2022-05-10  3:45 ` [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Baolin Wang
  2022-05-10 23:17   ` Andrew Morton
@ 2022-05-11  1:19   ` kernel test robot
  2022-05-11  2:04     ` Andrew Morton
  1 sibling, 1 reply; 11+ messages in thread
From: kernel test robot @ 2022-05-11  1:19 UTC (permalink / raw)
  To: Baolin Wang, akpm, mike.kravetz, catalin.marinas, will
  Cc: kbuild-all, songmuchun, tsbogend, James.Bottomley, deller, mpe,
	benh, paulus, hca, gor, agordeev, borntraeger, svens, ysato,
	dalias, davem, arnd, baolin.wang, linux-arm-kernel, linux-kernel,
	linux-ia64, linux-mips, linux-parisc, linuxppc-dev, linux-s390,
	linux-sh, sparclinux

Hi Baolin,

I love your patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]
[cannot apply to hnaz-mm/master arm64/for-next/core linus/master v5.18-rc6]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/Baolin-Wang/Fix-CONT-PTE-PMD-size-hugetlb-issue-when-unmapping-or-migrating/20220510-114753
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: h8300-buildonly-randconfig-r001-20220509 (https://download.01.org/0day-ci/archive/20220511/202205110919.CWIcIqYE-lkp@intel.com/config)
compiler: h8300-linux-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/b666792b4c5f9774c350977ff88837bafc36365a
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Baolin-Wang/Fix-CONT-PTE-PMD-size-hugetlb-issue-when-unmapping-or-migrating/20220510-114753
        git checkout b666792b4c5f9774c350977ff88837bafc36365a
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=h8300 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from kernel/fork.c:51:
   include/linux/hugetlb.h: In function 'huge_ptep_clear_flush':
>> include/linux/hugetlb.h:1100:16: error: implicit declaration of function 'ptep_get' [-Werror=implicit-function-declaration]
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~
>> include/linux/hugetlb.h:1100:16: error: incompatible types when returning type 'int' but 'pte_t' was expected
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~~~~~~~
   kernel/fork.c: At top level:
   kernel/fork.c:162:13: warning: no previous prototype for 'arch_release_task_struct' [-Wmissing-prototypes]
     162 | void __weak arch_release_task_struct(struct task_struct *tsk)
         |             ^~~~~~~~~~~~~~~~~~~~~~~~
   kernel/fork.c:847:20: warning: no previous prototype for 'arch_task_cache_init' [-Wmissing-prototypes]
     847 | void __init __weak arch_task_cache_init(void) { }
         |                    ^~~~~~~~~~~~~~~~~~~~
   kernel/fork.c:942:12: warning: no previous prototype for 'arch_dup_task_struct' [-Wmissing-prototypes]
     942 | int __weak arch_dup_task_struct(struct task_struct *dst,
         |            ^~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from kernel/sysctl.c:46:
   include/linux/hugetlb.h: In function 'huge_ptep_clear_flush':
>> include/linux/hugetlb.h:1100:16: error: implicit declaration of function 'ptep_get' [-Werror=implicit-function-declaration]
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~
>> include/linux/hugetlb.h:1100:16: error: incompatible types when returning type 'int' but 'pte_t' was expected
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from include/linux/migrate.h:8,
                    from mm/page_alloc.c:62:
   include/linux/hugetlb.h: In function 'huge_ptep_clear_flush':
>> include/linux/hugetlb.h:1100:16: error: implicit declaration of function 'ptep_get' [-Werror=implicit-function-declaration]
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~
>> include/linux/hugetlb.h:1100:16: error: incompatible types when returning type 'int' but 'pte_t' was expected
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~~~~~~~
   In file included from include/asm-generic/bug.h:5,
                    from arch/h8300/include/asm/bug.h:8,
                    from include/linux/bug.h:5,
                    from include/linux/mmdebug.h:5,
                    from include/linux/mm.h:6,
                    from mm/page_alloc.c:19:
   mm/page_alloc.c: In function 'free_pages':
   include/asm-generic/page.h:89:51: warning: ordered comparison of pointer with null pointer [-Wextra]
      89 | #define virt_addr_valid(kaddr)  (((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
         |                                                   ^~
   include/linux/compiler.h:78:45: note: in definition of macro 'unlikely'
      78 | # define unlikely(x)    __builtin_expect(!!(x), 0)
         |                                             ^
   include/linux/mmdebug.h:17:25: note: in expansion of macro 'BUG_ON'
      17 | #define VM_BUG_ON(cond) BUG_ON(cond)
         |                         ^~~~~~
   mm/page_alloc.c:5489:17: note: in expansion of macro 'VM_BUG_ON'
    5489 |                 VM_BUG_ON(!virt_addr_valid((void *)addr));
         |                 ^~~~~~~~~
   mm/page_alloc.c:5489:28: note: in expansion of macro 'virt_addr_valid'
    5489 |                 VM_BUG_ON(!virt_addr_valid((void *)addr));
         |                            ^~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from fs/io_uring.c:71:
   include/linux/hugetlb.h: In function 'huge_ptep_clear_flush':
>> include/linux/hugetlb.h:1100:16: error: implicit declaration of function 'ptep_get' [-Werror=implicit-function-declaration]
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~
>> include/linux/hugetlb.h:1100:16: error: incompatible types when returning type 'int' but 'pte_t' was expected
    1100 |         return ptep_get(ptep);
         |                ^~~~~~~~~~~~~~
   fs/io_uring.c: In function '__io_submit_flush_completions':
   fs/io_uring.c:2660:40: warning: variable 'prev' set but not used [-Wunused-but-set-variable]
    2660 |         struct io_wq_work_node *node, *prev;
         |                                        ^~~~
   cc1: some warnings being treated as errors


vim +/ptep_get +1100 include/linux/hugetlb.h

  1096	
  1097	static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
  1098						  unsigned long addr, pte_t *ptep)
  1099	{
> 1100		return ptep_get(ptep);
  1101	}
  1102	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
  2022-05-11  1:19   ` kernel test robot
@ 2022-05-11  2:04     ` Andrew Morton
  0 siblings, 0 replies; 11+ messages in thread
From: Andrew Morton @ 2022-05-11  2:04 UTC (permalink / raw)
  To: kernel test robot
  Cc: Baolin Wang, mike.kravetz, catalin.marinas, will, kbuild-all,
	songmuchun, tsbogend, James.Bottomley, deller, mpe, benh, paulus,
	hca, gor, agordeev, borntraeger, svens, ysato, dalias, davem,
	arnd, linux-arm-kernel, linux-kernel, linux-ia64, linux-mips,
	linux-parisc, linuxppc-dev, linux-s390, linux-sh, sparclinux

On Wed, 11 May 2022 09:19:17 +0800 kernel test robot <lkp@intel.com> wrote:

> Hi Baolin,
> 
> I love your patch! Yet something to improve:
> 
> [auto build test ERROR on akpm-mm/mm-everything]
> [cannot apply to hnaz-mm/master arm64/for-next/core linus/master v5.18-rc6]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Baolin-Wang/Fix-CONT-PTE-PMD-size-hugetlb-issue-when-unmapping-or-migrating/20220510-114753
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> config: h8300-buildonly-randconfig-r001-20220509 (https://download.01.org/0day-ci/archive/20220511/202205110919.CWIcIqYE-lkp@intel.com/config)
> compiler: h8300-linux-gcc (GCC) 11.3.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/intel-lab-lkp/linux/commit/b666792b4c5f9774c350977ff88837bafc36365a
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Baolin-Wang/Fix-CONT-PTE-PMD-size-hugetlb-issue-when-unmapping-or-migrating/20220510-114753
>         git checkout b666792b4c5f9774c350977ff88837bafc36365a
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=h8300 SHELL=/bin/bash
> 
> ...

Thanks. 
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-fix-cont-pte-pmd-size-hugetlb-issue-when-migration-fix.patch
(which is in current mm-everything) fixes this up.


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
  2022-05-10 23:28     ` Andrew Morton
@ 2022-05-11  3:59       ` Baolin Wang
  0 siblings, 0 replies; 11+ messages in thread
From: Baolin Wang @ 2022-05-11  3:59 UTC (permalink / raw)
  To: Andrew Morton, mike.kravetz, catalin.marinas, will, songmuchun,
	tsbogend, James.Bottomley, deller, mpe, benh, paulus, hca, gor,
	agordeev, borntraeger, svens, ysato, dalias, davem, arnd,
	linux-arm-kernel, linux-kernel, linux-ia64, linux-mips,
	linux-parisc, linuxppc-dev, linux-s390, linux-sh, sparclinux,
	linux-arch, linux-mm



On 5/11/2022 7:28 AM, Andrew Morton wrote:
> On Tue, 10 May 2022 16:17:39 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
> 
>>> +
>>> +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
>>> +					  unsigned long addr, pte_t *ptep)
>>> +{
>>> +	return ptep_get(ptep);
>>> +}
>>> +
>>> +static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
>>> +				   pte_t *ptep, pte_t pte)
>>> +{
>>> +}
>>>   #endif	/* CONFIG_HUGETLB_PAGE */
>>>   
>>
>> This blows up nommu (arm allnoconfig):
>>
>> In file included from fs/io_uring.c:71:
>> ./include/linux/hugetlb.h: In function 'huge_ptep_clear_flush':
>> ./include/linux/hugetlb.h:1100:16: error: implicit declaration of function 'ptep_get' [-Werror=implicit-function-declaration]
>>   1100 |         return ptep_get(ptep);
>>        |                ^~~~~~~~
>>
>>
>> huge_ptep_clear_flush() is only used in CONFIG_NOMMU=n files, so I simply
>> zapped this change.
>>
> 
> Well that wasn't a great success.  Doing this instead.  It's pretty
> nasty - something nicer would be nicer please.

Thanks for fixing the building issue. I'll look at this to simplify the 
dummy function. Myabe just remove the ptep_get().

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -1097,7 +1097,7 @@ static inline void set_huge_swap_pte_at(struct 
mm_struct *mm, unsigned long addr
  static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
                                           unsigned long addr, pte_t *ptep)
  {
-       return ptep_get(ptep);
+       return *ptep;
  }

> 
> --- a/include/linux/hugetlb.h~mm-rmap-fix-cont-pte-pmd-size-hugetlb-issue-when-migration-fix
> +++ a/include/linux/hugetlb.h
> @@ -1094,6 +1094,7 @@ static inline void set_huge_swap_pte_at(
>   {
>   }
>   
> +#ifdef CONFIG_MMU
>   static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
>   					  unsigned long addr, pte_t *ptep)
>   {
> @@ -1104,6 +1105,7 @@ static inline void set_huge_pte_at(struc
>   				   pte_t *ptep, pte_t pte)
>   {
>   }
> +#endif
>   #endif	/* CONFIG_HUGETLB_PAGE */
>   
>   static inline spinlock_t *huge_pte_lock(struct hstate *h,
> _

^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2022-05-11  3:59 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-10  3:45 [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Baolin Wang
2022-05-10  3:45 ` [PATCH v3 1/3] mm: change huge_ptep_clear_flush() to return the original pte Baolin Wang
2022-05-10  3:45 ` [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Baolin Wang
2022-05-10 23:17   ` Andrew Morton
2022-05-10 23:28     ` Andrew Morton
2022-05-11  3:59       ` Baolin Wang
2022-05-11  1:19   ` kernel test robot
2022-05-11  2:04     ` Andrew Morton
2022-05-10  3:46 ` [PATCH v3 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Baolin Wang
2022-05-10  4:04 ` [PATCH v3 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Andrew Morton
2022-05-10  4:26   ` Baolin Wang

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