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mm: change huge_ptep_clear_flush() to return the original pte

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Patch series "Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating", v4.

presently, 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.

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 this issue
will be addressed in another thread [2].  Meanwhile the uffd for hugetlb
case [3] pointed out by Gerald also needs 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/


This patch (of 3):

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.

[baolin.wang@linux.alibaba.com: fix build in several more architectures]
  Link: https://lkml.kernel.org/r/0009a4cd-2826-e8be-e671-f050d4f18d5d@linux.alibaba.com
[sfr@canb.auug.org.au: fixup]
  Link: https://lkml.kernel.org/r/20220511181531.7f27a5c1@canb.auug.org.au
Link: https://lkml.kernel.org/r/cover.1652270205.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20f77ddab90baa249bd24504c413189b82acde69.1652270205.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/cover.1652147571.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/dcf065868cce35bceaf138613ad27f17bb7c0c19.1652147571.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Cc: Rich Felker <dalias@libc.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baolin Wang 2022-05-13 16:48:55 -07:00 committed by Andrew Morton
parent 110bf7a523
commit ae07562909
10 changed files with 36 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/include/asm/hugetlb.h
View File

@ -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);

12
arch/arm64/mm/hugetlbpage.c
View File

@ -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)

5
arch/ia64/include/asm/hugetlb.h
View File

@ -23,9 +23,10 @@ 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)
{
return *ptep;
}
#include <asm-generic/hugetlb.h>

9
arch/mips/include/asm/hugetlb.h
View File

@ -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

5
arch/parisc/include/asm/hugetlb.h
View File

@ -28,9 +28,10 @@ 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)
{
return *ptep;
}
#define __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT

9
arch/powerpc/include/asm/hugetlb.h
View File

@ -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

6
arch/s390/include/asm/hugetlb.h
View File

@ -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,

5
arch/sh/include/asm/hugetlb.h
View File

@ -21,9 +21,10 @@ 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)
{
return *ptep;
}
static inline void arch_clear_hugepage_flags(struct page *page)

5
arch/sparc/include/asm/hugetlb.h
View File

@ -21,9 +21,10 @@ 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)
{
return *ptep;
}
#define __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT

4
include/asm-generic/hugetlb.h
View File

@ -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