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mm/mprotect: factor out check whether manual PTE write upgrades are required 

Let's factor the check out into vma_wants_manual_pte_write_upgrade(), to be
reused in NUMA hinting fault context soon.

Link: https://lkml.kernel.org/r/20221108174652.198904-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2022-11-08 18:46:49 +01:00 committed by Andrew Morton
parent c27f479ef5
commit eb309ec899
2 changed files with 18 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
include/linux/mm.h
View File

@ -2088,6 +2088,20 @@ extern unsigned long move_page_tables(struct vm_area_struct *vma,
#define MM_CP_UFFD_WP_ALL (MM_CP_UFFD_WP | \
MM_CP_UFFD_WP_RESOLVE)
int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot);
static inline bool vma_wants_manual_pte_write_upgrade(struct vm_area_struct *vma)
{
/*
* We want to check manually if we can change individual PTEs writable
* if we can't do that automatically for all PTEs in a mapping. For
* private mappings, that's always the case when we have write
* permissions as we properly have to handle COW.
*/
if (vma->vm_flags & VM_SHARED)
return vma_wants_writenotify(vma, vma->vm_page_prot);
return !!(vma->vm_flags & VM_WRITE);
}
extern unsigned long change_protection(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start,
unsigned long end, pgprot_t newprot,
@ -2227,8 +2241,6 @@ static inline int pte_devmap(pte_t pte)
}
#endif
int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot);
extern pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
spinlock_t **ptl);
static inline pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,

17
mm/mprotect.c
View File

@ -558,8 +558,8 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma,
struct mm_struct *mm = vma->vm_mm;
unsigned long oldflags = vma->vm_flags;
long nrpages = (end - start) >> PAGE_SHIFT;
unsigned int mm_cp_flags = 0;
unsigned long charged = 0;
bool try_change_writable;
pgoff_t pgoff;
int error;
@ -637,20 +637,11 @@ success:
* held in write mode.
*/
vma->vm_flags = newflags;
/*
* We want to check manually if we can change individual PTEs writable
* if we can't do that automatically for all PTEs in a mapping. For
* private mappings, that's always the case when we have write
* permissions as we properly have to handle COW.
*/
if (vma->vm_flags & VM_SHARED)
try_change_writable = vma_wants_writenotify(vma, vma->vm_page_prot);
else
try_change_writable = !!(vma->vm_flags & VM_WRITE);
if (vma_wants_manual_pte_write_upgrade(vma))
mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
vma_set_page_prot(vma);
change_protection(tlb, vma, start, end, vma->vm_page_prot,
try_change_writable ? MM_CP_TRY_CHANGE_WRITABLE : 0);
change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags);
/*
* Private VM_LOCKED VMA becoming writable: trigger COW to avoid major