Commit eb309ec8 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

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: default avatarDavid 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c27f479e

include/linux/mm.h

+14 −2
Original line number Diff line number Diff line
@@ -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,

mm/mprotect.c

+4 −13
Original line number Diff line number Diff line
@@ -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 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, 
	 * 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