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mm: split can_change_pte_writable() into private and shared parts

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In preparation for patch 6 and modularizing the code in general, split
can_change_pte_writable() into private and shared VMA parts.  No
functional change intended.

Link: https://lkml.kernel.org/r/20250718090244.21092-6-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dev Jain
2025-07-18 14:32:42 +05:30
committed by Andrew Morton
parent 57fae936b4
commit 45199f715b
1 changed files with 36 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

50
mm/mprotect.c
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@@ -40,11 +40,8 @@
#include "internal.h"
bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
pte_t pte)
static bool maybe_change_pte_writable(struct vm_area_struct *vma, pte_t pte)
{
struct page *page;
if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
return false;
@@ -60,16 +57,32 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
if (userfaultfd_pte_wp(vma, pte))
return false;
if (!(vma->vm_flags & VM_SHARED)) {
/*
* Writable MAP_PRIVATE mapping: We can only special-case on
* exclusive anonymous pages, because we know that our
* write-fault handler similarly would map them writable without
* any additional checks while holding the PT lock.
*/
page = vm_normal_page(vma, addr, pte);
return page && PageAnon(page) && PageAnonExclusive(page);
}
return true;
}
static bool can_change_private_pte_writable(struct vm_area_struct *vma,
unsigned long addr, pte_t pte)
{
struct page *page;
if (!maybe_change_pte_writable(vma, pte))
return false;
/*
* Writable MAP_PRIVATE mapping: We can only special-case on
* exclusive anonymous pages, because we know that our
* write-fault handler similarly would map them writable without
* any additional checks while holding the PT lock.
*/
page = vm_normal_page(vma, addr, pte);
return page && PageAnon(page) && PageAnonExclusive(page);
}
static bool can_change_shared_pte_writable(struct vm_area_struct *vma,
pte_t pte)
{
if (!maybe_change_pte_writable(vma, pte))
return false;
VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte));
@@ -83,6 +96,15 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
return pte_dirty(pte);
}
bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
pte_t pte)
{
if (!(vma->vm_flags & VM_SHARED))
return can_change_private_pte_writable(vma, addr, pte);
return can_change_shared_pte_writable(vma, pte);
}
static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep,
pte_t pte, int max_nr_ptes)
{