[PATCH v2 6/6] mm: constify the pte_offset_map_ro_nolock() return value
Pedro Falcato <[email protected]>
| Newsgroups | gmane.linux.ports.ppc64.devel,gmane.linux.ports.arm.kernel,gmane.linux.kernel,gmane.linux.ports.parisc,gmane.linux.kernel.mm,gmane.linux.file-systems |
|---|---|
| Message-ID | <[email protected]> |
Constify the pte_t * retval from pte_offset_map_ro_nolock(), for which it is already pledged that accesses must be read-only. With it, convert the three treewide users to use const pte_t *. khugepaged passes the result right down to fault code (do_swap_page()). This leads to a complicated set of conditions that, in order to be correct, must not install anything into *vmf->pte. This is not trivial to work around in fault code, and as such just trivially cast to non-const pte_t* in the meantime. The other users are far more trivial and the conversion is equally trivially simple. Signed-off-by: Pedro Falcato <[email protected]> --- arch/powerpc/mm/pgtable.c | 2 +- include/linux/mm.h | 4 ++-- include/linux/pgtable.h | 2 +- mm/filemap.c | 2 +- mm/khugepaged.c | 2 +- mm/pgtable-generic.c | 4 ++-- 6 files changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index a9be337be3e4..e29db41b6043 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -390,7 +390,7 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr) p4d_t *p4d; pud_t *pud; pmd_t *pmd; - pte_t *pte; + const pte_t *pte; spinlock_t *ptl; if (mm == &init_mm) diff --git a/include/linux/mm.h b/include/linux/mm.h index 7fabe6c66b4b..acf5a5e31d34 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3885,8 +3885,8 @@ static inline pte_t *pte_offset_map(pmd_t *pmd, unsigned long addr) pte_t *pte_offset_map_lock(struct mm_struct *mm, pmd_t *pmd, unsigned long addr, spinlock_t **ptlp); -pte_t *pte_offset_map_ro_nolock(struct mm_struct *mm, pmd_t *pmd, - unsigned long addr, spinlock_t **ptlp); +const pte_t *pte_offset_map_ro_nolock(struct mm_struct *mm, pmd_t *pmd, + unsigned long addr, spinlock_t **ptlp); pte_t *pte_offset_map_rw_nolock(struct mm_struct *mm, pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp, spinlock_t **ptlp); diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index dc418553e57a..dd51e722c535 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -112,7 +112,7 @@ static inline pte_t *__pte_map(pmd_t *pmd, unsigned long address) { return pte_offset_kernel(pmd, address); } -static inline void pte_unmap(pte_t *pte) +static inline void pte_unmap(const pte_t *pte) { rcu_read_unlock(); } diff --git a/mm/filemap.c b/mm/filemap.c index 6afec636881f..af5d3fcd1b05 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3490,7 +3490,7 @@ static vm_fault_t filemap_fault_recheck_pte_none(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; vm_fault_t ret = 0; - pte_t *ptep; + const pte_t *ptep; /* * We might have COW'ed a pagecache folio and might now have an mlocked diff --git a/mm/khugepaged.c b/mm/khugepaged.c index b237f6e7662a..09efac93a8c6 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1170,7 +1170,7 @@ static enum scan_result __collapse_huge_page_swapin(struct mm_struct *mm, * Here the ptl is only used to check pte_same() in * do_swap_page(), so readonly version is enough. */ - pte = pte_offset_map_ro_nolock(mm, pmd, addr, &ptl); + pte = (pte_t *) pte_offset_map_ro_nolock(mm, pmd, addr, &ptl); if (!pte) { mmap_read_unlock(mm); result = SCAN_NO_PTE_TABLE; diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index b91b1a98029c..2cfc6e608ef4 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -308,8 +308,8 @@ pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp) return NULL; } -pte_t *pte_offset_map_ro_nolock(struct mm_struct *mm, pmd_t *pmd, - unsigned long addr, spinlock_t **ptlp) +const pte_t *pte_offset_map_ro_nolock(struct mm_struct *mm, pmd_t *pmd, + unsigned long addr, spinlock_t **ptlp) { pmd_t pmdval; pte_t *pte; -- 2.55.0