guest_memfd needs a way to unmap a folio from all userspace processes. This is required as part of a folio's truncation process. The function unmap_mapping_folio() provides exactly this functionality.
Move its declaration from the internal mm/internal.h to the public include/linux/mm.h and export the symbol. unmap_mapping_folio() will be used by guest_memfd in a later patch to implement a custom truncation function. No functional change intended. Signed-off-by: Ackerley Tng <[email protected]> --- include/linux/mm.h | 2 ++ mm/internal.h | 2 -- mm/memory.c | 2 ++ 3 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 7f04f1eaab15a..97fa861364590 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2690,6 +2690,7 @@ extern vm_fault_t handle_mm_fault(struct vm_area_struct *vma, extern int fixup_user_fault(struct mm_struct *mm, unsigned long address, unsigned int fault_flags, bool *unlocked); +void unmap_mapping_folio(struct folio *folio); void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, pgoff_t nr, bool even_cows); void unmap_mapping_range(struct address_space *mapping, @@ -2710,6 +2711,7 @@ static inline int fixup_user_fault(struct mm_struct *mm, unsigned long address, BUG(); return -EFAULT; } +static inline void unmap_mapping_folio(struct folio *folio) { } static inline void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, pgoff_t nr, bool even_cows) { } static inline void unmap_mapping_range(struct address_space *mapping, diff --git a/mm/internal.h b/mm/internal.h index f35dbcf99a86b..98351be76238b 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -953,7 +953,6 @@ static inline bool free_area_empty(struct free_area *area, int migratetype) struct anon_vma *folio_anon_vma(const struct folio *folio); #ifdef CONFIG_MMU -void unmap_mapping_folio(struct folio *folio); extern long populate_vma_page_range(struct vm_area_struct *vma, unsigned long start, unsigned long end, int *locked); extern long faultin_page_range(struct mm_struct *mm, unsigned long start, @@ -1131,7 +1130,6 @@ static inline struct file *maybe_unlock_mmap_for_io(struct vm_fault *vmf, return fpin; } #else /* !CONFIG_MMU */ -static inline void unmap_mapping_folio(struct folio *folio) { } static inline void mlock_new_folio(struct folio *folio) { } static inline bool need_mlock_drain(int cpu) { return false; } static inline void mlock_drain_local(void) { } diff --git a/mm/memory.c b/mm/memory.c index da360a6eb8a48..983bb25517cb7 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -78,6 +78,7 @@ #include <linux/sched/sysctl.h> #include <linux/pgalloc.h> #include <linux/uaccess.h> +#include <linux/kvm_types.h> #include <trace/events/kmem.h> @@ -4244,6 +4245,7 @@ void unmap_mapping_folio(struct folio *folio) last_index, &details); i_mmap_unlock_read(mapping); } +EXPORT_SYMBOL_FOR_KVM(unmap_mapping_folio); /** * unmap_mapping_pages() - Unmap pages from processes. -- 2.53.0.345.g96ddfc5eaa-goog
