From: Shivam Kalra Extract page freeing and NR_VMALLOC stat accounting from vfree() into a reusable vm_area_free_pages() helper. The helper operates on a range [start_idx, end_idx) of pages from a vm_struct, making it suitable for both full free (vfree) and partial free (upcoming vrealloc shrink). Freed page pointers in vm->pages[] are set to NULL to prevent stale references when the vm_struct outlives the free (as in vrealloc shrink). Signed-off-by: Shivam Kalra --- mm/vmalloc.c | 34 +++++++++++++++++++++++++++------- 1 file changed, 27 insertions(+), 7 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 878c5b7bf837..1073abb6094e 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3416,6 +3416,32 @@ void vfree_atomic(const void *addr) schedule_work(&p->wq); } +/* + * vm_area_free_pages - free a range of pages from a vmalloc allocation + * @vm: the vm_struct containing the pages + * @start_idx: first page index to free (inclusive) + * @end_idx: last page index to free (exclusive) + * + * Free pages [start_idx, end_idx) updating NR_VMALLOC stat accounting. + * Freed vm->pages[] entries are set to NULL. + * Caller is responsible for unmapping (vunmap_range) and KASAN + * poisoning before calling this. + */ +static void vm_area_free_pages(struct vm_struct *vm, unsigned int start_idx, + unsigned int end_idx) +{ + unsigned int i; + + if (!(vm->flags & VM_MAP_PUT_PAGES)) { + for (i = start_idx; i < end_idx; i++) + mod_lruvec_page_state(vm->pages[i], NR_VMALLOC, -1); + } + free_pages_bulk(vm->pages + start_idx, end_idx - start_idx); + + for (i = start_idx; i < end_idx; i++) + vm->pages[i] = NULL; +} + /** * vfree - Release memory allocated by vmalloc() * @addr: Memory base address @@ -3436,7 +3462,6 @@ void vfree_atomic(const void *addr) void vfree(const void *addr) { struct vm_struct *vm; - int i; if (unlikely(in_interrupt())) { vfree_atomic(addr); @@ -3460,12 +3485,7 @@ void vfree(const void *addr) if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS)) vm_reset_perms(vm); - if (!(vm->flags & VM_MAP_PUT_PAGES)) { - for (i = 0; i < vm->nr_pages; i++) - mod_lruvec_page_state(vm->pages[i], NR_VMALLOC, -1); - } - free_pages_bulk(vm->pages, vm->nr_pages); - + vm_area_free_pages(vm, 0, vm->nr_pages); kvfree(vm->pages); kfree(vm); } -- 2.43.0