etmem: Add a scan flag to support specified page swap-out

euleros inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5DC4A
CVE: NA

-------------------------------------------------

etmem, the memory vertical expansion technology,

The existing memory expansion tool etmem swaps out all pages that can be
swapped out for the process by default, unless the page is marked with
lock flag.

The function of swapping out specified pages is added. The process adds
VM_SWAPFLAG flags for pages to be swapped out. The etmem adds filters to
the scanning module and swaps out only these pages.
Signed-off-by: Nliubo <liubo254@huawei.com>
Reviewed-by: NMiaohe Lin <linmiaohe@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/proc/etmem_scan.c

@@ -1187,6 +1187,11 @@ static int mm_idle_test_walk(unsigned long start, unsigned long end,
 				 struct mm_walk *walk)
 {
 	struct vm_area_struct *vma = walk->vma;
+	struct page_idle_ctrl *pic = walk->private;
+
+	/* If the specified page swapout is set, the untagged vma is skipped. */
+	if ((pic->flags & VMA_SCAN_FLAG) && !(vma->vm_flags & VM_SWAPFLAG))
+		return 1;
 
 	if (vma->vm_file) {
 		if (is_vm_hugetlb_page(vma))
@@ -1325,6 +1330,12 @@ static long page_scan_ioctl(struct file *filp, unsigned int cmd, unsigned long a
 	case IDLE_SCAN_REMOVE_FLAGS:
 		filp->f_flags &= ~flags;
 		break;
+	case VMA_SCAN_ADD_FLAGS:
+		filp->f_flags |= flags;
+		break;
+	case VMA_SCAN_REMOVE_FLAGS:
+		filp->f_flags &= ~flags;
+		break;
 	default:
 		return -EOPNOTSUPP;
 	}

fs/proc/etmem_scan.h

@@ -12,13 +12,16 @@
 #define SCAN_AS_HUGE		0100000000      /* treat normal page as hugepage in vm */
 #define SCAN_IGN_HOST		0200000000      /* ignore host access when scan vm */
 #define VM_SCAN_HOST		0400000000      /* scan and add host page for vm hole(internal) */
+#define VMA_SCAN_FLAG           0x1000        /* scan the specifics vma with flag */
 
 #define ALL_SCAN_FLAGS		(SCAN_HUGE_PAGE | SCAN_SKIM_IDLE | SCAN_DIRTY_PAGE | \
-		SCAN_AS_HUGE | SCAN_IGN_HOST | VM_SCAN_HOST)
+				SCAN_AS_HUGE | SCAN_IGN_HOST | VM_SCAN_HOST | VMA_SCAN_FLAG)
 
 #define IDLE_SCAN_MAGIC         0x66
 #define IDLE_SCAN_ADD_FLAGS	_IOW(IDLE_SCAN_MAGIC, 0x0, unsigned int)
 #define IDLE_SCAN_REMOVE_FLAGS	_IOW(IDLE_SCAN_MAGIC, 0x1, unsigned int)
+#define VMA_SCAN_ADD_FLAGS      _IOW(IDLE_SCAN_MAGIC, 0x2, unsigned int)
+#define VMA_SCAN_REMOVE_FLAGS   _IOW(IDLE_SCAN_MAGIC, 0x3, unsigned int)
 
 enum ProcIdlePageType {
 	PTE_ACCESSED,	/* 4k page */

fs/proc/etmem_swap.c

@@ -63,6 +63,7 @@ static ssize_t swap_pages_write(struct file *file, const char __user *buf,
 		ret = kstrtoul(p, 16, &vaddr);
 		if (ret != 0)
 			continue;
+
 		/* If get page struct failed, ignore it, get next page */
 		page = get_page_from_vaddr(mm, vaddr);
 		if (!page)

include/linux/mm.h

@@ -326,6 +326,10 @@ extern unsigned int kobjsize(const void *objp);
 
 #define VM_CHECKNODE	0x200000000
 
+#ifdef CONFIG_ETMEM
+#define VM_SWAPFLAG	0x400000000000000 /* memory swap out flag in vma */
+#endif
+
 #ifdef CONFIG_USERSWAP
 /* bit[32:36] is the protection key of intel, so use a large value for VM_USWAP */
 #define VM_USWAP      0x2000000000000000

include/uapi/asm-generic/mman-common.h

@@ -74,6 +74,9 @@
 #define MADV_COLD	20		/* deactivate these pages */
 #define MADV_PAGEOUT	21		/* reclaim these pages */
 
+#define MADV_SWAPFLAG   203		/* for memory to be swap out */
+#define MADV_SWAPFLAG_REMOVE 204
+
 /* compatibility flags */
 #define MAP_FILE	0
 

mm/madvise.c

@@ -126,6 +126,14 @@ static long madvise_behavior(struct vm_area_struct *vma,
 		if (error)
 			goto out_convert_errno;
 		break;
+#ifdef CONFIG_ETMEM
+	case MADV_SWAPFLAG:
+		new_flags |= VM_SWAPFLAG;
+		break;
+	case MADV_SWAPFLAG_REMOVE:
+		new_flags &= ~VM_SWAPFLAG;
+		break;
+#endif
 	}
 
 	if (new_flags == vma->vm_flags) {
@@ -969,9 +977,12 @@ madvise_behavior_valid(int behavior)
 #ifdef CONFIG_MEMORY_FAILURE
 	case MADV_SOFT_OFFLINE:
 	case MADV_HWPOISON:
+#endif
+#ifdef CONFIG_ETMEM
+	case MADV_SWAPFLAG:
+	case MADV_SWAPFLAG_REMOVE:
 #endif
 		return true;
-
 	default:
 		return false;
 	}
@@ -1041,6 +1052,10 @@ process_madvise_behavior_valid(int behavior)
  *		easily if memory pressure hanppens.
  *  MADV_PAGEOUT - the application is not expected to use this memory soon,
  *		page out the pages in this range immediately.
+ *  MADV_SWAPFLAG - Used in the etmem memory extension feature, the process
+ *		specifies the memory swap area by adding a flag to a specific
+ *		vma address.
+ *  MADV_SWAPFLAG_REMOVE - remove the specific vma flag
  *
  * return values:
  *  zero    - success