@@ -106,6 +106,7 @@ static atomic_t proc_poll_event = ATOMIC_INIT(0);
atomic_t nr_rotate_swap = ATOMIC_INIT(0);
static unsigned int workingset_restore_limit;
+static unsigned int swapfile_write_enable;
static struct swap_info_struct *swap_type_to_swap_info(int type)
{
@@ -127,7 +128,7 @@ bool swap_folio_hot(struct folio *folio, bool hotness)
unsigned long restores;
int delta;
- if (hotness)
+ if (!swapfile_write_enable || hotness)
return true;
if (folio_test_swapbacked(folio) && folio_test_hot(folio)) {
@@ -2775,10 +2776,46 @@ const struct proc_ops workingset_restore_limit_fops = {
.proc_write = workingset_restore_limit_write,
};
+static ssize_t swapfile_write_enable_write(struct file *file,
+ const char __user *ubuf,
+ size_t count, loff_t *pos)
+{
+ unsigned int val;
+ int ret;
+
+ ret = kstrtouint_from_user(ubuf, count, 10, &val);
+ if (ret)
+ return ret;
+
+ swapfile_write_enable = val;
+
+ return count;
+}
+
+static int swapfile_write_enable_show(struct seq_file *m, void *v)
+{
+ seq_printf(m, "%d\n", swapfile_write_enable);
+ return 0;
+}
+
+static int swapfile_write_enable_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, swapfile_write_enable_show, inode->i_private);
+}
+
+const struct proc_ops swapfile_write_enable_fops = {
+ .proc_open = swapfile_write_enable_open,
+ .proc_read = seq_read,
+ .proc_lseek = seq_lseek,
+ .proc_release = seq_release,
+ .proc_write = swapfile_write_enable_write,
+};
+
static int __init procswaps_init(void)
{
proc_create("swaps", 0, NULL, &swaps_proc_ops);
proc_create("workingset_restore_limit", S_IALLUGO, NULL, &workingset_restore_limit_fops);
+ proc_create("swapfile_write_enable", S_IALLUGO, NULL, &swapfile_write_enable_fops);
return 0;
}
When the user does not want to write back cold pages to swapfile, set /proc/swapfile_write_enable to 0. At this time, all anon pages, regardless of hot or cold status, will be written back to the zram device. Signed-off-by: Lincheng Yang <lincheng.yang@transsion.com> --- mm/swapfile.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-)