mm: frontswap: split out __frontswap_unuse_pages
An attempt at making frontswap_shrink shorter and more readable. This patch
splits out walking through the swap list to find an entry with enough
pages to unuse.
Also, assert that the internal __frontswap_unuse_pages is called under swap
lock, since that part of code was previously directly happen inside the lock.
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/mm/frontswap.c b/mm/frontswap.c
index 5faf840..faa43b7 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -230,6 +230,41 @@
return totalpages;
}
+static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused,
+ int *swapid)
+{
+ int ret = -EINVAL;
+ struct swap_info_struct *si = NULL;
+ int si_frontswap_pages;
+ unsigned long total_pages_to_unuse = total;
+ unsigned long pages = 0, pages_to_unuse = 0;
+ int type;
+
+ assert_spin_locked(&swap_lock);
+ for (type = swap_list.head; type >= 0; type = si->next) {
+ si = swap_info[type];
+ si_frontswap_pages = atomic_read(&si->frontswap_pages);
+ if (total_pages_to_unuse < si_frontswap_pages) {
+ pages = pages_to_unuse = total_pages_to_unuse;
+ } else {
+ pages = si_frontswap_pages;
+ pages_to_unuse = 0; /* unuse all */
+ }
+ /* ensure there is enough RAM to fetch pages from frontswap */
+ if (security_vm_enough_memory_mm(current->mm, pages)) {
+ ret = -ENOMEM;
+ continue;
+ }
+ vm_unacct_memory(pages);
+ *unused = pages_to_unuse;
+ *swapid = type;
+ ret = 0;
+ break;
+ }
+
+ return ret;
+}
+
/*
* Frontswap, like a true swap device, may unnecessarily retain pages
* under certain circumstances; "shrink" frontswap is essentially a
@@ -240,11 +275,9 @@
*/
void frontswap_shrink(unsigned long target_pages)
{
- struct swap_info_struct *si = NULL;
- int si_frontswap_pages;
unsigned long total_pages = 0, total_pages_to_unuse;
- unsigned long pages = 0, pages_to_unuse = 0;
- int type;
+ unsigned long pages_to_unuse = 0;
+ int type, ret;
bool locked = false;
/*
@@ -258,22 +291,8 @@
if (total_pages <= target_pages)
goto out;
total_pages_to_unuse = total_pages - target_pages;
- for (type = swap_list.head; type >= 0; type = si->next) {
- si = swap_info[type];
- si_frontswap_pages = atomic_read(&si->frontswap_pages);
- if (total_pages_to_unuse < si_frontswap_pages) {
- pages = pages_to_unuse = total_pages_to_unuse;
- } else {
- pages = si_frontswap_pages;
- pages_to_unuse = 0; /* unuse all */
- }
- /* ensure there is enough RAM to fetch pages from frontswap */
- if (security_vm_enough_memory_mm(current->mm, pages))
- continue;
- vm_unacct_memory(pages);
- break;
- }
- if (type < 0)
+ ret = __frontswap_unuse_pages(total_pages_to_unuse, &pages_to_unuse, &type);
+ if (ret < 0)
goto out;
locked = false;
spin_unlock(&swap_lock);