The softlockup still occurs in get_swap_pages() under memory pressure.
64 CPU cores, 64GB memory, and 28 zram devices, the disksize of each
zram device is 50MB with same priority as si. Use the stress-ng tool
to increase memory pressure, causing the system to oom frequently.
The plist_for_each_entry_safe() loops in get_swap_pages() could reach
tens of thousands of times to find available space (extreme case:
cond_resched() is not called in scan_swap_map_slots()). Let's add
cond_resched() into get_swap_pages() when failed to find available
space to avoid softlockup.
Signed-off-by: Longlong Xia <xialonglong1@xxxxxxxxxx>
---
mm/swapfile.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 908a529bca12..4fa440e87cd6 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1100,6 +1100,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size)
goto check_out;
pr_debug("scan_swap_map of si %d failed to find offset\n",
si->type);
+ cond_resched();
spin_lock(&swap_avail_lock);
nextsi:
--
2.25.1
