From: Longlong Xia <xialonglong1@xxxxxxxxxx> commit 7717fc1a12f88701573f9ed897cc4f6699c661e3 upstream. 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. Link: https://lkml.kernel.org/r/20230128094757.1060525-1-xialonglong1@xxxxxxxxxx Signed-off-by: Longlong Xia <xialonglong1@xxxxxxxxxx> Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Cc: Chen Wandun <chenwandun@xxxxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> Cc: Nanyong Sun <sunnanyong@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/swapfile.c | 1 + 1 file changed, 1 insertion(+) --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1008,6 +1008,7 @@ start_over: 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:
