On Thu, Aug 03, 2023 at 02:06:46PM +0800, Aaron Lu wrote: > On Wed, Aug 02, 2023 at 07:54:38PM +0700, Bagas Sanjaya wrote: > > Hi, > > > > I notice a bug report on Bugzilla [1]. Quoting from it: > > > > > How to reproduce: > > > > > > Had 24 CPU Alderlake 16GB debian12 system running with default kernel (from makecondig) on 6.5-rc4, exercised with no swap to start with. > > > > > > using stress-ng tip commit 0f2ef02e9bc5abb3419c44be056d5fa3c97e0137 > > > (see https://github.com/ColinIanKing/stress-ng ) > > > > > > build and run stress-ng for say 60 minutes: > > > > > > ./stress-ng --cpu-online 50 --brk 50 --swap 50 --vmstat 1 -t 60m > > > > > > Will hang in mm/swapfile.c:718 add_to_avail_list+0x93/0xa0 > > > > > > See attached file for an image of the console on the hang (I'm trying to get the full stack dump). > > > > See Bugzilla for the full thread and attached console image. > > > > FWIW, I have to forward this bug report to the mailing lists because > > Thorsten noted that many developers don't take a look on Bugzilla > > (see the BZ thread). > > Thanks. > > I can reproduce this issue using below cmdline: > $ sudo ./stress-ng --brk 50 --swap 5 --vmstat 1 -t 60m > > I'll investigate what is happening. Hi Colin, Can you try the below diff on top of v6.5-rc4? It works for me here although I got the warn in a different place in get_swap_pages(): WARN(!si->highest_bit, "swap_info %d in list but !highest_bit\n", si->type); I think the warn you got in add_to_avail_list() due to the swap device is already in the list is similar, see below explanation. diff --git a/mm/swapfile.c b/mm/swapfile.c index 8e6dde68b389..cb7e93ec1933 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2330,7 +2330,8 @@ static void _enable_swap_info(struct swap_info_struct *p) * swap_info_struct. */ plist_add(&p->list, &swap_active_head); - add_to_avail_list(p); + if (p->highest_bit) + add_to_avail_list(p); } static void enable_swap_info(struct swap_info_struct *p, int prio, The finding is, if a swap device failed to be swapoff, then it will be reinsert_swap_info() -> _enable_swap_info() -> add_to_avail_list(). The problem is, this swap device may run out of space with its highest_bit being 0 and shouldn't be added to avail list. In your case, once its highest_bit becomes non-zero, it will go through add_to_avail_list() and since it's already in the list, thus the warn. If it works for you, I'll prepare a patch. Thanks.
