On Thu, 7 Nov 2024 09:23:35 -0500 Johannes Weiner <hannes@xxxxxxxxxxx> > On Tue, Nov 05, 2024 at 05:23:23PM -0800, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 59b723cd2adb Linux 6.12-rc6 > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=1076c740580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=b77c8a55ccf1d9e2 > > dashboard link: https://syzkaller.appspot.com/bug?extid=078be8bfa863cb9e0c6b > > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167aa1f7980000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=110d86a7980000 #syz test The syzbot console output indicates a virtual environment where swapfile is on a rotational device. In this case, clusters aren't actually used, and si->full_clusters is not initialized. Daan's report is from qemu, so likely rotational too. Make sure to only schedule the cluster reclaim work when clusters are actually in use. Link: https://lore.kernel.org/lkml/672ac50b.050a0220.2edce.1517.GAE@xxxxxxxxxx/ Link: https://github.com/systemd/systemd/issues/35044 Fixes: 5168a68eb78f ("mm, swap: avoid over reclaim of full clusters") Reported-by: syzbot+078be8bfa863cb9e0c6b@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-by: Daan De Meyer <daan.j.demeyer@xxxxxxxxx> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> --- mm/swapfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 46bd4b1a3c07..9c85bd46ab7f 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -929,7 +929,7 @@ static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, si->highest_bit = 0; del_from_avail_list(si); - if (vm_swap_full()) + if (si->cluster_info && vm_swap_full()) schedule_work(&si->reclaim_work); } } -- 2.47.0
