On 12.09.19 г. 9:11 ч., Nikolay Borisov wrote: > > > On 12.09.19 г. 7:38 ч., David Newall wrote: >> On 11/9/19 8:22 pm, Nikolay Borisov wrote: >>>> I saved it tohttps://davidnewall.com/kern.1 >>> Nothing useful in that log, everything seems normal. >> >> Thank you, again, for your help. I am grateful. >> >> If I understand the output, both df and mount are waiting for >> show_mountinfo which is waiting for btrfs_show_devname which is waiting >> to get a lock. They have to wait to find the devname for ten minutes. >> Is that really normal? > > It's normal for them to wait for the lock, it's not normal for the lock > to be taken for 10 minutes. > >> >> I'm not saying that btrfs is behind it, but it does seem like something >> is not right. > > From my POV what's wrong is the fact that btrfs transaction commit is > taking a long time. Is it possible that the underlying storage is > exhibiting problems e.g. a dying disk/ssd? Actually when the issue occurs again can you sample the output of echo w > /proc/sysrq-trigger. Because right now you have provided 3 samples in the course of I don't know how many minutes. So they just give a momentarily glimpse into what's happening. E.g. just because we saw btrfs transaction/btrfs_show_devname doesn't necessarily mean that's what's happening (Though having the same consistent state in the 3 logs kind of suggests otherwise). > >> >> I notice that there's a waiting btrfs-transation, too. I don't know >> what the transaction would be, and no doubt it's completely appropriate, >> even though the use of btrfs at that point is merely one mount (and one >> mount of ext2 over a sub-directory, probably no involvement by btrfs.) >> >> I see, too, that systemd is waiting for btrfs_show_devname. It's a >> pattern. >> >> I take your point about the kernel being somewhat old and accept that >> I'm unlikely to get far without confirming the problem on a recent kernel. >> >> >
