On Tue, Oct 23, 2012 at 12:46:21PM -0400, J. Bruce Fields wrote: > On Tue, Oct 23, 2012 at 05:32:21PM +0100, Nix wrote: > > On 23 Oct 2012, J. Bruce Fields uttered the following: > > > nfs-utils shouldn't be capable of oopsing the kernel, so from my > > > (selfish) point of view I'd actually rather you stick with whatever you > > > have and try to reproduce the oops. > > > > Reproduced in 3.6.3, not in 3.6.1, not tried 3.6.2. Capturing it was > > rendered somewhat difficult by an ext4/JBD2 bug which leads to data loss > > in /var on every reboot out of 3.6.1 and on some reboots out of 3.6.3 (I > > have runs of NULs in my logs now, which keep eating the oopses): > > > > [while in 3.6.1] > > [ 88.565698] JBD2: Spotted dirty metadata buffer (dev = dm-5, blocknr = 0). There's a risk of filesystem corruption in case of system crash. > > [ 88.799263] JBD2: Spotted dirty metadata buffer (dev = dm-5, blocknr = 0). There's a risk of filesystem corruption in case of system crash. > > [ 89.648152] ------------[ cut here ]------------ > > [ 89.648386] WARNING: at fs/inode.c:280 drop_nlink+0x25/0x42() > > [ 89.648614] Hardware name: empty > > [ 89.648833] Modules linked in: firewire_ohci firewire_core [last unloaded: microcode] > > [ 89.649382] Pid: 1484, comm: dhcpd Not tainted 3.6.1-dirty #1 > > [ 89.649610] Call Trace: > > [ 89.649832] [<ffffffff810608c0>] warn_slowpath_common+0x83/0x9b > > [ 89.650063] [<ffffffff810608f2>] warn_slowpath_null+0x1a/0x1c > > [ 89.650292] [<ffffffff8112efbf>] drop_nlink+0x25/0x42 > > [ 89.650533] [<ffffffff81187112>] ext4_dec_count+0x26/0x28 > > [ 89.650763] [<ffffffff8118abb8>] ext4_rename+0x4ec/0x7b4 > > [ 89.650993] [<ffffffff81125d81>] ? vfs_rename+0xbe/0x3b7 > > [ 89.651224] [<ffffffff81125f3f>] vfs_rename+0x27c/0x3b7 > > [ 89.651454] [<ffffffff81127a53>] sys_renameat+0x1b1/0x228 > > [ 89.651682] [<ffffffff8114bda1>] ? fsnotify+0x226/0x249 > > [ 89.651911] [<ffffffff81239b75>] ? security_inode_permission+0x1e/0x20 > > [ 89.652145] [<ffffffff8111a240>] ? vfs_write+0x116/0x142 > > [ 89.652372] [<ffffffff81127ae5>] sys_rename+0x1b/0x1e > > [ 89.652601] [<ffffffff814fffa2>] system_call_fastpath+0x16/0x1b > > [...] > > [while having just booted into 3.6.1 after some time in 3.6.3: the FS > > was clean, and fscked on the previous boot into 3.6.3 after a previous > > instance of this bug] > > Oct 23 17:18:26 spindle crit: [ 67.625319] EXT4-fs error (device dm-5): mb_free_blocks:1300: group 65, block 2143748:freeing already freed block (bit 13828) > > > > This may well be a 3.6.1-specific bug fixed in 3.6.3, but it's hard to > > tell since most of my reboots are 3.6.1->3.6.3 or vice versa right now. > > > > > > Anyway, here's the NFSv4 oops (not a panic: it helps if I remember to > > turn off panic_on_oops when I come home from the holidays). > > > > It's a lockd problem, and probably happens during delivery of mail over > > NFS (my mailserver load soars when it happens): > > > > [ 813.110354] ------------[ cut here ]------------ > > [ 813.110585] kernel BUG at fs/lockd/mon.c:150! > > So nsm_mon_unmon() is being passed a NULL client. > > There are three container patches between 3.6.1 and 3.6.3: > > lockd: per-net NSM client creation and destruction helpers introduced > lockd: use rpc client's cl_nodename for id encoding > lockd: create and use per-net NSM RPC clients on MON/UNMON requests > > and that last does change nsm_monitor's call to nsm_mon_unmon, so that's > almost certainly it.... > > Looks like there's some confusion about whether nsm_client_get() returns > NULL or an error? The return from nsm_client_get() is either from nsm_create() or from ln->nsm_clnt. nsm_create's return is from rpc_create, and it doesn't look possible for rpc_creat to return NULL. So probably we have some case where, while holding ln->nsm_clnt_lock, you can see ln->nsm_users nonzero, but ln->nsm_clnt NULL ? --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
