On Mon, Nov 22, 2021 at 10:50:34AM +1100, NeilBrown wrote: > On Thu, 18 Nov 2021, J. Bruce Fields wrote: > > On Wed, Nov 17, 2021 at 11:46:49AM +1100, NeilBrown wrote: > > > I have a dream of making nfsd threads start and stop dynamically. > > > > It's a good dream! > > > > I haven't had a chance to look at these at all yet, I just kicked off > > tests to run overnight, and woke up to the below. > > > > This happened on the client, probably the first time it attempted to do > > an nfsv4 mount, so something went wrong with setup of the callback > > server. > > I cannot reproduce this and cannot see any way it could possible happen. Huh. Well, it's possible I mixed up the results somehow. I'll see if I can reproduce tonight or tomorrow. > Could you please confirm the patches were applied on a vanilla 5.1.6-rc1 > kernel, and that you don't have the "pool_mode" module parameter set. /sys/module/sunrpc/parameters/pool_mode is "global", the default. > As I said, serv->sv_nrpools is zero, so either it hasn't been set, or it > was set, but the 'serv' has been cleared and free (or freed and > reallocated and clearer), or that it was set to zero. > > svc_pool_map_get() doesn't explicitly protect against npools==0 (maybe > it should), only npools < 0. But even without that I cannot see it ever > setting ->npools to zero. > > I have changed refcounting, so maybe something could get freed early, > but all the changes I made happen *before* the point in the code where > it is crashing. OK, I'll take another look and let you know.... --b. > > So I'm thoroughly perplexed. > > Thanks, > NeilBrown > > > > > > --b. > > > > [ 285.585061] divide error: 0000 [#1] PREEMPT SMP KASAN PTI > > [ 285.585754] CPU: 0 PID: 5864 Comm: mount.nfs Not tainted 5.16.0-rc1-00014-g659e13af1f87 #1017 > > [ 285.586828] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-3.fc34 04/01/2014 > > [ 285.587828] RIP: 0010:svc_pool_for_cpu+0xc7/0x1b0 [sunrpc] > > [ 285.588501] Code: 8b ab f0 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 14 11 84 d2 74 09 80 fa 03 0f 8e 8d 00 00 00 31 d2 <f7> b3 e8 00 00 00 48 83 c4 08 5b 48 8d 04 52 48 c1 e0 06 48 01 e8 > > [ 285.590820] RSP: 0018:ffff88801526f8f8 EFLAGS: 00010246 > > [ 285.591418] RAX: 0000000000000000 RBX: ffff88800db3bc00 RCX: 1ffff11001b6779d > > [ 285.592267] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88800db3bce8 > > [ 285.593145] RBP: 0000000000000010 R08: 0000000000000001 R09: ffff888014b7403f > > [ 285.594057] R10: ffffed100296e807 R11: 0000000000000001 R12: ffff888014b74038 > > [ 285.594940] R13: ffff888014b74010 R14: ffff888014b74000 R15: ffff88800db3bc00 > > [ 285.595826] FS: 00007f489f68a440(0000) GS:ffff88806d400000(0000) knlGS:0000000000000000 > > [ 285.596851] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 285.597578] CR2: 00007f2dffa0b198 CR3: 000000000c486003 CR4: 0000000000170ef0 > > [ 285.598510] Call Trace: > > [ 285.598824] <TASK> > > [ 285.599097] svc_xprt_do_enqueue+0x164/0x900 [sunrpc] > > [ 285.599767] svc_xprt_received+0x181/0x3a0 [sunrpc] > > [ 285.600411] _svc_create_xprt+0x2bd/0x740 [sunrpc] > > [ 285.601049] ? svc_add_new_perm_xprt+0x140/0x140 [sunrpc] > > [ 285.601787] ? lock_release+0x3b8/0x6d0 > > [ 285.602318] ? nfs_callback_up+0x7ad/0xdb0 [nfsv4] > > [ 285.603617] svc_create_xprt+0x36/0x90 [sunrpc] > > [ 285.604306] nfs_callback_up+0x81f/0xdb0 [nfsv4] > > [ 285.604972] nfs4_init_client+0x1db/0x450 [nfsv4] > > [ 285.605605] ? nfs41_init_client+0x70/0x70 [nfsv4] > > [ 285.606304] nfs4_set_client+0x25f/0x410 [nfsv4] > > [ 285.606912] ? nfs4_add_trunk.isra.0+0x280/0x280 [nfsv4] > > [ 285.607606] nfs4_create_server+0x5f0/0xda0 [nfsv4] > > [ 285.608250] ? lock_is_held_type+0xd7/0x130 > > [ 285.608786] ? nfs4_server_common_setup+0x670/0x670 [nfsv4] > > [ 285.609505] ? __module_get+0x47/0x60 > > [ 285.610077] nfs4_try_get_tree+0xd3/0x250 [nfsv4] > > [ 285.610690] vfs_get_tree+0x8a/0x2d0 > > [ 285.611152] path_mount+0x3f9/0x19e0 > > [ 285.611608] ? debug_check_no_obj_freed+0x1f3/0x3c0 > > [ 285.612227] ? lock_is_held_type+0xd7/0x130 > > [ 285.612757] ? finish_automount+0x8c0/0x8c0 > > [ 285.613281] ? user_path_at_empty+0x45/0x50 > > [ 285.613832] ? rcu_read_lock_sched_held+0x3f/0x70 > > [ 285.614456] ? kmem_cache_free+0xd9/0x1b0 > > [ 285.614965] __x64_sys_mount+0x1d6/0x240 > > [ 285.615455] ? path_mount+0x19e0/0x19e0 > > [ 285.615941] ? syscall_enter_from_user_mode+0x1d/0x50 > > [ 285.616572] do_syscall_64+0x43/0x90 > > [ 285.617043] entry_SYSCALL_64_after_hwframe+0x44/0xae > > [ 285.617693] RIP: 0033:0x7f489fd4182e > > [ 285.618206] Code: 48 8b 0d 4d 16 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1a 16 0c 00 f7 d8 64 89 01 48 > > [ 285.620595] RSP: 002b:00007ffdc3bdd5b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 > > [ 285.621532] RAX: ffffffffffffffda RBX: 00007ffdc3bdd750 RCX: 00007f489fd4182e > > [ 285.622492] RDX: 000055da46c0a510 RSI: 000055da46c0a550 RDI: 000055da46c0c2f0 > > [ 285.623372] RBP: 00007ffdc3bdd750 R08: 000055da46c0d050 R09: 0037332e3232312e > > [ 285.624271] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > > [ 285.625158] R13: 00007ffdc3bdd660 R14: 000055da46c0ce00 R15: 000055da46c0ce90 > > [ 285.626097] </TASK> > > [ 285.626381] Modules linked in: nfsv4 rpcsec_gss_krb5 nfsv3 nfs_acl nfs lockd grace auth_rpcgss sunrpc > > [ 285.627622] ---[ end trace 0ea273cc87891325 ]--- > > [ 285.628222] RIP: 0010:svc_pool_for_cpu+0xc7/0x1b0 [sunrpc] > > [ 285.628945] Code: 8b ab f0 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 14 11 84 d2 74 09 80 fa 03 0f 8e 8d 00 00 00 31 d2 <f7> b3 e8 00 00 00 48 83 c4 08 5b 48 8d 04 52 48 c1 e0 06 48 01 e8 > > [ 285.631830] RSP: 0018:ffff88801526f8f8 EFLAGS: 00010246 > > [ 285.632557] RAX: 0000000000000000 RBX: ffff88800db3bc00 RCX: 1ffff11001b6779d > > [ 285.634319] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88800db3bce8 > > [ 285.635430] RBP: 0000000000000010 R08: 0000000000000001 R09: ffff888014b7403f > > [ 285.636408] R10: ffffed100296e807 R11: 0000000000000001 R12: ffff888014b74038 > > [ 285.637369] R13: ffff888014b74010 R14: ffff888014b74000 R15: ffff88800db3bc00 > > [ 285.638346] FS: 00007f489f68a440(0000) GS:ffff88806d400000(0000) knlGS:0000000000000000 > > [ 285.639434] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 285.640233] CR2: 00007f2dffa0b198 CR3: 000000000c486003 CR4: 0000000000170ef0 > > [ 285.641194] note: mount.nfs[5864] exited with preempt_count 1 > > [ 562.003788] kworker/dying (773) used greatest stack depth: 23128 bytes left > > [ 1356.888419] clocksource: timekeeping watchdog on CPU1: acpi_pm retried 2 times before success > > [ 2396.888656] clocksource: timekeeping watchdog on CPU1: acpi_pm retried 2 times before success > > [ 3071.387007] clocksource: timekeeping watchdog on CPU0: acpi_pm retried 2 times before success > > [ 3074.395010] clocksource: timekeeping watchdog on CPU0: acpi_pm retried 2 times before success > > [ 3082.395298] clocksource: timekeeping watchdog on CPU0: acpi_pm retried 2 times before success > > [ 5736.389488] clocksource: timekeeping watchdog on CPU0: acpi_pm retried 2 times before success > > [root@test3 ~]# uname -a > > Linux test3.fieldses.org 5.16.0-rc1-00014-g659e13af1f87 #1017 SMP PREEMPT Tue Nov 16 20:51:49 EST 2021 x86_64 x86_64 x86_64 GNU/Linux > > > >
