From: Jeff Layton <jlayton@xxxxxxxxxx> Vasily reported: If we start nfsd from another net namespace lockd_up_net() calls set_grace_period() that adds lockd_manager into per-netns list. Then we stop nfsd server. If lockd have another users it will not be destroyed and lock_manager will not be removed from list. If lockd had no other users then lockd kernel thread will be stopped, but "remove" lock_manager strongly from init_net. When nfsd in net namespace will started again we get "list_add double add" error. Reproducer: - do not start nfsd on host - create new net namespace # unshare -n -m ; mount -t nfsd nfsd /proc/fs/nfsd - start nfsd from newly created net namespace # echo 1 > /proc/fs/nfsd/threads - stop and restart it again # echo 0 > /proc/fs/nfsd/thread # echo 1 > /proc/fs/nfsd/thread Result: "list_add double add" in set_grace_period() [ 414.644407] NFSD: attempt to initialize umh client tracking in a container ignored. [ 414.644533] NFSD: attempt to initialize legacy client tracking in a container ignored. [ 414.644562] NFSD: Unable to initialize client recovery tracking! (-22) [ 414.644585] NFSD: starting 90-second grace period (net ffff8df8f0243140) <<< 1st start [ 423.788079] nfsd: last server has exited, flushing export cache <<< stop [ 426.735772] list_add double add: new=ffff8df8f1db1310, prev=ffff8df93cac9348, next=ffff8df8f1db1310. [ 426.735833] ------------[ cut here ]------------ <<< 2nd start [ 426.735855] kernel BUG at lib/list_debug.c:31! [ 426.735876] invalid opcode: 0000 [#1] SMP [ 426.736011] CPU: 5 PID: 1423 Comm: bash Not tainted 4.14.0-rc6+ #2 [ 426.736011] Hardware name: Virtuozzo KVM, BIOS 1.9.1-5.3.2.vz7.7 04/01/2014 [ 426.736011] task: ffff8df8f2278040 task.stack: ffffa70b40ce4000 [ 426.736011] RIP: 0010:__list_add_valid+0x66/0x70 [ 426.736011] RSP: 0018:ffffa70b40ce7ce8 EFLAGS: 00010282 [ 426.736011] RAX: 0000000000000058 RBX: ffff8df8f1db1310 RCX: 0000000000000000 [ 426.736011] RDX: 0000000000000000 RSI: ffff8df93fd4e138 RDI: ffff8df93fd4e138 [ 426.736011] RBP: ffffa70b40ce7ce8 R08: 00000000000002ba R09: 0000000000000000 [ 426.736011] R10: 0000000000000010 R11: 00000000ffffffff R12: ffff8df93cac9348 [ 426.736011] R13: ffff8df8f1db1310 R14: ffff8df8f0243140 R15: 0000000000000000 [ 426.736011] FS: 00007f8c9389db40(0000) GS:ffff8df93fd40000(0000) knlGS:0000000000000000 [ 426.736011] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 426.736011] CR2: 00007f8c936848d0 CR3: 000000007ca88003 CR4: 00000000001606e0 [ 426.736011] Call Trace: [ 426.736011] locks_start_grace+0x40/0x70 [grace] [ 426.736011] set_grace_period+0x44/0x90 [lockd] [ 426.736011] lockd_up+0x2b2/0x350 [lockd] [ 426.736011] nfsd_svc+0x256/0x2b0 [nfsd] [ 426.736011] ? write_pool_threads+0x2b0/0x2b0 [nfsd] [ 426.736011] write_threads+0x80/0xe0 [nfsd] [ 426.736011] ? simple_transaction_get+0xb5/0xd0 [ 426.736011] nfsctl_transaction_write+0x48/0x80 [nfsd] [ 426.736011] __vfs_write+0x37/0x170 [ 426.736011] ? selinux_file_permission+0x105/0x120 [ 426.736011] ? security_file_permission+0x3b/0xc0 [ 426.736011] vfs_write+0xb1/0x1a0 [ 426.736011] SyS_write+0x55/0xc0 Make it safe to call locks_start_grace multiple times on the same lock_manager. If it's already on the global grace_list, then don't try to add it again. With this change, we also need to ensure that the nfsd4 lock manager initializes the list before we call locks_start_grace. While we're at it, move the rest of the nfsd_net initialization into nfs4_state_create_net. I see no reason to have it spread over two functions like it is today. Reported-by: Vasily Averin <vvs@xxxxxxxxxxxxx> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- Vasily, would this patch fix the panic you're seeing? We may still need to do something saner here, but this seems like it should at least prevent a double list_add. fs/nfs_common/grace.c | 3 ++- fs/nfsd/nfs4state.c | 7 ++++--- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/nfs_common/grace.c b/fs/nfs_common/grace.c index 420d3a0ab258..874ff25e12ac 100644 --- a/fs/nfs_common/grace.c +++ b/fs/nfs_common/grace.c @@ -30,7 +30,8 @@ locks_start_grace(struct net *net, struct lock_manager *lm) struct list_head *grace_list = net_generic(net, grace_net_id); spin_lock(&grace_lock); - list_add(&lm->list, grace_list); + if (list_empty(&lm->list)) + list_add(&lm->list, grace_list); spin_unlock(&grace_lock); } EXPORT_SYMBOL_GPL(locks_start_grace); diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 0c04f81aa63b..4aa78bd6f0bb 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -6944,6 +6944,10 @@ static int nfs4_state_create_net(struct net *net) INIT_LIST_HEAD(&nn->sessionid_hashtbl[i]); nn->conf_name_tree = RB_ROOT; nn->unconf_name_tree = RB_ROOT; + nn->boot_time = get_seconds(); + nn->grace_ended = false; + nn->nfsd4_manager.block_opens = true; + INIT_LIST_HEAD(&nn->nfsd4_manager.list); INIT_LIST_HEAD(&nn->client_lru); INIT_LIST_HEAD(&nn->close_lru); INIT_LIST_HEAD(&nn->del_recall_lru); @@ -7001,9 +7005,6 @@ nfs4_state_start_net(struct net *net) ret = nfs4_state_create_net(net); if (ret) return ret; - nn->boot_time = get_seconds(); - nn->grace_ended = false; - nn->nfsd4_manager.block_opens = true; locks_start_grace(net, &nn->nfsd4_manager); nfsd4_client_tracking_init(net); printk(KERN_INFO "NFSD: starting %ld-second grace period (net %p)\n", -- 2.13.6 -- 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
