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From: Jeff Layton <jlayton@primarydata.com>
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Date: Wed, 14 Jan 2015 13:08:57 -0500
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Subject: [PATCH] nfs: don't call blocking operations while !TASK_RUNNING
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Bruce reported seeing this warning pop when mounting using v4.1:
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------------[ cut here ]------------
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WARNING: CPU: 1 PID: 1121 at kernel/sched/core.c:7300 __might_sleep+0xbd/0xd0()
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do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810ff58f>] prepare_to_wait+0x2f/0x90
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Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace sunrpc fscache ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_timer ppdev joydev snd virtio_console virtio_balloon pcspkr serio_raw parport_pc parport pvpanic floppy soundcore i2c_piix4 virtio_blk virtio_net qxl drm_kms_helper ttm drm virtio_pci virtio_ring ata_generic virtio pata_acpi
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CPU: 1 PID: 1121 Comm: nfsv4.1-svc Not tainted 3.19.0-rc4+ #25
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Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153950- 04/01/2014
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0000000000000000 000000004e5e3f73 ffff8800b998fb48 ffffffff8186ac78
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0000000000000000 ffff8800b998fba0 ffff8800b998fb88 ffffffff810ac9da
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ffff8800b998fb68 ffffffff81c923e7 00000000000004d9 0000000000000000
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Call Trace:
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[<ffffffff8186ac78>] dump_stack+0x4c/0x65
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[<ffffffff810ac9da>] warn_slowpath_common+0x8a/0xc0
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[<ffffffff810aca65>] warn_slowpath_fmt+0x55/0x70
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[<ffffffff810ff58f>] ? prepare_to_wait+0x2f/0x90
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[<ffffffff810ff58f>] ? prepare_to_wait+0x2f/0x90
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[<ffffffff810dd2ad>] __might_sleep+0xbd/0xd0
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[<ffffffff8124c973>] kmem_cache_alloc_trace+0x243/0x430
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[<ffffffff810d941e>] ? groups_alloc+0x3e/0x130
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[<ffffffff810d941e>] groups_alloc+0x3e/0x130
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[<ffffffffa0301b1e>] svcauth_unix_accept+0x16e/0x290 [sunrpc]
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[<ffffffffa0300571>] svc_authenticate+0xe1/0xf0 [sunrpc]
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[<ffffffffa02fc564>] svc_process_common+0x244/0x6a0 [sunrpc]
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[<ffffffffa02fd044>] bc_svc_process+0x1c4/0x260 [sunrpc]
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[<ffffffffa03d5478>] nfs41_callback_svc+0x128/0x1f0 [nfsv4]
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[<ffffffff810ff970>] ? wait_woken+0xc0/0xc0
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[<ffffffffa03d5350>] ? nfs4_callback_svc+0x60/0x60 [nfsv4]
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[<ffffffff810d45bf>] kthread+0x11f/0x140
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[<ffffffff810ea815>] ? local_clock+0x15/0x30
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[<ffffffff810d44a0>] ? kthread_create_on_node+0x250/0x250
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[<ffffffff81874bfc>] ret_from_fork+0x7c/0xb0
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[<ffffffff810d44a0>] ? kthread_create_on_node+0x250/0x250
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---[ end trace 675220a11e30f4f2 ]---
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nfs41_callback_svc does most of its work while in TASK_INTERRUPTIBLE,
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which is just wrong. Fix that by finishing the wait immediately if we've
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found that the list has something on it.
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Also, we don't expect this kthread to accept signals, so we should be
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using a TASK_UNINTERRUPTIBLE sleep instead. That however, opens us up
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hung task warnings from the watchdog, so have the schedule_timeout
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wake up every 60s if there's no callback activity.
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Reported-by: "J. Bruce Fields" <bfields@fieldses.org>
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Signed-off-by: Jeff Layton <jlayton@primarydata.com>
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Cc: stable@vger.kernel.org
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Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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---
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fs/nfs/callback.c | 8 +++++---
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1 file changed, 5 insertions(+), 3 deletions(-)
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diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
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index b8fb3a4ef649..351be9205bf8 100644
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--- a/fs/nfs/callback.c
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+++ b/fs/nfs/callback.c
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@@ -128,22 +128,24 @@ nfs41_callback_svc(void *vrqstp)
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if (try_to_freeze())
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continue;
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- prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
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+ prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_UNINTERRUPTIBLE);
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spin_lock_bh(&serv->sv_cb_lock);
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if (!list_empty(&serv->sv_cb_list)) {
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req = list_first_entry(&serv->sv_cb_list,
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struct rpc_rqst, rq_bc_list);
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list_del(&req->rq_bc_list);
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spin_unlock_bh(&serv->sv_cb_lock);
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+ finish_wait(&serv->sv_cb_waitq, &wq;;
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dprintk("Invoking bc_svc_process()\n");
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error = bc_svc_process(serv, req, rqstp);
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dprintk("bc_svc_process() returned w/ error code= %d\n",
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error);
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} else {
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spin_unlock_bh(&serv->sv_cb_lock);
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- schedule();
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+ /* schedule_timeout to game the hung task watchdog */
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+ schedule_timeout(60 * HZ);
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+ finish_wait(&serv->sv_cb_waitq, &wq;;
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}
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- finish_wait(&serv->sv_cb_waitq, &wq;;
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}
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return 0;
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}
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--
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2.1.0
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