From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Olivier B." <xen.list@daevel.fr>
Subject: Linux 3.2.2 & btrfs, on a DomU
Date: Fri, 27 Jan 2012 19:59:15 +0100
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Hi,

I switch one of my DomU to a 3.2.2 linux kernel (renamed in 2.6.42.2, for compatibility with some software), and I have some problem with btrfs.

I don't know if it's a btrfs or xen problem, the call trace is :

[56580.320024] INFO: rcu_sched detected stall on CPU 0 (t=15000 jiffies)
[56580.320024] Pid: 11505, comm: btrfs-delayed-m Tainted: G         C   2.6.42.2-dae-xen #2
[56580.320024] Call Trace:
[56580.320024]  <IRQ>  [<ffffffff81084719>] ? __rcu_pending+0x82/0x337
[56580.320024]  [<ffffffff810678bd>] ? tick_nohz_handler+0xbe/0xbe
[56580.320024]  [<ffffffff81084ccc>] ? rcu_check_callbacks+0x7e/0xae
[56580.320024]  [<ffffffff81050d44>] ? update_process_times+0x31/0x63
[56580.320024]  [<ffffffff8106791f>] ? tick_sched_timer+0x62/0x7e
[56580.320024]  [<ffffffff8105e8b4>] ? __run_hrtimer.isra.28+0x52/0xaa
[56580.320024]  [<ffffffff8105ee8c>] ? hrtimer_interrupt+0xd5/0x1a1
[56580.320024]  [<ffffffff8100537e>] ? xen_timer_interrupt+0x28/0x159
[56580.320024]  [<ffffffff81080097>] ? handle_irq_event_percpu+0x24/0x11c
[56580.320024]  [<ffffffff810824b1>] ? handle_percpu_irq+0x35/0x4c
[56580.320024]  [<ffffffff811cbe90>] ? __xen_evtchn_do_upcall+0x154/0x1eb
[56580.320024]  [<ffffffff8100525c>] ? xen_force_evtchn_callback+0x9/0xa
[56580.320024]  [<ffffffff811cd490>] ? xen_evtchn_do_upcall+0x22/0x32
[56580.320024]  [<ffffffff812f863e>] ? xen_do_hypervisor_callback+0x1e/0x30
[56580.320024]  <EOI>  [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000
[56580.320024]  [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000
[56580.320024]  [<ffffffff811cc7d5>] ? xen_poll_irq_timeout+0x38/0x44
[56580.320024]  [<ffffffff812ee21f>] ? xen_spin_lock_slow+0x86/0xdf
[56580.320024]  [<ffffffff8100688a>] ? __xen_spin_lock+0x32/0x3b
[56580.320024]  [<ffffffff8106bd6a>] ? do_raw_spin_lock+0x5/0x8
[56580.320024]  [<ffffffffa002badd>] ? find_free_extent.constprop.77+0x495/0x94b [btrfs]
[56580.320024]  [<ffffffffa00689fe>] ? btrfs_add_delayed_tree_ref+0x77/0x120 [btrfs]
[56580.320024]  [<ffffffffa002e61b>] ? btrfs_reserve_extent+0xa4/0x148 [btrfs]
[56580.320024]  [<ffffffffa002eadb>] ? btrfs_alloc_free_block+0x15d/0x283 [btrfs]
[56580.320024]  [<ffffffff81005842>] ? check_events+0x12/0x20
[56580.320024]  [<ffffffffa0021f3a>] ? __btrfs_cow_block+0x102/0x32c [btrfs]
[56580.320024]  [<ffffffffa0022257>] ? btrfs_cow_block+0xf3/0x102 [btrfs]
[56580.320024]  [<ffffffffa0024c84>] ? btrfs_search_slot+0x225/0x64e [btrfs]
[56580.320024]  [<ffffffffa00285f2>] ? lookup_inline_extent_backref+0xa8/0x360 [btrfs]
[56580.320024]  [<ffffffffa002a35c>] ? __btrfs_free_extent+0xcb/0x5c8 [btrfs]
[56580.320024]  [<ffffffff812f1dac>] ? __slab_free+0xd6/0x206
[56580.320024]  [<ffffffff810b9c65>] ? arch_local_irq_restore+0x7/0x8
[56580.320024]  [<ffffffffa002d87e>] ? run_clustered_refs+0x65f/0x6a9 [btrfs]
[56580.320024]  [<ffffffff81177fe4>] ? rb_next+0x39/0x3f
[56580.320024]  [<ffffffffa002d991>] ? btrfs_run_delayed_refs+0xc9/0x185 [btrfs]
[56580.320024]  [<ffffffff812ee18a>] ? xen_spin_unlock_slow+0x4d/0x5c
[56580.320024]  [<ffffffffa003b13a>] ? __btrfs_end_transaction+0x90/0x1dd [btrfs]
[56580.320024]  [<ffffffffa006ff08>] ? btrfs_async_run_delayed_node_done+0xf8/0x156 [btrfs]
[56580.320024]  [<ffffffffa005a150>] ? worker_loop+0x16a/0x45a [btrfs]
[56580.320024]  [<ffffffffa0059fe6>] ? btrfs_queue_worker+0x279/0x279 [btrfs]
[56580.320024]  [<ffffffff8105bbba>] ? kthread+0x76/0x7e
[56580.320024]  [<ffffffff812f84f4>] ? kernel_thread_helper+0x4/0x10
[56580.320024]  [<ffffffff812f65b3>] ? int_ret_from_sys_call+0x7/0x1b
[56580.320024]  [<ffffffff812f5cbc>] ? retint_restore_args+0x5/0x6
[56580.320024]  [<ffffffff812f84f0>] ? gs_change+0x13/0x13

I had the problem with 3.2, 3.2.1, then 3.2.2. With and without the renaming to 2.6.42.x.

The Xen version is 4.0.1 (from Debian amd64), and the Dom0 kernel is a 3.1.0 (also from Debian).

Thanks for any advice,

Olivier B.