Date:	Tue, 07 Nov 2006 16:51:55 -0500
From:	Jeff Garzik <jeff@...zik.org>
To:	Paolo 'Blaisorblade' Giarrusso <blaisorblade@...oo.it>,
	Jeff Dike <jdike@...toit.com>
CC:	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: slow UML on x86-64, soft lockups

Recent 2.6.18 / 2.6.19-rc kernels run at the expected speed, on 32-bit 
x86, with a Fedora Core 5 or 6 UML userland.  However, on 64-bit x86-64 
with a 64-bit UML userland, the kernel is achingly slow.  It works, 
but...  Login takes several minutes (via ssh from host or xterm 
console), and soft lockup traces continually print to the screen (see 
output below).  Once logged into, programs work, but again, very slowly. 
  Commands which complete in under a second normally often takes minutes.

Any ideas?  I guess there is a bug in the 64-bit UML timer code?

	Jeff




BUG: soft lockup detected on CPU#0!
Call Trace:
61347c18:  [<6004a5be>] update_process_times+0x45/0x6d
61347c48:  [<60017d89>] timer_handler+0x31/0x58
61347c78:  [<600399f2>] sig_handler_common_skas+0xe6/0xfc
61347cb8:  [<60036d8e>] alarm_handler+0x4d/0x59
61347dc8:  [<6013da36>] __up_read+0x15/0x81
61347dd8:  [<6003705d>] set_signals+0x1a/0x2d
61347de8:  [<600188b6>] handle_page_fault+0x212/0x243
61347e48:  [<600189ef>] segv+0xa7/0x2ac
61347e88:  [<600196e2>] switch_to_skas+0x46/0x68
61347f28:  [<60018943>] segv_handler+0x5c/0x61
61347f48:  [<600384b4>] move_registers+0x33/0x4a
61347f68:  [<6003850e>] restore_registers+0x16/0x2e
61347f78:  [<6003925f>] userspace+0x5c/0x178
61347fd8:  [<60019808>] fork_handler+0x74/0x79

BUG: soft lockup detected on CPU#0!
Call Trace:
61347a98:  [<6004a5be>] update_process_times+0x45/0x6d
61347ac8:  [<60017d89>] timer_handler+0x31/0x58
61347af8:  [<600399f2>] sig_handler_common_skas+0xe6/0xfc
61347b28:  [<60019ad4>] do_ops+0x0/0x112
61347b38:  [<60036d8e>] alarm_handler+0x4d/0x59
61347bb8:  [<60019ad4>] do_ops+0x0/0x112
61347c08:  [<60018270>] fix_range_common+0x172/0x318
61347cc0:  [<60015c53>] find_phys_mapping+0x5/0x9
61347cf8:  [<600679ad>] free_hot_cold_page+0xe6/0x108
61347d18:  [<6003705d>] set_signals+0x1a/0x2d
61347d28:  [<6006dfd5>] zap_pte_range+0x197/0x225
61347d98:  [<60018333>] fix_range_common+0x235/0x318
61347da8:  [<60019ad4>] do_ops+0x0/0x112
61347e18:  [<6006d845>] free_pgtables+0x87/0x98
61347e58:  [<60072aa9>] unmap_region+0xe1/0xf0
61347ea8:  [<60072d29>] do_munmap+0xfc/0x11d
61347eb8:  [<60091e99>] mntput_no_expire+0x17/0x64
61347ee8:  [<60072d8f>] sys_munmap+0x45/0x61
61347ef8:  [<6007ecf0>] sys_close+0x7c/0xb1
61347f28:  [<60019abb>] handle_syscall+0x63/0x7c
61347f48:  [<60038ec4>] handle_trap+0xcb/0xd2
61347f78:  [<60039334>] userspace+0x131/0x178
61347fd8:  [<60019808>] fork_handler+0x74/0x79

BUG: soft lockup detected on CPU#0!
Call Trace:
60263bb8:  [<6004a5be>] update_process_times+0x45/0x6d
60263be8:  [<60017d89>] timer_handler+0x31/0x58
60263c18:  [<600399f2>] sig_handler_common_skas+0xe6/0xfc
60263c58:  [<60036d30>] real_alarm_handler+0x1e/0x2f
60263c68:  [<60036d8e>] alarm_handler+0x4d/0x59
60263cb8:  [<600169b5>] copy_to_user_proc+0x0/0x5
60263d98:  [<6003775a>] switch_timers+0x92/0xb2
60263e18:  [<600196fd>] switch_to_skas+0x61/0x68
60263e48:  [<60016588>] _switch_to+0x47/0x8d
60263e78:  [<601f35a2>] schedule+0x428/0x488
60263ec8:  [<600377bf>] idle_sleep+0x1e/0x23
60263ee8:  [<6001676d>] default_idle+0x2a/0x2c
60263ef8:  [<60036227>] os_getpid+0x10/0x12
60263f08:  [<60019934>] init_idle_skas+0x2c/0x30
60263f28:  [<6000153b>] start_kernel+0x1c7/0x1cc
60263f38:  [<60036227>] os_getpid+0x10/0x12
60263f48:  [<6001996b>] start_kernel_proc+0x33/0x3a
60263f68:  [<6003663b>] run_kernel_thread+0x42/0x4b
60263f78:  [<60019938>] start_kernel_proc+0x0/0x3a
60263fb8:  [<60036620>] run_kernel_thread+0x27/0x4b
60263fd8:  [<6001976b>] new_thread_handler+0x67/0x8f

BUG: soft lockup detected on CPU#0!
Call Trace:
61347788:  [<6004a5be>] update_process_times+0x45/0x6d
613477b8:  [<60017d89>] timer_handler+0x31/0x58
613477e8:  [<600399f2>] sig_handler_common_skas+0xe6/0xfc
61347828:  [<60036d8e>] alarm_handler+0x4d/0x59
61347890:  [<601620b3>] dev_queue_xmit+0x0/0x1cf
613478f8:  [<601620b5>] dev_queue_xmit+0x2/0x1cf
61347938:  [<601f35a2>] schedule+0x428/0x488
613479a8:  [<60053e20>] remove_wait_queue+0x15/0x45
613479b8:  [<6003705d>] set_signals+0x1a/0x2d
613479c8:  [<6008a46b>] free_poll_entry+0x11/0x1a
613479d8:  [<6008a49d>] poll_freewait+0x29/0x6a
613479e8:  [<60019cd0>] maybe_map+0x30/0x9e
61347a20:  [<6001a018>] copy_chunk_from_user+0x0/0x18
61347a28:  [<60019d51>] do_op_one_page+0x13/0x61
61347a48:  [<600470e1>] local_bh_enable+0x9/0x8b
61347a68:  [<60167006>] neigh_resolve_output+0x121/0x167
61347a98:  [<60176be2>] ip_output+0x16a/0x1ae
61347ad8:  [<60176f97>] ip_queue_xmit+0x371/0x3b9
61347b08:  [<60037ecd>] setjmp_wrapper+0x82/0xd5
61347b18:  [<60185e0f>] tcp_cwnd_restart+0x1e/0xcc
61347b68:  [<6018659b>] tcp_transmit_skb+0x40d/0x437
61347b98:  [<6007cbfb>] cache_alloc_refill+0xc4/0x1a2
61347bd8:  [<60187bab>] tcp_write_xmit+0x1d1/0x241
61347c18:  [<60187c3a>] __tcp_push_pending_frames+0x1f/0x7b
61347c38:  [<6017d7ac>] tcp_sendmsg+0x9f8/0xb05
61347c40:  [<6001a0ad>] copy_chunk_to_user+0x0/0x12
61347c78:  [<6003e244>] __activate_task+0x27/0x38
61347c88:  [<60019cd0>] maybe_map+0x30/0x9e
61347cc8:  [<601589cd>] do_sock_write+0x9f/0xa4
61347cd8:  [<60158a25>] sock_aio_write+0x53/0x62
61347ce8:  [<60019f03>] do_buffer_op+0x164/0x21e
61347d58:  [<60037f13>] setjmp_wrapper+0xc8/0xd5
61347d78:  [<6007f420>] do_sync_write+0xdd/0x120
61347de8:  [<60053fa7>] autoremove_wake_function+0x0/0x2e
61347ea8:  [<6007f53c>] vfs_write+0xd9/0x182
61347ee8:  [<6007f698>] sys_write+0x45/0x6e
61347f28:  [<60019abb>] handle_syscall+0x63/0x7c
61347f48:  [<60038ec4>] handle_trap+0xcb/0xd2
61347f78:  [<60039334>] userspace+0x131/0x178
61347fd8:  [<60019808>] fork_handler+0x74/0x79


View attachment "config-2.6-uml" of type "text/plain" (12344 bytes)

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