Hi,
I've recently tested ext4 in user mode linux VM. I compiled linux
2.6.36(from debian source package). I configured kernel this way ...
only disabled modules (to work with default debootstraped debian). Then
I created this script:
#!/bin/bash
DD="dd if=/dev/zero bs=1k"
for i in `seq 1 1000`; do
A=$(($RANDOM%50000))
$DD count=$A of=frag_$A
for i in `seq 1 100`; do
A=$(($RANDOM%50000))
rm -f frag_$A
done
done
This script I'had run on mounted ext4 partition (/dev/ubda ->
/mnt/test). It's purpose is creating fragmented filesystem to test
e4defrag. But after some time it hungs the whole virtual system. All
processes which want to write to /mnt/test are still in D state. I
issued sysrq t via uml_mconsole and in that output I found traces below.
Ondra
flush-98:16 D 0000000041a0d8b3 0 811 2 0x00000000
67c57d80 60276e90 69857980 6002a1ed 69857990 60013597 67c578c0 69856000
69856000 67c578c0 698579f0 601d3181 69857a10 601d74a0 698579f0
69856000
ffffffff00000a57 62e09800 00000000 69ab1480 69856000 69857a58
69857aa0 6012274e
Call Trace:
69857958: [<6002a1ed>] dequeue_task+0x39/0x48
69857968: [<60013597>] _switch_to+0x5e/0xae
69857998: [<601d3181>] schedule+0x274/0x2ae
698579f8: [<6012274e>] start_this_handle+0x2f4/0x395
69857a50: [<60042f42>] autoremove_wake_function+0x0/0x34
69857aa8: [<6012297c>] jbd2__journal_start+0xb9/0xf7
69857af8: [<601229c8>] jbd2_journal_start+0xe/0x10
69857b08: [<6010abe5>] ext4_journal_start_sb+0xe0/0x125
69857b28: [<600fa802>] ext4_meta_trans_blocks+0x5b/0xaf
69857b68: [<60100a43>] ext4_da_writepages+0x249/0x479
69857c58: [<6005b042>] do_writepages+0x1c/0x25
69857c68: [<600908bc>] writeback_single_inode+0x93/0x1d4
69857c98: [<60090c4e>] writeback_sb_inodes+0xa1/0xfe
69857cf8: [<60091364>] writeback_inodes_wb+0xc5/0xe4
69857d00: [<60042f76>] wake_bit_function+0x0/0x2e
69857d48: [<600914f2>] wb_writeback+0x16f/0x1de
69857da8: [<601d3189>] schedule+0x27c/0x2ae
69857df8: [<60091674>] wb_do_writeback+0x113/0x130
69857e08: [<601d3400>] schedule_timeout+0x13e/0x15c
69857e78: [<6009171a>] bdi_writeback_thread+0x89/0x13f
69857eb0: [<60091691>] bdi_writeback_thread+0x0/0x13f
69857ed0: [<60091691>] bdi_writeback_thread+0x0/0x13f
69857ee8: [<60042c99>] kthread+0x91/0x99
69857f48: [<60021329>] run_kernel_thread+0x41/0x4a
69857f58: [<60042c08>] kthread+0x0/0x99
69857f98: [<60021310>] run_kernel_thread+0x28/0x4a
69857fc8: [<6001350f>] new_thread_handler+0x71/0x9b
jbd2/ubdb-8 D 0000000041a0d8b3 0 4542 2 0x00000000
6838d640 60276e90 68275ca0 6002a1ed 68275cb0 60013597 6838d180 68274000
68274000 6838d180 68275d10 601d3181 68fd7470 601d74a0 68275d10
68274000
00000000 62e09800 69ab1480 1000077f1 68274000 69ab1518 68275e50
60122d7b
Call Trace:
68275c78: [<6002a1ed>] dequeue_task+0x39/0x48
68275c88: [<60013597>] _switch_to+0x5e/0xae
68275cb8: [<601d3181>] schedule+0x274/0x2ae
68275d18: [<60122d7b>] jbd2_journal_commit_transaction+0x16c/0xe59
68275d98: [<600245e3>] switch_threads+0x2d/0x3d
68275de0: [<60042f42>] autoremove_wake_function+0x0/0x34
68275df8: [<600222bb>] set_signals+0x1c/0x2e
68275e18: [<60043094>] finish_wait+0x64/0x6f
68275e58: [<60126168>] kjournald2+0xb8/0x1bb
68275e90: [<60042f42>] autoremove_wake_function+0x0/0x34
68275eb0: [<601260b0>] kjournald2+0x0/0x1bb
68275ed0: [<601260b0>] kjournald2+0x0/0x1bb
68275ee8: [<60042c99>] kthread+0x91/0x99
68275f48: [<60021329>] run_kernel_thread+0x41/0x4a
68275f58: [<60042c08>] kthread+0x0/0x99
68275f98: [<60021310>] run_kernel_thread+0x28/0x4a
68275fc8: [<6001350f>] new_thread_handler+0x71/0x9b
dd D 0000000041a0d8b3 0 4952 4593 0x00000000
6838c8c0 67c57d80 67c578f8 60284440 69b6d7a8 60013597 6838c400 69b6c000
69b6c000 6838c400 69b6d808 601d3181 69b6d7c8 6002a34f 69b6d808
69b6c000
00001000 6838c400 696c0838 00000001 ffffffffffffffff 00000000
69b6d868 601d43a2
Call Trace:
69b6d780: [<60013597>] _switch_to+0x5e/0xae
69b6d7b0: [<601d3181>] schedule+0x274/0x2ae
69b6d7c0: [<6002a34f>] wake_up_process+0x10/0x12
69b6d810: [<601d43a2>] rwsem_down_failed_common+0xb8/0xd8
69b6d838: [<600222bb>] set_signals+0x1c/0x2e
69b6d870: [<601d43e9>] rwsem_down_read_failed+0x12/0x14
69b6d880: [<60027b98>] call_rwsem_down_read_failed+0x14/0x24
69b6d8c8: [<601d3b97>] down_read+0x11/0x13
69b6d8d8: [<600fe1cc>] ext4_map_blocks+0x3e/0x18e
69b6d938: [<600ffe02>] ext4_da_get_block_prep+0x83/0x2bd
69b6d958: [<60095705>] alloc_buffer_head+0x18/0x6c
69b6d968: [<60095d31>] alloc_page_buffers+0x75/0xd1
69b6d9d8: [<60097105>] block_prepare_write+0x177/0x380
69b6d9e8: [<6005588b>] add_to_page_cache_locked+0xbf/0xe7
69b6da00: [<600ffd7f>] ext4_da_get_block_prep+0x0/0x2bd
69b6da98: [<600973f3>] __block_write_begin+0x12/0x14
69b6daa8: [<600ffa62>] ext4_da_write_begin+0x123/0x1b4
69b6db28: [<60054ca0>] generic_file_buffered_write+0x124/0x27e
69b6dbc8: [<6008889e>] file_update_time+0x3b/0xfe
69b6dc18: [<60056634>] __generic_file_aio_write+0x380/0x3bf
69b6dcd8: [<600566cb>] generic_file_aio_write+0x58/0xa2
69b6dd18: [<600f7f07>] ext4_file_write+0x92/0xa3
69b6dd48: [<60077a27>] do_sync_write+0xd1/0x10e
69b6ddb8: [<60015daf>] buffer_op+0xab/0xc7
69b6de68: [<600783fb>] vfs_write+0xb5/0x169
69b6dea8: [<60078568>] sys_write+0x45/0x6c
69b6dee8: [<60015ab8>] handle_syscall+0x58/0x70
69b6df08: [<60024ecb>] userspace+0x2dd/0x38a
69b6dfc8: [<60013497>] fork_handler+0x62/0x69
bash D 0000000041a0d8b3 0 5324 5271 0x00000002
67e2c540 60276e90 67dcfbd0 6002a1ed 67dcfbe0 60013597 67e2c080 67dce000
67dce000 67e2c080 67dcfc40 601d3181 62a31000 601d74a0 67dcfc40
67dce000
67dcfc10 62e09800 00000000 69ab1480 67dce000 67dcfca8 67dcfcf0
6012274e
Call Trace:
67dcfba8: [<6002a1ed>] dequeue_task+0x39/0x48
67dcfbb8: [<60013597>] _switch_to+0x5e/0xae
67dcfbe8: [<601d3181>] schedule+0x274/0x2ae
67dcfc48: [<6012274e>] start_this_handle+0x2f4/0x395
67dcfca0: [<60042f42>] autoremove_wake_function+0x0/0x34
67dcfcf8: [<6012297c>] jbd2__journal_start+0xb9/0xf7
67dcfd48: [<601229c8>] jbd2_journal_start+0xe/0x10
67dcfd58: [<6010abe5>] ext4_journal_start_sb+0xe0/0x125
67dcfd60: [<6008424f>] filldir+0x0/0x11a
67dcfdb8: [<600fb08a>] ext4_dirty_inode+0x1b/0x48
67dcfdd8: [<60091027>] __mark_inode_dirty+0x29/0x199
67dcfdf8: [<60088a63>] touch_atime+0x102/0x125
67dcfe38: [<6008424f>] filldir+0x0/0x11a
67dcfe48: [<600844fd>] vfs_readdir+0x7a/0xa1
67dcfe98: [<6008469d>] sys_getdents+0x90/0x124
67dcfee8: [<60015ab8>] handle_syscall+0x58/0x70
67dcff08: [<60024ecb>] userspace+0x2dd/0x38a
67dcffc8: [<60013497>] fork_handler+0x62/0x69
--
Ondřej Kunc
správce serverové farmy
CZOL media interactive s.r.o.
Sídlo: Moulíkova 2238/1, Praha 5, 15000
Kanceláře: Na Moráni 5357, Chomutov, 43001
Telefon: +420 723 137 981
E-mail: ondra@xxxxxxx
URL: www.czol.eu, www.cz-hosting.com
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