[dm-devel] Strange SIGSEGV problem around dmcrypt, evms and jfs

Mon Oct 16 16:12:15 UTC 2006

Hi,

I was begining to play with dmcrypt, evms and jfs on one spare disk I 
have (currently empty and only for tests). I produced some partitions with 
evms and made volumes on them. Nothing strange, normal configuration. The 
partition layout seems ok. Then I used dmcrypt mappings on top of two of 
them to make encrypted swaps and swapon'ed them. Still everything was ok. 
Then I tested different ciphers performance by doing dmcrypt mappings on 
top of some other volume with different settings and dd'ed data from and 
to them to test the speed. Then I choosen one cipher setup and and did the 
final mapping and created and mounted  jfs on it. Then I copied one large 
(like 4GB) file on it several times to make sure everything is ok. I 
checked sha1sums and everything was indeed ok.

But then all big applications (firefox, oo2, acroread, ..., opera was the 
notable exception) couldn't start being killed by SIGSEGVs out of nowhere. 
I reproduced it two time already (after a clean reboot): today and 
yesterday. Maybe someone knows what is happening? For me it looks like 
something broken some kernel memory and the kernel started doing stupid 
things. But nothing strange has shown in logs.

One time I couldn't even shut down the machine normally, only SysRQ-B 
worked (shutdown scripts were probably killed too or something). Every 
application works ok (and did so for at least a year) before I will start 
playing with dmcrypt and jfs. I am not sure where exactly the problems 
start but will be investigating it shortly.

I am rather sure that my hardware is ok. Everything was and is fine till I 
will start doing these tests. Including that testing disk (tested with 
smart and dd and some others). My setup is:
- Athlon (Barton) XP 2000MHz
- Abit KW7 KT880 board
- 1GB DDR 133
- main disk is 80GB Samsung @ IDE (VIA southbridge)
- testing disk is 250GB Seagate @ SATA (VIA southbridge).

This behavoiur was observed on 2.6.18-ck1 + vesafb-tng patch. Kernel was 
tainted by nvidia and kqemu modules. Now I am trying to recreate this 
problem with 2.6.18.1 with nearly all kernel debuging options turned on
and without any proprietary modules loaded. But since I don't know exactly 
how to reproduce the problem it may take some time so any suggestions what 
can be wrong are welcome.

Further info available on request.

BTW. Why booting my machine with 2.6.18.1 with nearly all debuging on I 
got the following. While I am nearly sure it is not the problem I am 
writing about I will report it:

Oct 16 17:29:33 kangur [   74.485627] =============================================
Oct 16 17:29:33 kangur [   74.485767] [ INFO: possible recursive locking detected ]
Oct 16 17:29:33 kangur [   74.485840] ---------------------------------------------
Oct 16 17:29:33 kangur [   74.485912] evms_activate/2346 is trying to acquire lock:
Oct 16 17:29:33 kangur [   74.485985]  (&md->io_lock){----}, at: [<f8d95458>] dm_request+0x18/0x150 [dm_mod]
Oct 16 17:29:33 kangur [   74.486269]
Oct 16 17:29:33 kangur [   74.486270] but task is already holding lock:
Oct 16 17:29:33 kangur [   74.486406]  (&md->io_lock){----}, at: [<f8d95458>] dm_request+0x18/0x150 [dm_mod]
Oct 16 17:29:33 kangur [   74.486673]
Oct 16 17:29:33 kangur [   74.486674] other info that might help us debug this:
Oct 16 17:29:33 kangur [   74.486813] 1 lock held by evms_activate/2346:
Oct 16 17:29:33 kangur [   74.486883]  #0:  (&md->io_lock){----}, at: [<f8d95458>] dm_request+0x18/0x150 [dm_mod]
Oct 16 17:29:33 kangur [   74.487191]
Oct 16 17:29:33 kangur [   74.487192] stack backtrace:
Oct 16 17:29:33 kangur [   74.487475]  [<c01043ad>] show_trace_log_lvl+0x18d/0x1b0
Oct 16 17:29:33 kangur [   74.487606]  [<c0104af2>] show_trace+0x12/0x20
Oct 16 17:29:33 kangur [   74.487728]  [<c0104b59>] dump_stack+0x19/0x20
Oct 16 17:29:33 kangur [   74.487851]  [<c0136193>] __lock_acquire+0x813/0xd80
Oct 16 17:29:33 kangur [   74.488044]  [<c0136a65>] lock_acquire+0x75/0xa0
Oct 16 17:29:33 kangur [   74.488230]  [<c013298a>] down_read+0x3a/0x50
Oct 16 17:29:33 kangur [   74.488413]  [<f8d95458>] dm_request+0x18/0x150 [dm_mod]
Oct 16 17:29:33 kangur [   74.488543]  [<c0211517>] generic_make_request+0x147/0x1c0
Oct 16 17:29:33 kangur [   74.489020]  [<f8d9443d>] __map_bio+0x4d/0xa0 [dm_mod]
Oct 16 17:29:33 kangur [   74.489141]  [<f8d9517a>] __split_bio+0x34a/0x380 [dm_mod]
Oct 16 17:29:33 kangur [   74.489263]  [<f8d95514>] dm_request+0xd4/0x150 [dm_mod]
Oct 16 17:29:33 kangur [   74.489384]  [<c0211517>] generic_make_request+0x147/0x1c0
Oct 16 17:29:33 kangur [   74.489745]  [<c0213bc2>] submit_bio+0x72/0x120
Oct 16 17:29:33 kangur [   74.490112]  [<c016ee8a>] submit_bh+0xca/0x120
Oct 16 17:29:33 kangur [   74.490358]  [<c0171f58>] block_read_full_page+0x258/0x2d0
Oct 16 17:29:33 kangur [   74.490602]  [<c0174ecf>] blkdev_readpage+0xf/0x20
Oct 16 17:29:33 kangur [   74.490851]  [<c0154740>] __do_page_cache_readahead+0x1b0/0x260
Oct 16 17:29:33 kangur [   74.491071]  [<c0154852>] blockable_page_cache_readahead+0x62/0xe0
Oct 16 17:29:33 kangur [   74.491288]  [<c0154a9d>] page_cache_readahead+0x11d/0x1d0
Oct 16 17:29:33 kangur [   74.491504]  [<c014e6b2>] do_generic_mapping_read+0x462/0x4e0
Oct 16 17:29:33 kangur [   74.491718]  [<c014f0de>] __generic_file_aio_read+0xee/0x220
Oct 16 17:29:33 kangur [   74.491929]  [<c015048d>] generic_file_read+0x8d/0xb0
Oct 16 17:29:33 kangur [   74.492141]  [<c016d94d>] vfs_read+0xad/0x180
Oct 16 17:29:33 kangur [   74.492377]  [<c016ddbd>] sys_read+0x3d/0x70
Oct 16 17:29:33 kangur [   74.492616]  [<c01030ed>] sysenter_past_esp+0x56/0x8d
Oct 16 17:29:33 kangur [   74.492736]  [<b7f19410>] 0xb7f19410

Thanks in advance,

Grzegorz Kulewski