Date:	Tue, 31 Jul 2007 08:53:48 +0800
From:	Joe Jin <joe.jin@...cle.com>
To:	Zach Brown <zach.brown@...cle.com>
Cc:	Badari Pulavarty <pbadari@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joe Jin <joe.jin@...cle.com>,
	gurudas pai <gurudas.pai@...cle.com>,
	torvalds@...ux-foundation.org, jens.axboe@...cle.com,
	lkml <linux-kernel@...r.kernel.org>, wen.gang.wang@...cle.com
Subject: Re: [PATCH] add check do_direct_IO() return val

> Well, I'm having a heck of a time getting this to fail.  It looks  
> possible, though.  Joe, were you guys able to narrow it down to a  
> reproducible test case?  Do you have any oops output messages from  
> the crashes?

Zach, it easy to reproduce through fio with following config file

# cat jobfile
[global]
bs=8k
iodepth=1024
iodepth_batch=60
randrepeat=1
size=1m
directory=/home/oracle
numjobs=20
[job1]
	ioengine=sync
	bs=1k
	direct=1
	rw=randread
	filename=file1:file2
[job2]
	ioengine=libaio
	rw=randwrite
	direct=1
	filename=file1:file2
[job3]
	bs=1k
	ioengine=posixaio
	rw=randwrite
	direct=1
	filename=file1:file2
[job4]
	ioengine=splice
	direct=1
	rw=randwrite
	filename=file1:file2
[job5]
	bs=1k
	ioengine=sync
	rw=randread
	filename=file1:file2
[job7]
	ioengine=libaio
	rw=randwrite
	filename=file1:file2
[job8]
	ioengine=posixaio
	rw=randwrite
	filename=file1:file2
[job9]
	ioengine=splice
	rw=randwrite
	filename=file1:file2
[job10]
	ioengine=mmap
	rw=randwrite
	bs=1k
	filename=file1:file2
[job11]
	ioengine=mmap
	rw=randwrite
	direct=1
	filename=file1:file2 



Runing fio just a short time, will get panic like following:


BUG: unable to handle kernel paging request at virtual address 23c070bf
 printing eip:
c04a07fd
*pdpt = 000000001ff88001
*pde = 0000000000000000
Oops: 0000 [#1]
SMP
Modules linked in: netconsole autofs4 hidp nfs lockd nfs_acl rfcomm l2cap
bluetooth sunrpc ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr
@ iscsi_tcp libiscsi scsi_transport_iscsi dm_mirror dm_multipath dm_mod video
sbs button battery ac ipv6 parport_pc lp parport i2c_piix4 i2c_core cfi_probe
gen_probe floppy scb2_flash sg mtdcore chipreg tg3 e1000 serio_raw ide_cd
@ cdrom aic7xxx scsi_transport_spi sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd
uhci_hcd
CPU:    0
EIP:    0060:[<c04a07fd>]    Not tainted VLI
EFLAGS: 00010293   (2.6.22 #2)
EIP is at bio_get_nr_vecs+0x0/0x30
eax: 23c07063   ebx: 00000003   ecx: ffffffff   edx: 00000000
esi: de5cef74   edi: f54a9600   ebp: 00000000   esp: de5ceca8
ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
Process fio (pid: 17820, ti=de5ce000 task=de6570e0 task.ti=de5ce000)
Stack: c04a1c9d ffffffff ffffffff 00000009 f54a9600 de5cef74 00000000 f54a9600
       c04a1f43 00000000 c04a2b46 c0460466 c2c5baa0 c0812500 c0462c0a 00000001
       00000001 df4b90d4 de5ceee4 00000011 00000001 00000009 00000009 00000000
Call Trace:
 [<c04a1c9d>] dio_new_bio+0x82/0xfe
 [<c04a1f43>] dio_send_cur_page+0x4a/0x92
 [<c04a2b46>] __blockdev_direct_IO+0xa09/0xc83
 [<c0460466>] __pagevec_free+0x14/0x1a
 [<c0462c0a>] release_pages+0x137/0x13f
 [<f8856f30>] journal_start+0xaf/0xdd [jbd]
 [<f8890fec>] ext3_direct_IO+0xfd/0x190 [ext3]
 [<f888f6af>] ext3_get_block+0x0/0xd0 [ext3]
 [<c045d803>] generic_file_direct_IO+0xe5/0x116
 [<c045d890>] generic_file_direct_write+0x5c/0x137
 [<c045e285>] __generic_file_aio_write_nolock+0x37b/0x4df
 [<c045e43e>] generic_file_aio_write+0x55/0xb3
 [<f888cfdc>] ext3_file_write+0x24/0x8f [ext3]
 [<c0481af9>] do_sync_write+0xc7/0x10a
 [<c04347d2>] check_kill_permission+0xec/0xf5
 [<c043c557>] autoremove_wake_function+0x0/0x35
 [<c0481a32>] do_sync_write+0x0/0x10a
 [<c048233e>] vfs_write+0xa8/0x154
 [<c0482a1a>] sys_pwrite64+0x48/0x5f
 [<c0404e12>] syscall_call+0x7/0xb
 [<c0620000>] xfrm_replay_timer_handler+0x3e/0x44
 =======================
Code: 89 c5 c7 44 24 14 f4 ff ff ff 74 d2 e9 b3 fe ff ff 83 7c 24 34 00 0f 84
0b ff ff ff e9 51 ff ff ff 83 c4 20 89 e8 5b 5e 5f 5d c3 <8b> 40 5c 8b 48 38
8b 81 20 01 00 00 0f b7 91 2a 01 00 00 0f b7
EIP: [<c04a07fd>] bio_get_nr_vecs+0x0/0x30 SS:ESP 0068:de5ceca8 




I have tried to trace the code, panic reason is dio->map_bh.b_bdev not init by 
direct_io_worker(). at do_direct_IO, dio_get_page() will return EFAULT at
this issue, it caused the dio->map_bh cannot init by later code and direct
return a error. but at direct_io_worker() do not handle for the error.

Thanks,
Joe



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