From: Michael Tokarev Subject: Re: DIO process stuck apparently due to dioread_nolock (3.0) Date: Fri, 12 Aug 2011 19:55:00 +0400 Message-ID: <4E454CD4.3080505@msgid.tls.msk.ru> References: <4E4262A5.6030903@msgid.tls.msk.ru> <20110811115943.GF4755@quack.suse.cz> <4E43C956.3060507@msgid.tls.msk.ru> <20110811140101.GA18802@quack.suse.cz> <4E4435F4.6000406@msgid.tls.msk.ru> <4E44C6ED.2030506@msgid.tls.msk.ru> <20110812130729.GC28324@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Jiaying Zhang , linux-ext4@vger.kernel.org To: Jan Kara Return-path: Received: from isrv.corpit.ru ([86.62.121.231]:45036 "EHLO isrv.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751269Ab1HLPzE (ORCPT ); Fri, 12 Aug 2011 11:55:04 -0400 In-Reply-To: <20110812130729.GC28324@quack.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: 12.08.2011 17:07, Jan Kara wrote: [] >>>> [ 76.982985] EXT4-fs (dm-1): Unaligned AIO/DIO on inode 3407879 by oracle; performance will be poor. >>>> [ 1469.734114] SysRq : Show Blocked State >>>> [ 1469.734157] task PC stack pid father >>>> [ 1469.734473] oracle D 0000000000000000 0 6146 1 0x00000000 >>>> [ 1469.734525] ffff88103f604810 0000000000000082 ffff881000000000 ffff881079791040 >>>> [ 1469.734603] ffff880432c19fd8 ffff880432c19fd8 ffff880432c19fd8 ffff88103f604810 >>>> [ 1469.734681] ffffea000ec13590 ffffffff00000000 ffff881438c8dad8 ffffffff810eeda2 >>>> [ 1469.734760] Call Trace: >>>> [ 1469.734800] [] ? __do_fault+0x422/0x520 >>>> [ 1469.734863] [] ? ext4_file_write+0x20d/0x260 [ext4] >>>> [ 1469.734909] [] ? abort_exclusive_wait+0xb0/0xb0 >>>> [ 1469.734956] [] ? ext4_llseek+0x120/0x120 [ext4] >>>> [ 1469.734999] [] ? aio_rw_vect_retry+0x73/0x1d0 >>>> [ 1469.735039] [] ? aio_run_iocb+0x5f/0x160 >>>> [ 1469.735078] [] ? do_io_submit+0x4f8/0x600 >>>> [ 1469.735122] [] ? system_call_fastpath+0x16/0x1b [] > Probably not, just garbage on stack confuses the stack unwinder. Note > that e.g. ext4_llseek() is at the end of function as well as > abort_exclusive_wait() which probably means these functions have already > finished and just left their addresses on stack. Could you disasseble > your ext4_file_write() function and check where offset 0x20d is? Sadly you > won't see where calls are going when ext4 is compiled as a module (module > is linked when loaded into kernel) so it might be easier to compile ext4 > into the kernel and disassemble the function in vmlinux file. > >> Btw, does ext4_llseek() look sane here? Note it's called from >> aio_submit() -- does it _ever_ implement SEEKs? >> >> Maybe some debugging is neecessary here? > Yes. The trouble is I'm not completely sure where we are hanging yet. > We should know more from your disassembly. But you can try running with > attached debug patch - maybe it shows something interesting. With ext4 built-in and your patch applied: [ 429.061524] EXT4-fs (sda11): Unaligned AIO/DIO on inode 5767181 by oracle; performance will be poor. [ 429.061669] Going to wait for 18446744073709551199 aios [ 437.717942] SysRq : Show Blocked State [ 437.718109] task PC stack pid father [ 437.718528] oracle D 0000000000000000 0 3844 1 0x00000000 [ 437.718767] ffff88203e330080 0000000000000082 0000000000000000 ffff881078e3f7d0 [ 437.719156] ffff88203dc15fd8 ffff88203dc15fd8 ffff88203dc15fd8 ffff88203e330080 [ 437.719546] 0000001e0000000f 0000000000000246 205b88103f806680 3136302e39323420 [ 437.719935] Call Trace: [ 437.720043] [] ? printk+0x43/0x48 [ 437.720155] [] ? ext4_file_write+0x21d/0x290 [ 437.720267] [] ? abort_exclusive_wait+0xb0/0xb0 [ 437.720376] [] ? ext4_llseek+0x120/0x120 [ 437.720485] [] ? aio_rw_vect_retry+0x73/0x1d0 [ 437.720593] [] ? aio_run_iocb+0x5f/0x160 [ 437.720699] [] ? do_io_submit+0x4f8/0x600 [ 437.720811] [] ? system_call_fastpath+0x16/0x1b Trying to find how to disassemble things now... And yes, 18446744073709551199 aios sounds quite alot ;) Thanks, /mjt