From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: BUG() in 2.4: sg direct IO + exit() Date: Wed, 24 Mar 2004 22:57:42 +1000 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <406185C6.6050705@torque.net> References: <04Mar23.100431est.332209@cyborg.cybernetics.com> Reply-To: dougg@torque.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from bunyip.cc.uq.edu.au ([130.102.2.1]:28682 "EHLO bunyip.cc.uq.edu.au") by vger.kernel.org with ESMTP id S263328AbUCXM5G (ORCPT ); Wed, 24 Mar 2004 07:57:06 -0500 In-Reply-To: <04Mar23.100431est.332209@cyborg.cybernetics.com> List-Id: linux-scsi@vger.kernel.org To: tonyb@cybernetics.com Cc: linux-scsi@vger.kernel.org Tony Battersby wrote: > The following BUG() is triggered in 2.4.x when a program calls exit() > immediately after sending a SCSI command that uses direct IO: > > kernel BUG at page_alloc.c:98! > invalid operand: 0000 > sg sym53c8xx_2 e1000 > CPU: 0 > EIP: 0010:[] Not tainted > EFLAGS: 00010202 > EIP is at __free_pages_ok+0x32/0x2b0 [kernel] > eax: 00000001 ebx: c12aceb0 ecx: c12aceb0 edx: 00000000 > esi: 00000000 edi: 00000000 ebp: 00000001 esp: c02bbe94 > ds: 0018 es: 0018 ss: 0018 > Process swapper (pid: 0, stackpage=c02bb000) > Stack: cfefc640 cfdf2de8 cfbe93c0 cfefc600 00000001 00000000 cfefc600 > c12aceb0 > cf926fa0 00000000 cfb8b040 c0127cb0 cfb8b04c cfb8b04c cfb8b000 > d0885db6 > cf926fa0 00000000 cfb8b040 d0885cc9 cfb8b04c 00000001 cfd08680 > cfd086c8 > Call Trace: > [] unmap_kiobuf+0x30/0x50 [kernel] > [] sg_unmap_and+0x26/0x50 [sg] > [] sg_finish_rem_req+0x39/0x70 [sg] > [] sg_cmd_done_bh+0x281/0x380 [sg] > [] scsi_finish_command+0xda/0xe0 [kernel] > [] scsi_bottom_half_handler+0xc0/0x230 [kernel] > [] bh_action+0x4b/0x90 [kernel] > [] tasklet_hi_action+0x61/0xa0 [kernel] > [] do_softirq+0x6b/0xd0 [kernel] > [] do_IRQ+0xdf/0xf0 [kernel] > [] default_idle+0x0/0x40 [kernel] > [] default_idle+0x0/0x40 [kernel] > [] call_do_IRQ+0x5/0xd [kernel] > [] default_idle+0x0/0x40 [kernel] > [] default_idle+0x0/0x40 [kernel] > [] default_idle+0x2c/0x40 [kernel] > [] cpu_idle+0x52/0x70 [kernel] > [] stext+0x0/0x50 [kernel] > > Code: 0f 0b 62 00 ab 04 23 c0 89 d8 e8 2f ed ff ff 8b 7b 28 85 ff > <0>Kernel panic: Aiee, killing interrupt handler! > In interrupt handler - not syncing > > The following program reproduces the problem: > > #include > #include > #include > #include > #include > #include > #include > #include > #include > > unsigned char mode_sense_cdb[] = { 0x1a, 0x00, 0x3f, 0x00, 0xff, 0x00 }; > > int main(int argc, char *argv[]) > { > int fd; > unsigned char sense_data[256]; > unsigned char buf[256]; > sg_io_hdr_t io; > > fd = open("/dev/sg0", O_RDWR); > if (fd == -1) { > perror("open(/dev/sg0)"); > exit(1); > } > > memset(&io, 0, sizeof(sg_io_hdr_t)); > io.interface_id = 'S'; > io.timeout = UINT_MAX; > io.flags = SG_FLAG_DIRECT_IO; > io.sbp = sense_data; > io.mx_sb_len = 0xff; > io.cmdp = mode_sense_cdb; > io.cmd_len = 6; > io.dxfer_direction = SG_DXFER_FROM_DEV; > io.dxferp = buf; > io.dxfer_len = 0xff; > write(fd, &io, sizeof(sg_io_hdr_t)); > > return 0; > } > > Just compile, echo 1 > /proc/scsi/sg/allow_dio, and run. The SCSI > device that I am using is a tape drive, but it shouldn't matter. > > I have tested this with 2.4.21+kksymoops and 2.4.26-pre5+kksymoops with > the same results. The above stack trace is from 2.4.26-pre5. I haven't > tried 2.6. > > I am running a SMP kernel on a UP Intel P4 with 256 MB RAM. The test > machine does not have any swap space configured (swapoff -a). Tony, It is not causing an oops when I try with scsi_debug and lk 2.6.5-rc2. Neither is there a problem with a Suse 9 stock SMP kernel (2.4.21-99-smp4G) on an old dual celeron (A-bit mb) box with a Sony SDT-7000 tape drive on /dev/sg0. I'll keep looking. The oops suggests that the memory is not being locked down (as you are probably aware). Doug Gilbert