Date: Mon, 31 May 1999 21:13:49 -0400 (EDT) From: Thomas David Rivers <rivers@dignus.com> To: FreeBSD-gnats-submit@freebsd.org Subject: kern/11969: VM_fault with mmap'd CDROM data. Message-ID: <199906010113.VAA00620@lakes.dignus.com>
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>Number: 11969 >Category: kern >Synopsis: VM_fault with mmap'd CDROM data. >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Mon May 31 18:20:01 PDT 1999 >Closed-Date: >Last-Modified: >Originator: Thomas David Rivers >Release: FreeBSD 3.1-RELEASE i386 >Organization: Dignus, LLC >Environment: FreeBSD lakes.dignus.com 3.1-RELEASE FreeBSD 3.1-RELEASE #0: Sat Mar 6 17:34:47 EST 1999 rivers@lakes.dignus.com:/usr/src/sys/compile/LAKES i386 Pentium 150 - 32 meg of memory, AHA2940 SCSI card, HP 6020i CDROM. >Description: Sometimes, when using cmp(1) or cp(1) on data read from a CD, I encounter the following: May 31 21:07:20 lakes su: rivers to root on /dev/ttyp2 (cd0:ahc0:0:4:0): READ(10). CDB: 28 0 0 2 9b dc 0 0 1 0 (cd0:ahc0:0:4:0): VOLUME OVERFLOW info:29bdc asc:aa,0 (cd0:ahc0:0:4:0): Vendor Specific ASC (cd0:ahc0:0:4:0): cddone: got error 0x5 back vm_fault: pager read error, pid 388 (cmp) May 31 21:07:33 lakes /kernel: pid 388 (cmp), uid 500: exited on signal 11 However, cat(1) will read the data just fine, and it seems to be correct. I believe cmp(1) and cp(1) both mmap() the source files, whilc cat(1) does not - does this imply mmap()ing CD-ROM data has a problem? Also - after encountering this, an umount of the CD-ROM will panic and crash the system. >How-To-Repeat: The easiest thing I've found for repeating this is to cut your own CD from a large file system. Then, run the following shell script to compare all the files (<src> is the source directory of the written CD, /cdrom is where the CD-ROM is mounted): cd <src> for i in `find . -print` do if test -f $i then cmp $i /cdrom/$i fi done Sometimes, you'll get a Segmentation Fault from cmp. A cp(1) on the troublesome file will give you the error "Bad Address". >Fix: ??? >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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