there is a bug in twe driver or disk subsystem for sure

Poul-Henning Kamp phk at
Fri Apr 2 12:09:02 PST 2004

In message <A1964EDB64C8094DA12D2271C04B812601532143 at>, Vinod Ka
shyap writes:
>The 3ware (twe) driver is obviously not causing this panic.
>It's something else (at line 128 in file /usr/src/sys/udm_dbg.c).

>Memory modified after free 0x788f400(508) val=20202020 @ 0xe788f400
>panic: Most recently used by devbuf
>at line 128 in file /usr/src/sys/udm_dbg.c

You're wrong vinod, the bug _is_ most likely in the 3ware driver.

What happens is that some piece of RAM is passed to free(9) and
some code subsequently writes to it.  We only discover this when
we try to reuse it next time and it doesn't contain the correct
"magic debug pattern".

Please compile your kernel with DIAGNOSTICS to enable the extended
malloc(9) debugging functions.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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