panic after removing usb flash disk

Bob Johnson fbsdlists at
Fri Aug 17 13:02:40 PDT 2007

On 8/17/07, Svein Halvor Halvorsen <svein.h at> wrote:
> Oliver Fromme wrote:
> > Roman Bogorodskiy wrote:
> >  > Artem Kuchin wrote:
> >  > > [FreeBSD crashes when a mounted device disappears]
> >  >
> >  > It's not a bug, it's a feature.
> >
> > I certainly wouldn't call it a feature.  As others have
> > noted, it is a known shortcoming in FreeBSD, and fixing
> > it is non-trivial.
> Could someone point me in some general direction, as to where I
> could learn more about the path a read/write request will take
> through all the different kernel layers? I doubt I will be able to
> fix anything, but it would be interesting to learn.

Aside from the general "RTFS", there are probably two (or three) good
places to look:

"The Design and Implementation of the FreeBSD Operating System" by
McKusick and Neville-Neil, or its predecessor which may be much more
affordable, "The Design and Implementation of the 4.4 BSD Operating
System" by McKusick, Bostic, Karels, and Quarterman.

Chapter 2 of the latter is available at
.  It will give you some hints, but probably not as much detail as you

And, of course, reading the archived threads on the topic, already
referenced by others, will provide a quick education in the issues
involved. I think that would be the best place to start.

- Bob

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