the bitrig master branch has been updated by pedro with 1 new commit:

commit 96feb3aa4bb45cc45d25b3fd2d8c451060926339
diff: https://github.com/bitrig/bitrig/commit/96feb3a
author: pedro martelletto <[email protected]>
date: Thu Jan 1 13:50:36 2015 +0100

fix race condition in bwrite()

in bwrite(), don't inspect b_bq after calling VOP_STRATEGY() and
lowering the IPL. at that point we no longer own the buffer, so it is
possible for the issued i/o to complete between the moment we check if
b_bq is set and the subsequent call to bufq_wait(), leading to a null
pointer dereference in the latter function, as observed empirically this
morning on my amd64 running dpb -p 8.

ok patrick@ dhill@

M       sys/kern/kern_bufq.c
M       sys/kern/vfs_bio.c
M       sys/sys/buf.h

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