From: "홍신 shin hong" <hongshin@gmail.com>
To: linux-fsdevel@vger.kernel.org
Subject: a suspected race bug at locks_remove_flock()
Date: Fri, 24 Jul 2009 16:55:17 +0900 [thread overview]
Message-ID: <2014bcab0907240055x5292ccf2r61a3dcb137de8f91@mail.gmail.com> (raw)
Hi. I found a suspected race condition bug at locks_remove_flocks()
in fs/locks.c of recent Linux kernel.
This bug is similar to the one reported in
ChangeLog 2.6.24 (commit 85c59580b30c82aa771aa33b37217a6b6851bc14)
and also to the one I report right before.
During the execution of locks_remove_flock(),
Big Kernel Lock(BKL) might be released and re-taken
at the call site of locks_delete_lock() unintentionally
due to the Releasing-On-Block semantics of BKL.
This is because locks_delete_lock() can invoke kmem_cache_alloc()
which can be blocked.
BKL releasing an retaking may result race condition
by breaking atomic execution of the code block
guarded by lock_kernel() and unlock_kernelt().
Please examine the possbility of race condition of this code
and let me know your opinion.
Shin Hong
reply other threads:[~2009-07-24 7:55 UTC|newest]
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