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From: Greg KH on 30 Mar 2010 20:50
2.6.27-stable review patch. If anyone has any objections, please let us know.
From: Robert Varga <nite(a)hq.alert.sk>
commit 657e9649e745b06675aa5063c84430986cdc3afa upstream.
I have recently came across a preemption imbalance detected by:
<4>huh, entered ffffffff80644630 with preempt_count 00000102, exited with 00000101?
<0>------------[ cut here ]------------
<2>kernel BUG at /usr/src/linux/kernel/timer.c:664!
<0>invalid opcode: 0000  PREEMPT SMP
with ffffffff80644630 being inet_twdr_hangman().
This appeared after I enabled CONFIG_TCP_MD5SIG and played with it a
bit, so I looked at what might have caused it.
One thing that struck me as strange is tcp_twsk_destructor(), as it
calls tcp_put_md5sig_pool() -- which entails a put_cpu(), causing the
detected imbalance. Found on 184.108.40.206, but 2.6.31 is affected as well,
as far as I can tell.
Signed-off-by: Robert Varga <nite(a)hq.alert.sk>
Signed-off-by: David S. Miller <davem(a)davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>
net/ipv4/tcp_minisocks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
@@ -362,7 +362,7 @@ void tcp_twsk_destructor(struct sock *sk
struct tcp_timewait_sock *twsk = tcp_twsk(sk);
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