Date: Sun, 26 Dec 2004 16:47:59 -0800 From: Kris Kennaway <kris@obsecurity.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: Occasional wedging entering DDB via serial break Message-ID: <20041227004759.GA57634@xor.obsecurity.org> In-Reply-To: <Pine.NEB.3.96L.1041226223521.46391E-100000@fledge.watson.org> References: <Pine.NEB.3.96L.1041226223521.46391E-100000@fledge.watson.org>
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--liOOAslEiF7prFVr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Dec 26, 2004 at 10:37:32PM +0000, Robert Watson wrote: >=20 > I'm seeing occasional wedging attempting to enter DDB via a serial break > on a dual-Xeon box (4 logical processors). The symptoms usually look > something like this: >=20 > hippy# ./tmp.csh > ~KDB: enter: Line break on console > [thread pid 560 tid 100202 ] > Stopped at kdb_enter+0x2c: leave > db> show alllocks > db> cont > load: 0.04 cmd: super-smack 619 [runnable] 0.02u 0.51s 2% 2216k > ~KDB: enter: Line break on console > [thread pid 560 tid 100201 ] > Stopped at kdb_enter+0x2c: leave > db> show alllocks > Process 560 (mysqld) > Thread 0x18769 > exclusive sleep mutex so_rcv r =3D 0 (0xc2a25bcc) locked @ > kern/uipc_usrreq.c:464 > exclusive sleep mutex unp r =3D 0 (0xc091a740) locked @ > kern/uipc_usrreq.c:392 > db> cont > load: 0.92 cmd: super-smack 619 [runnable] 0.05u 1.36s 6% 2216k > ~KDB: enter: Line break on console > [thread pid 560 tid 100199 ] > Stopped at kdb_enter+0x2c: leave > db> show alllocks > db> cont > load: 2.12 cmd: super-smack 616 [running] 0.08u 2.90s 10% 2216k > ~KDB: enter: Line break on console > <wedge> >=20 > After that point, a serial break will no longer drop to DDB, respond to > pings, etc. The box is running 6.x-CURRENT from this morning. Is anyone > else seeing this, or does anyone else have ideas about what might cause > this? I see much the same..it seems to be just one more way in which DDB is broken on SMP machines. Setting debug.kdb.stop_cpus=3D0 tends to fix this for me, but then I get the joy of overlapping panics from multiple CPUs. Kris --liOOAslEiF7prFVr Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (FreeBSD) iD8DBQFBz1u/Wry0BWjoQKURAvn9AKDEIprV38dRcL710zE01/+piVrUDgCgkxTc mpZV5mVVCFDq5kVed82CqWk= =jnDR -----END PGP SIGNATURE----- --liOOAslEiF7prFVr--
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