sysctl -a panic on VIMAGE kernels
Gleb Smirnoff
glebius at FreeBSD.org
Sun Aug 9 10:36:41 UTC 2015
On Sun, Aug 09, 2015 at 12:28:22PM +0200, Kristof Provost wrote:
K> Hi,
K>
K> I’ve run into a reproducible panic on a VIMAGE kernel with ‘sysctl -a’.
K>
K> Relevant backtrace bits:
K> #8 0xffffffff80e7dd28 in trap (frame=0xfffffe01f16b26a0)
K> at /usr/src/sys/amd64/amd64/trap.c:426
K> #9 0xffffffff80e5e6a2 in calltrap ()
K> at /usr/src/sys/amd64/amd64/exception.S:235
K> #10 0xffffffff80cea67d in uma_zone_get_cur (zone=0x0)
K> at /usr/src/sys/vm/uma_core.c:3006
K> #11 0xffffffff80cec029 in sysctl_handle_uma_zone_cur (
K> oidp=0xffffffff818a7c90, arg1=0xfffffe00010c0438, arg2=0,
K> req=0xfffffe01f16b2868) at /usr/src/sys/vm/uma_core.c:3580
K> #12 0xffffffff80a28614 in sysctl_root_handler_locked (oid=0xffffffff818a7c90,
K> arg1=0xfffffe00010c0438, arg2=0, req=0xfffffe01f16b2868)
K> at /usr/src/sys/kern/kern_sysctl.c:183
K> #13 0xffffffff80a27d70 in sysctl_root (arg1=<value optimized out>,
K> arg2=<value optimized out>) at /usr/src/sys/kern/kern_sysctl.c:1694
K> #14 0xffffffff80a28372 in userland_sysctl (td=0x0, name=0xfffffe01f16b2930,
K> namelen=<value optimized out>, old=<value optimized out>,
K> oldlenp=<value optimized out>, inkernel=<value optimized out>,
K> new=<value optimized out>, newlen=<value optimized out>,
K> retval=<value optimized out>, flags=0)
K> at /usr/src/sys/kern/kern_sysctl.c:1798
K> #15 0xffffffff80a28144 in sys___sysctl (td=0xfffff8000b1e49a0,
K> uap=0xfffffe01f16b2a40) at /usr/src/sys/kern/kern_sysctl.c:1724
K>
K> In essence, what happens is that we end up in sysctl_handle_uma_zone_cur() and arg1 is a pointer to NULL,
K> so we call uma_zone_get_cur(zone); with zone == NULL.
K>
K> There’s been a bit of churn around tcp_reass_zone, and I think the latest version is wrong.
K> It marks the sysctl as CTLFLAG_VNET, but the exposed variable is not VNET_DEFINE().
K>
K> The following fixes it for me:
K>
K> diff --git a/sys/netinet/tcp_reass.c b/sys/netinet/tcp_reass.c
K> index 77d8940..3913ef3 100644
K> --- a/sys/netinet/tcp_reass.c
K> +++ b/sys/netinet/tcp_reass.c
K> @@ -84,7 +84,7 @@ SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
K> "Global maximum number of TCP Segments in Reassembly Queue");
K>
K> static uma_zone_t tcp_reass_zone;
K> -SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_VNET,
K> +SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
K> &tcp_reass_zone,
K> "Global number of TCP Segments currently in Reassembly Queue”);
Right, if a variable isn't virtualized, the CTLFLAG_VNET must be removed.
Patrick, how is your progress wuth improved reassembly?
--
Totus tuus, Glebius.
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