Date: Fri, 15 May 2009 13:17:09 -0400 From: Ben Kelly <ben@wanderview.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: [patch] corrupt memstat_kvm_malloc(3) output and dtrace Message-ID: <6A55FF0C-EEE2-473A-867C-489E3F18463D@wanderview.com> In-Reply-To: <200905121028.58998.jhb@freebsd.org> References: <9A637B27-7C89-49BA-8385-A5B2D5D54BB3@wanderview.com> <EE174440-B065-40FE-8AAC-4FAFF4B782B4@wanderview.com> <200905121028.58998.jhb@freebsd.org>
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On May 12, 2009, at 10:28 AM, John Baldwin wrote: > On Wednesday 06 May 2009 1:00:09 am Ben Kelly wrote: >> On May 5, 2009, at 10:18 AM, Ben Kelly wrote: >>> While debugging a problem recently with Alexander Leidinger we >>> noticed that crashinfo(8) was producing corrupt vmstat -m output. >>> After doing some digging it appears that memstat_kvm_malloc(3) might >>> have been broken by this commit: >>> >>> http://svn.freebsd.org/viewvc/base?view=revision&revision=179222 >>> >>> The problem is that memstat_kvm_malloc(3) assumes that >>> malloc_type_internal starts with an array of malloc_types_stats >>> structures. This assumption is no longer true, though, as >>> mti_probes was inserted at the start of the structure. >>> >>> It appears that this (untested) patch might fix the problem: >>> >>> http://www.wanderview.com/svn/public/misc/zfs/vmstat_kvm_malloc.diff >>> >>> I'm not very familiar with dtrace, though. Does anyone know if this >>> would cause problems? >> >> Just FYI, I was able to recompile and test this patch tonight. It >> seems to have fixed vmstat -M $core -m output on my machine. > > I think that it would be better to update memstat_kvm_malloc(3) > though. I'm > also curious why libmemstat isn't just using malloc_types_internal > directly. I've updated the patch so that memstat_kvm_malloc(3) uses the malloc_type_internal definition to find the start of the statistics array. This also appears to fix the problem on my server. Thanks. - Ben
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