From owner-freebsd-alpha Tue Aug 21 4:28:40 2001 Delivered-To: freebsd-alpha@freebsd.org Received: from snipe.mail.pas.earthlink.net (snipe.mail.pas.earthlink.net [207.217.120.62]) by hub.freebsd.org (Postfix) with ESMTP id 57FC537B403 for ; Tue, 21 Aug 2001 04:28:37 -0700 (PDT) (envelope-from tlambert2@mindspring.com) Received: from mindspring.com (dialup-209.245.137.2.Dial1.SanJose1.Level3.net [209.245.137.2]) by snipe.mail.pas.earthlink.net (EL-8_9_3_3/8.9.3) with ESMTP id EAA01443; Tue, 21 Aug 2001 04:28:33 -0700 (PDT) Message-ID: <3B82460B.7DA88A3F@mindspring.com> Date: Tue, 21 Aug 2001 04:29:15 -0700 From: Terry Lambert Reply-To: tlambert2@mindspring.com X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Christian Weisgerber Cc: freebsd-alpha@freebsd.org Subject: Re: alpha problems on current References: <20010817081929.A2859@freebie.xs4all.nl> <20010817152742.B437@cicely20.cicely.de> <9lje5o$24ra$1@kemoauc.mips.inka.de> <20010818172224.A4918@cicely20.cicely.de> <9ln48d$1ml6$1@kemoauc.mips.inka.de> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-alpha@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Christian Weisgerber wrote: > > > > > - I'm seeing mysterious writes (kevent says NOTE_WRITE) to my > > > > > executables. I suspect this is a VM bug. > > > > Have you found a way to isulate when it happens? > > No. I wrote a little program that watches /bin/* through kevent(2), > but I'm uncertain how to trace this any further. The writes don't > appear to be related to any particular system activity, although > they possibly correlate with the amount of activity. Also, if I > don't run setiathome in the background I get far fewer writes. > > The only strange program crash I've seen so far has been an xlogout > dying with SEGV. What are you running in your crontab? There's a well known historical problem in VM that was often tickled by the copy on write that happens with the mmap'ed database file being modified; the Vixie cron program "updates" the record in place, which triggers this. It does the update on the (now incorrect) assumption that the pwent that it gets back is actually a pointer to a static data area in libc. I thought that this bug had been squashed a year ago, but it may be that it just went into hiding. On 3.x and early 4.x, it exhibited as a random write of a page worth of the database being spammed on top of a random file (usually, it spammed the crontab itself, but I've seen it spam other files, as well). As a hack, try killing cron, and see if it still happens; if it does, then you've at least eliminated my prime suspect. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message