Date: Tue, 10 Nov 1998 15:43:27 +1030 From: Greg Lehey <grog@lemis.com> To: Alexander Litvin <archer@lucky.net>, Luoqi Chen <luoqi@watermarkgroup.com> Cc: current@FreeBSD.ORG Subject: Re: The infamous dying daemons bug Message-ID: <19981110154327.X499@freebie.lemis.com> In-Reply-To: <199811100136.DAA00563@grape.carrier.kiev.ua>; from Alexander Litvin on Tue, Nov 10, 1998 at 03:36:28AM %2B0200 References: <199811092056.PAA22043@lor.watermarkgroup.com> <199811100136.DAA00563@grape.carrier.kiev.ua>
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On Tuesday, 10 November 1998 at 3:36:28 +0200, Alexander Litvin wrote:
> In article <199811092056.PAA22043@lor.watermarkgroup.com> you wrote:
>>> Totally unrelated to the problem. It seems, so far as I was able to
>>> characterize, to happen to daemons which are *swapped out* at the time
>>> of the memory shortage. If it's active enough to still be in core, it
>>> doesn't get spammed.
>>>
> LC> I went through swap_pager.c today and found a problem that could potentially
> LC> have bad consequences. It's a comparison between page index in the swap pager
> LC> and the size of the vm object, since a shadowed object may have a non-zero
> LC> paging offset with respect to the swap pager, the comparison should have taken
> LC> the offset into account. This piece of code has been there since '95, so
> LC> I can't say if this was responsible for the daemon dying problem.
>
> It is definitely not responsible. At least for this particular problem,
> though it may fix something else ;)
>
> After applying the patch, and artificially exhausting memory, I promptly
> got:
>
> Nov 10 03:15:34 grape /kernel: swap_pager: suggest more swap space: 61 MB
> Nov 10 03:16:26 grape /kernel: pid 310 (sendmail), uid 0: exited on signal 11
> Nov 10 03:17:26 grape /kernel: pid 311 (sendmail), uid 0: exited on signal 11
> Nov 10 03:18:25 grape /kernel: pid 313 (sendmail), uid 0: exited on signal 11
> Nov 10 03:19:25 grape /kernel: pid 353 (sendmail), uid 0: exited on signal 11
> Nov 10 03:20:26 grape /kernel: pid 394 (sendmail), uid 0: exited on signal 11
Ah, now that's one that I've been getting without exhausting memory.
I'm assuming that these dying sendmails are children of the daemon.
What happens when you kill -1 the daemon ("accepting connections on
port 25 (sendmail)")? In my experience, it *always* dies with a
SIGSEGV after these messages have occurred.
Greg
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