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Date:      Thu, 15 Feb 2018 10:31:13 +0100
From:      Michael Schuster <michaelsprivate@gmail.com>
To:        Per olof Ljungmark <peo@nethead.se>
Cc:        FreeBSD Mailing List <freebsd-questions@freebsd.org>
Subject:   Re: which limit is hit here?
Message-ID:  <CADqw_gKOr9va7-ffzVJYm4=kL=8m1PLGkqhY7AOQdpdgDNo_Tw@mail.gmail.com>
In-Reply-To: <e29cfb8e-c199-4b5c-7580-71646c807a52@nethead.se>
References:  <d4d1093d-0db2-baed-0fb5-04b5127c8ccb@nethead.se> <CADqw_gKS=%2Be=PCgG6OJVfbuSwWD4zioZ__gnVNc5hYtM2Mfo%2Bg@mail.gmail.com> <71635f3b-0494-1956-fa31-bd8df7b72a93@nethead.se> <CADqw_g%2BQ0=jbqD9wnYnprXtrUvcz5Lg8AHGMmNrHO8K-UthOgQ@mail.gmail.com> <e29cfb8e-c199-4b5c-7580-71646c807a52@nethead.se>

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On Thu, Feb 15, 2018 at 10:27 AM, Per olof Ljungmark <peo@nethead.se> wrote:

>
>
> On 02/15/18 10:07, Michael Schuster wrote:
> > hmm ...
> >
> > what does gdb's "info shared" print out?
>
> "No shared libraries loaded at this time."
>

is that really all?

 I'd expect something like this (library names removed by me) - this is not
on BSD, btw, but I'd expect gdb to behave in a similar fashion:

(gdb) info shared
>From        To          Syms Read   Shared Object Library
0x01120000  0x011b090c  Yes         xxxx
0x78a3e000  0x78a64660  Yes (*)     xxxxxx
0x78317000  0x7831d290  Yes (*)     xxxxxx.so
0x78087000  0x78087000  No          xxxxxxxxxxxx.so.1.1
0x78056000  0x78056000  No          xxxxxxxxxx.1.2
0x7801f000  0x7801f000  No          xxxxxxxxxxxxso.1.0
0x7800c000  0x7800c000  No          xxxxxxxxxx.so.1.0
0x78000000  0x78000000  No          xxxxxxxxxxxxxx.so.1.0
0x78017000  0x78017000  No          xxxxxxxxx.so.1.0
0x78129000  0x7819f960  Yes         xxxxxxso
0x78037000  0x78040768  Yes         xxxxxxxx.so
0x78025000  0x7802f6e0  Yes         xxxxxxxxso.2
0x78047000  0x78054970  Yes         xxxxxxxxxxx.so
(*): Shared library is missing debugging information.
(gdb)



>
> >
> > On Thu, Feb 15, 2018 at 10:06 AM, Per olof Ljungmark <peo@nethead.se
> > <mailto:peo@nethead.se>> wrote:
> >
> >     On 02/15/18 08:56, Michael Schuster wrote:
> >     > Hi Per,
> >     >
> >     > On Thu, Feb 15, 2018 at 8:41 AM, Per olof Ljungmark <
> peo@nethead.se <mailto:peo@nethead.se>
> >     > <mailto:peo@nethead.se <mailto:peo@nethead.se>>> wrote:
> >     >
> >     >     Hi,
> >     >
> >     >     A process "squatter" from Cyrus-IMAP version 2.5.11 exits with
> signal
> >     >     11. The purpose of the process is to create an index of the
> content in a
> >     >     mailbox.
> >     >
> >     >     On large mailboxes, squatter coredumps, the final message from
> truss
> >     >     reads:
> >     >
> >     >     mmap(0x0,700448768,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0)
> =
> >     >     34783363072 (0x819400000)
> >     >     mmap(0x0,936334732,PROT_READ,MAP_SHARED,107,0x0) = 35483811840
> >     >     (0x843000000)
> >     >     SIGNAL 11 (SIGSEGV)
> >     >     process killed, signal = 11 (core dumped)
> >     >
> >     >
> >     > to me this looks like the error is happening *after* mmap()
> returned
> >     > successfully - most likely because "someone" miscalculates some
> pointer
> >     > and tries to access an unmapped address. Maybe (but that's
> conjecture),
> >     > PROT_READ is wrong here and someone is attempting to write to that
> >     > mapped region; I'm not 100% sure though whether that'd actually
> trigger
> >     > SIGSEGV.
> >     >
> >     > I'd suggest you do something like
> >     > $ gdb squatter core
> >     > (gdb) bt
> >     >
> >     > and look at the output, and maybe go to the maintainers of
> Cyrus-IMAP...
> >
> >     Hi,
> >
> >     gdb says,
> >
> >     (gdb) bt
> >     #0  0x00000000004049cc in ?? ()
> >     #1  0x0000000803456da4 in ?? ()
> >     #2  0x0000000804445130 in ?? ()
> >     #3  0x003875e5ffffcb00 in ?? ()
> >     #4  0x00000008047e7008 in ?? ()
> >     #5  0x00000008047e7048 in ?? ()
> >     #6  0x00000001040000c0 in ?? ()
> >     #7  0x0000000810800000 in ?? ()
> >     #8  0x0000000200000045 in ?? ()
> >     #9  0x000000083a400000 in ?? ()
> >     #10 0x00000008047e8e98 in ?? ()
> >     #11 0x00000000000003bb in ?? ()
> >     #12 0x00000008047e8eb8 in ?? ()
> >     #13 0x00000000000000bf in ?? ()
> >     #14 0x0ffd2a151071e550 in ?? ()
> >     #15 0x000000bf00000002 in ?? ()
> >     #16 0x37cf558c1298d1e7 in ?? ()
> >     #17 0x0135682800000000 in ?? ()
> >     #18 0x02e00a0e020d0336 in ?? ()
> >     #19 0x0487888c03b90d10 in ?? ()
> >     #20 0x062618da0556e126 in ?? ()
> >     #21 0x0000000006f31067 in ?? ()
> >     #22 0x0000000000000000 in ?? ()
> >
> >
> >
> >
> > --
> > Michael Schuster
> > http://recursiveramblings.wordpress.com/
> > recursion, n: see 'recursion'
>
> --
> Per olof Ljungmark
> +46 707 50 20 46
> Nethead AB
> Registered in Stockholm, Sweden
> SE556815226701
>



-- 
Michael Schuster
http://recursiveramblings.wordpress.com/
recursion, n: see 'recursion'



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