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Date:      Mon, 26 Oct 2009 09:09:06 -0500
From:      Jaime Bozza <jbozza@mindsites.com>
To:        Kostik Belousov <kostikbel@gmail.com>, Dylan Cochran <heliocentric@gmail.com>
Cc:        "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org>
Subject:   RE: Possible scheduler (SCHED_ULE) bug?
Message-ID:  <CF092998EA82AE4D83AF9C9ECA9A8BDE02EB411A95@ATLAS.msg.local>
In-Reply-To: <20091023212104.GH2160@deviant.kiev.zoral.com.ua>
References:  <CF092998EA82AE4D83AF9C9ECA9A8BDE02EB411A85@ATLAS.msg.local> <bdf82f800910231328tfa4decfncd70ae0daad2bef6@mail.gmail.com> <20091023212104.GH2160@deviant.kiev.zoral.com.ua>

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From: Kostik Belousov [mailto:kostikbel@gmail.com]
> Can you look up the source line for kern_sendfile+0x90d in your
> kernel ? Do kgdb kernel.debug, then execute "list *(kern_sendfile+0x90d)"=
.

In my case, it was kern_sendfile+0x6ad (rebuilt with RELENG_7 this weekend)=
.

Here's the output:

(kgdb) list *(kern_sendfile+0x6ad)
0xc0855fdd is in kern_sendfile (atomic.h:160).
155     static __inline int
156     atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
157     {
158             u_char res;
159
160             __asm __volatile(
161             "       " MPLOCKED "            "
162             "       cmpxchgl %2,%1 ;        "
163             "       sete    %0 ;            "
164             "1:                             "

Not much to go on there.  I posted a backtrace in a previous email, but the=
 relevant sections (I think) are:

#14 0xc0855fdd in kern_sendfile (td=3D0xc771db40, uap=3D0xc72e2cfc, hdr_uio=
=3D0x0, trl_uio=3D0x0, compat=3D0) at atomic.h:160
#15 0xc0856d31 in do_sendfile (td=3D0xc771db40, uap=3D0xc72e2cfc, compat=3D=
0) at /usr/src/sys/kern/uipc_syscalls.c:1775
#16 0xc0856dd3 in sendfile (td=3D0xc771db40, uap=3D0xc72e2cfc) at /usr/src/=
sys/kern/uipc_syscalls.c:1746
#17 0xc0b01365 in syscall (frame=3D0xc72e2d38) at /usr/src/sys/i386/i386/tr=
ap.c:1094
#18 0xc0ae5960 in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s=
:262
#19 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)

I'm still going to test the specific boundary, but if there's more informat=
ion I can give, let me know!

Jaime





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