Message-Id: <E1JSF5r-0007vI-1v@pomaz-ex.szeredi.hu>
Date:	Thu, 21 Feb 2008 18:20:23 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	roland@...hat.com
CC:	jdike@...toit.com, miklos@...redi.hu, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [bug] uml doesn't boot under 2.6.25-rc1 host (was Re: 2.6.24-mm1 bugs)

> > > >  - UML doesn't boot: guest is 2.6.24-mm1 also, haven't tried any
> > > >    other.  Same guest boots fine on 2.6.24 host.
> > > 
> > > What does it do?
> > 
> > See below.
> 
> This bug seems to have made it to mainline as well, starting with
> -rc1.  Any ideas?  Should I start bisecting?

Bisected it down to

good e7b5e11eaaa8ef93a34e68016de51152d0d62911
bad  bde6f5f59c2b2b48a7a849c129d5b48838fe77ee

I strongly suspect it's one of the ptrace cleanup patches.  Roland,
could you please have a look?

I'm running 32bit UML on 64bit host, this may have to do with
triggering this, otherwise perhaps more people would have complained.

Thanks,
Miklos

> > GNU gdb 6.6.50.20070726-cvs
> > Copyright (C) 2007 Free Software Foundation, Inc.
> > GDB is free software, covered by the GNU General Public License, and you are
> > welcome to change it and/or distribute copies of it under certain conditions.
> > Type "show copying" to see the conditions.
> > There is absolutely no warranty for GDB.  Type "show warranty" for details.
> > This GDB was configured as "x86_64-suse-linux"...
> > Using host libthread_db library "/lib64/libthread_db.so.1".
> > (gdb) r umid=uml
> > Starting program: /store/quilt/linux/linux umid=uml
> > Core dump limits :
> >         soft - 0
> >         hard - NONE
> > Checking that ptrace can change system call numbers...OK
> > Checking syscall emulation patch for ptrace...missing
> > Checking for tmpfs mount on /dev/shm...nothing mounted on /dev/shm
> > Checking PROT_EXEC mmap in /tmp/...OK
> > Checking for the skas3 patch in the host:
> >   - /proc/mm...not found: No such file or directory
> >   - PTRACE_FAULTINFO...not found: Invalid argument
> >   - PTRACE_LDT...not found: Invalid argument
> > UML running in SKAS0 mode
> > Adding 24977408 bytes to physical memory to account for exec-shield gap
> > [    0.000000] Linux version 2.6.24-mm1 (mszeredi@...sk) (gcc version 4.2.1 (SUSE Linux)) #26 Fri Feb 15 11:05:54 CET 2008
> > [    0.010000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 14179
> > [    0.010000] Kernel command line: root=98:0
> > [    0.010000] PID hash table entries: 256 (order: 8, 1024 bytes)
> > [    0.010000] Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
> > [    0.010000] Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
> > [    0.010000] Memory: 29504k available
> > [    0.270000] Mount-cache hash table entries: 512
> > [    0.270000] Checking for host processor cmov support...Yes
> > [    0.270000] Checking that host ptys support output SIGIO...Yes
> > [    0.270000] Checking that host ptys support SIGIO on close...No, enabling workaround
> > [    0.270000] net_namespace: 184 bytes
> > [    0.270000] Using 2.6 host AIO
> > [    0.270000] NET: Registered protocol family 16
> > [    0.300000] NET: Registered protocol family 2
> > [    0.310000] Time: itimer clocksource has been installed.
> > [    0.390000] IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
> > [    0.390000] TCP established hash table entries: 2048 (order: 2, 16384 bytes)
> > [    0.390000] TCP bind hash table entries: 2048 (order: 3, 40960 bytes)
> > [    0.390000] TCP: Hash tables configured (established 2048 bind 2048)
> > [    0.390000] TCP reno registered
> > [    0.420000] Checking host MADV_REMOVE support...<3>MADV_REMOVE failed, err = -38
> > [    0.420000] Can't release memory to the host - memory hotplug won't be supported
> > [    0.420000] mconsole (version 2) initialized on /home/mszeredi/.uml/uml/mconsole
> > [    0.420000] Host TLS support detected
> > [    0.420000] Detected host type: x86_64 (GDT indexes 12 to 15)
> > [    0.420000] fuse init (API version 7.9)
> > [    0.420000] io scheduler noop registered (default)
> > [    0.420000] loop: module loaded
> > [    0.420000] TCP cubic registered
> > [    0.420000] NET: Registered protocol family 1
> > [    0.420000] Initialized stdio console driver
> > [    0.420000] Console initialized on /dev/tty0
> > [    0.420000] console [tty0] enabled
> > [    0.420000] console [mc-1] enabled
> > [    0.420000]  ubda: unknown partition table
> > [    0.420000] kjournald starting.  Commit interval 5 seconds
> > [    0.420000] EXT3-fs: mounted filesystem with ordered data mode.
> > [    0.420000] VFS: Mounted root (ext3 filesystem) readonly.
> > [    0.420000] Failed to get registers from stub, errno = 3
> > [    0.420000] wait_stub_done : failed to wait for SIGTRAP, pid = 30073, n = 30073, errno = 0, status = 0x0
> > [New LWP 30070]
> >                [New LWP 30071]
> >                               [New LWP 30072]
> > 
> > Program received signal SIGTERM, Terminated.
> > 0xffffe430 in __kernel_vsyscall ()
> > (gdb) bt
> > #0  0xffffe430 in __kernel_vsyscall ()
> > #1  0xf7eabc26 in kill () from /lib/libc.so.6
> > #2  0x0806cf82 in os_dump_core () at arch/um/os-Linux/util.c:105
> > #3  0x0805d64d in fatal_sigsegv () at arch/um/kernel/trap.c:141
> > #4  0x0806e32b in wait_stub_done (pid=30073)
> >     at arch/um/os-Linux/skas/process.c:94
> > #5  0x0806d94b in run_syscall_stub (mm_idp=0xb26ff18, syscall=123,
> >     args=0xb067e08, expected=0, addr=0xb067ea4, done=1)
> >     at arch/um/os-Linux/skas/mem.c:86
> > #6  0x0806f997 in write_ldt_entry (mm_idp=0xb26ff18, func=1, desc=0xb067e94,
> >     addr=0xb067ea4, done=1) at arch/um/sys-i386/ldt.c:72
> > #7  0x08070434 in init_new_ldt (new_mm=0xb26ff18, from_mm=0x0)
> >     at arch/um/sys-i386/ldt.c:425
> > #8  0x0805de43 in init_new_context (task=0xb05bc00, mm=0xb26fdc0)
> >     at arch/um/kernel/skas/mmu.c:87
> > #9  0x080ce3c1 in bprm_mm_init (bprm=0xb1a6980) at fs/exec.c:337
> > #10 0x080cfa2d in do_execve (filename=0x820d61f "/sbin/init", argv=0x8250020,
> >     envp=0x8250240, regs=0xb05be04) at fs/exec.c:1296
> > #11 0x080599e8 in execve1 (file=0x820d61f "/sbin/init", argv=0x8250020,
> >     env=0x8250240) at arch/um/kernel/exec.c:62
> > #12 0x08059a4f in um_execve (file=0x820d61f "/sbin/init", argv=0x8250020,
> >     env=0x8250240) at arch/um/kernel/exec.c:78
> > #13 0x0805c4fb in kernel_execve (filename=0x820d61f "/sbin/init",
> > ---Type <return> to continue, or q <return> to quit---
> >     argv=0x8250020, envp=0x8250240) at arch/um/kernel/syscall.c:146
> > #14 0x08059616 in run_init_process (init_filename=0x820d61f "/sbin/init")
> >     at init/main.c:763
> > #15 0x080596d3 in init_post () at init/main.c:809
> > #16 0x08049a74 in kernel_init (unused=0x0) at init/main.c:865
> > #17 0x0806ac31 in run_kernel_thread (fn=0x8049a00 <kernel_init>, arg=0x0,
> >     jmp_ptr=0xb05be70) at arch/um/os-Linux/process.c:267
> > #18 0x0805ad62 in new_thread_handler () at arch/um/kernel/process.c:153
> > #19 0x00000000 in ?? ()
> > (gdb)
> > 
> 
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