Re: 2.5.44: How to decode call trace

Re: 2.5.44: How to decode call trace

[Andi Kleen]

Olaf Dietsche <olaf.dietsche#list.linux-kernel@t-online.de> writes:
> and this is the code:
> static int __fscap_lookup(struct vfsmount *mnt, struct nameidata *nd)
> {
> 	static char name[] = ".capabilities";
> 	nd->mnt = mntget(mnt);
> 	nd->dentry = dget(mnt->mnt_sb->s_root);
> 	nd->flags = 0;
> 	return path_walk(name, nd);
> }
> 
> What does .text.lock.namei and name.810 mean?

.text.lock.namei means that it hung in the slow path of a spinlock that
is referenced from namei.c

name.810 is a static data variable, probably the static char name[]
shown above. Remember the kernel backtrace is not exact and can print
random stack junk that looks like return addresses too. You always have 
to sanity check each entry.

> Is there a way to get the line number out of these hex values?

addr2line -e vmlinux ... does this when you compile the kernel with -g 

-Andi

Re: 2.5.44: How to decode call trace

[bert hubert]

On Wed, Oct 23, 2002 at 05:50:41AM +0200, Andi Kleen wrote:

> > Is there a way to get the line number out of these hex values?
> 
> addr2line -e vmlinux ... does this when you compile the kernel with -g 

Also interesting is http://ds9a.nl/symoops

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Re: 2.5.44: How to decode call trace

[Olaf Dietsche]

bert hubert <ahu@ds9a.nl> writes:

> On Wed, Oct 23, 2002 at 05:50:41AM +0200, Andi Kleen wrote:
>
>> > Is there a way to get the line number out of these hex values?
>> 
>> addr2line -e vmlinux ... does this when you compile the kernel with -g 
>
> Also interesting is http://ds9a.nl/symoops

This is a real shortcut. Thanks.

Regards, Olaf.

Re: 2.5.44: How to decode call trace

[Olaf Dietsche]

Andi Kleen <ak@suse.de> writes:

> Olaf Dietsche <olaf.dietsche#list.linux-kernel@t-online.de> writes:
>> and this is the code:
>> static int __fscap_lookup(struct vfsmount *mnt, struct nameidata *nd)
>> {
>> 	static char name[] = ".capabilities";
>> 	nd->mnt = mntget(mnt);
>> 	nd->dentry = dget(mnt->mnt_sb->s_root);
>> 	nd->flags = 0;
>> 	return path_walk(name, nd);
>> }
>> 
>> What does .text.lock.namei and name.810 mean?
>
> .text.lock.namei means that it hung in the slow path of a spinlock that
> is referenced from namei.c

I guess this is what __down_failed means.

> name.810 is a static data variable, probably the static char name[]
> shown above. Remember the kernel backtrace is not exact and can print
> random stack junk that looks like return addresses too. You always have 
> to sanity check each entry.

Ok, I'll keep that in mind.

>> Is there a way to get the line number out of these hex values?
>
> addr2line -e vmlinux ... does this when you compile the kernel with -g 

Great! This is what I was searching for.

When I build with "make -k EXTRA_CFLAGS=-g EXTRA_LDFLAGS=-g bzImage",
I get a ton of error messages from drivers/acpi/include/actypes.h and
other acpi related stuff, starting with: #error ACPI_MACHINE_WIDTH not
defined. Maybe this is not the usual way to build with -g, but I don't
get these errors with "make -k bzImage". Maybe someone is interested
in this.

Anyway, I come around this by first building with "EXTRA_CFLAGS=-g
EXTRA_LDFLAGS=-g", ignoring the error messages and then a second try
with only EXTRA_LDFLAGS=-g.

Regards, Olaf.

Re: [ACPI] Re: 2.5.44: How to decode call trace

[Matthew Wilcox]

On Wed, Oct 23, 2002 at 12:33:25PM +0200, Olaf Dietsche wrote:
> When I build with "make -k EXTRA_CFLAGS=-g EXTRA_LDFLAGS=-g bzImage",
> I get a ton of error messages from drivers/acpi/include/actypes.h and
> other acpi related stuff, starting with: #error ACPI_MACHINE_WIDTH not
> defined. Maybe this is not the usual way to build with -g, but I don't
> get these errors with "make -k bzImage". Maybe someone is interested
> in this.

Not really.  Users shouldn't be overriding EXTRA_CFLAGS, it's for the
benefit of various parts of the kernel.  Some other parts of the kernel
you break by doing this:

./arch/i386/mach-generic/Makefile:EXTRA_CFLAGS  += -I../kernel
./drivers/ide/pci/Makefile:EXTRA_CFLAGS := -Idrivers/ide
./drivers/message/fusion/Makefile:EXTRA_CFLAGS += ${MPT_CFLAGS}
./drivers/usb/storage/Makefile:EXTRA_CFLAGS     := -Idrivers/scsi
./fs/smbfs/Makefile:EXTRA_CFLAGS += -DSMBFS_PARANOIA
./fs/xfs/Makefile:EXTRA_CFLAGS +=        -Ifs/xfs -funsigned-char
./sound/oss/emu10k1/Makefile:    EXTRA_CFLAGS += -DEMU10K1_DEBUG

The normal way to do what you want is to edit the Makefile and add -g
directly to CFLAGS.

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Re: 2.5.44: How to decode call trace

[Olaf Dietsche]

Matthew Wilcox <willy@debian.org> writes:

> The normal way to do what you want is to edit the Makefile and add -g
> directly to CFLAGS.

Ok, thanks.

Regards, Olaf.

2.5.44: How to decode call trace

[Olaf Dietsche]

I have the following call tree:

Oct 22 22:35:36 goat kernel: rm            D 00000246     0   615    387                     (NOTLB)
Oct 22 22:35:36 goat kernel: Call Trace:
Oct 22 22:35:36 goat kernel:  [<c0105ebf>] __down+0x67/0xb8
Oct 22 22:35:36 goat kernel:  [<c0112a5c>] default_wake_function+0x0/0x34
Oct 22 22:35:36 goat kernel:  [<c0106034>] __down_failed+0x8/0xc
Oct 22 22:35:36 goat kernel:  [<c0143601>] .text.lock.namei+0x5/0x174
Oct 22 22:35:36 goat kernel:  [<c0140768>] do_lookup+0x9c/0x1bc
Oct 22 22:35:36 goat kernel:  [<c0140dde>] link_path_walk+0x556/0x868
Oct 22 22:35:36 goat kernel:  [<c015bedc>] ext2_commit_chunk+0x38/0x6c
Oct 22 22:35:36 goat kernel:  [<e08696a9>] name.810+0xd/0x10 [fscaps]
Oct 22 22:35:36 goat kernel:  [<c015bf09>] ext2_commit_chunk+0x65/0x6c
Oct 22 22:35:36 goat kernel:  [<e086969c>] name.810+0x0/0x10 [fscaps]
Oct 22 22:35:36 goat kernel:  [<c0141117>] path_walk+0x27/0x28
Oct 22 22:35:36 goat kernel:  [<e086909f>] __fscap_lookup+0x3f/0x40 [fscaps]
Oct 22 22:35:36 goat kernel:  [<e0869266>] fscap_drop_op+0x1a/0x5c [fscaps]
Oct 22 22:35:36 goat kernel:  [<c01424de>] vfs_unlink+0x14e/0x178
Oct 22 22:35:36 goat kernel:  [<c01425b2>] sys_unlink+0xaa/0x120
Oct 22 22:35:36 goat kernel:  [<c0106d93>] syscall_call+0x7/0xb

and this is the code:
static int __fscap_lookup(struct vfsmount *mnt, struct nameidata *nd)
{
	static char name[] = ".capabilities";
	nd->mnt = mntget(mnt);
	nd->dentry = dget(mnt->mnt_sb->s_root);
	nd->flags = 0;
	return path_walk(name, nd);
}

What does .text.lock.namei and name.810 mean?
Is there a way to get the line number out of these hex values?

TIA
Regards, Olaf.