Kernel – BAFM

Rescuing a rebooting machine that’s hanging

May 24, 2008June 21, 2013 Christian Leave a comment

One of my co-worker approached me today with a weird problem. Yesterday he had a disk in a 900GiB array failing which he replaced. After that, he run a rebuild/verification, fsck’ed the file system and tried to mount the volume again.

Apparently the mount produced a kernel oops (guess what, the 900GiB is running reiserfs), thus leaving the kernel tainted (or what do they call it ?). So he tried to reboot the box but it didn’t reboot. It started rebooting but then hung (as in not continuing the reboot). He tried to ssh back to the box, and it worked just fine.

This is where sysrq comes in handy.

# This is gonna activate the sysrq
echo 1 &gt; /proc/sys/kernel/sysrq

# Now, since we ain&#039;t at a console, we can&#039;t use the sysrq keys
# (&quot;b&quot; for reboot, &quot;o&quot; for shutdown)
echo b &gt; /proc/sysrq-trigger

# This is gonna activate the sysrq

echo 1 > /proc/sys/kernel/sysrq

# Now, since we ain't at a console, we can't use the sysrq keys

# ("b" for reboot, "o" for shutdown)

echo b > /proc/sysrq-trigger

That’ll restart the box, and cha-ching .. 😀

git-lkml for stupid people (like me)

August 16, 2007August 16, 2007 Christian Leave a comment

OK, as Stephen recently asked why there is a double inclusion of in kernel/sysctl.c (and I asked Greg and Randy); I finally decided to write a patch to the LKML for possible inclusion.

But, git ain’t easy for people like me (who are used to the easiness of say – subversion or even cvs). So here’s what I did (thanks to Fernando for the help earlier today):

$ vim kernel/sysctl.c
// change something
$ git checkout -b sysctl
// create a new branch from your changes, based upon the master repository
$ git commit -a -s
// commit the changes to your newly created branch
$ git format-patch master..sysctl
// Enter a subject and then a separate description
// and you should have a new file in the current working directory starting like 0001-*.patch

$ vim kernel/sysctl.c

// change something

$ git checkout -b sysctl

// create a new branch from your changes, based upon the master repository

$ git commit -a -s

// commit the changes to your newly created branch

$ git format-patch master..sysctl

// Enter a subject and then a separate description

// and you should have a new file in the current working directory starting like 0001-*.patch

Now you should have a mailable patch, ready to be sent upstream that looks like this:

From 839ce261cf688d62bebd9ae3a0101dd672018940 Mon Sep 17 00:00:00 2001
From: Christian Heim 
Date: Sun, 19 Aug 2007 12:51:52 +0200
Subject: [PATCH] Remove double inclusion of linux/capability.h

Remove the second inclusion of linux/capability.h, which has been introduced
with "[PATCH] move capable() to capability.h" (or commit c59ede7b78db329949d9cdcd7064e22d357560ef).

Signed-off-by: Christian Heim 
---
 kernel/sysctl.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8bdb8c0..9029690 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -27,7 +27,6 @@
 #include 
 #include 
 #include 
-#include 
 #include 
 #include 
 #include 

--
1.5.3.rc4

From 839ce261cf688d62bebd9ae3a0101dd672018940 Mon Sep 17 00:00:00 2001

From: Christian Heim

Date: Sun, 19 Aug 2007 12:51:52 +0200

Subject: [PATCH] Remove double inclusion of linux/capability.h

Remove the second inclusion of linux/capability.h, which has been introduced

with "[PATCH] move capable() to capability.h" (or commit c59ede7b78db329949d9cdcd7064e22d357560ef).

Signed-off-by: Christian Heim

---

kernel/sysctl.c | 1 -

1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c

index 8bdb8c0..9029690 100644

--- a/kernel/sysctl.c

+++ b/kernel/sysctl.c

@@ -27,7 +27,6 @@

#include

-#include

#include

1.5.3.rc4

And if you wanna delete the branch afterwards again, just do this:

$ git checkout master
// Switch back to the master branch
$ git branch -D sysctl
// Delete the old branch named "sysctl"

$ git checkout master

// Switch back to the master branch

$ git branch -D sysctl

// Delete the old branch named "sysctl"

hardened-sources-2.6.18

November 11, 2006November 11, 2006 Christian Leave a comment

Today (OK, it’s yesterday now, it’s again after 12:00) I had a little fun with pappy (Alexander Gabert) preparing 2.6.18 for prime time 😀

$ ls -AGg 2.6.18
-rw-r--r-- 1   1593 Jan 25 23:25 1500_cvs-2007-1000.patch
-rw-r--r-- 1    797 Jan 25 23:25 4000_deprecate-sk98lin.patch
-rw-r--r-- 1  32192 Jan 25 23:25 4105_dm-bbr.patch
-rw-r--r-- 1 125781 Jan 25 23:25 4300_squashfs-3.1.patch
-rw-r--r-- 1   5710 Jan 25 23:25 4405_alpha-sysctl-uac.patch
-rw-r--r-- 1 864955 Jan 25 23:25 4450_grsec-2.1.9-2.6.18.6-200611100917.patch
-rw-r--r-- 1    910 Jan 25 23:25 4451_grsec-2.1.9-2.6.18.2-mute-warnings.patch
-rw-r--r-- 1   1034 Jan 25 23:25 4452_selinux-avc_audit-log-curr_ip-grsec.patch
-rw-r--r-- 1   2097 Jan 25 23:25 4453_pax_curr_ip-fixes.patch

$ ls -AGg 2.6.18

-rw-r--r-- 1 1593 Jan 25 23:25 1500_cvs-2007-1000.patch

-rw-r--r-- 1 797 Jan 25 23:25 4000_deprecate-sk98lin.patch

-rw-r--r-- 1 32192 Jan 25 23:25 4105_dm-bbr.patch

-rw-r--r-- 1 125781 Jan 25 23:25 4300_squashfs-3.1.patch

-rw-r--r-- 1 5710 Jan 25 23:25 4405_alpha-sysctl-uac.patch

-rw-r--r-- 1 864955 Jan 25 23:25 4450_grsec-2.1.9-2.6.18.6-200611100917.patch

-rw-r--r-- 1 910 Jan 25 23:25 4451_grsec-2.1.9-2.6.18.2-mute-warnings.patch

-rw-r--r-- 1 1034 Jan 25 23:25 4452_selinux-avc_audit-log-curr_ip-grsec.patch

-rw-r--r-- 1 2097 Jan 25 23:25 4453_pax_curr_ip-fixes.patch

So far all patches are applying fine and according to Alexander it even works on his workstation. But I’ll wait for Steve/Ned to get back to me telling me if this release works for them or not (as they had serious issues with their hardened desktops – something about the cursor being stuck in the corners).

You may also ask, what for is this mute-warning patch. Basically the new grsecurity patch increased the kernel’s verbosity while running make about two times 😮 . Thus we decided to revert the warnings to the ones used in vanilla (that’s via CFLAGS).

F*cking summer

July 30, 2006August 16, 2014 Christian Leave a comment

Oh, yeah baby *g*. It’s finally hot f*cking summer and I *really* like it. We have now three weeks in a row sunny weather with no rain at all.

Everyone running around with less or nearly no clothes (heh, especially the girls) is also a nice present from above.

Personally I haven’t felt better the last two years. Maybe that’s depending on my previous depressions and the like (you know these thoughts .. ) but this summer is definitely going rock my life!

christel, babe 😛 I have to say you’re not alone with those mood swings. I have them also from time to time. Everyone (well my friends :P) is bitching at me then like “C’mon, don’t be so negative about … blah” or “Why are you so angry at … blah ?”.

You’re also right, piling the anger up isn’t such a good thing (TM). Stress from work (or family :() is also doing its part.

Aaah, Joshua; I nearly forgot about you! Take of that hat! It makes you look like a clown, which you really are not 🙂 And I’m gonna blog about my 15 billion pieces puzzle tomorrow (uploading ~180M of jpeg’s isn’t that fast with stupid 16k upstream).

Oh, by the way thanks Sven for the really great introduction of frilled! I really would like to see more of those (even if it will get pretty hard by the time :))

But enough of the bitching, now some infos/updates on the Gentoo/FOSS-related things.

Herbert announced another release candidate for linux-vserver (surprise 😛 rc27), and I really hope we’ll see the final version within this month (haha since this month ends tomorrow, nah the next month). I’ll prepare a patch-tarball and an ebuild later.
As I earlier mentioned, I took some of Henrik’s packages (while he was on his Hiatus). And now he announced his resignation!. *sigh*. Henrik, I really hate to see you go.
I also joined the kernel-monkey herd (thanks Henrik, Daniel and John for letting me), did my first release for genpatches (and messed it up, I *know*), became devoted to the mobile-herd (thanks Stefan for asking) and also poked around a bit with the hardened patchset for 2.6.17 (ah, thanks again John :)).