Re: [2.6.25-rc5-mm1] BUG: spinlock bad magic early during boot

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From: Dave Hansen
Date: Friday, March 14, 2008 - 2:35 pm

On Fri, 2008-03-14 at 21:51 +0100, Eric Piel wrote:

I *can* probably do it earlier, maybe even statically, but I think
you're missing the point a bit here.  We've just been super lucky so far
that populate_rootfs() doesn't depend on any other initcalls (or at
least BUG_ON() because of them).  There may be some more buglets hiding
around.

It'd be a shame to have to have "super_early_fs_initcall()" logic for
every part of the VFS or any other initcall for that matter that you
might need.  How do we tell all future VFS hackers that they have to do
this so that the next guy doesn't break it?  I certainly missed it. :)

We could separate out the initcalls and just have the fs ones run before
the rest do.  But, I'm not sure what interactions *THAT* might have.
There are arch-specific initcalls, and I have no idea if the fs init
code depends on *those*.  That's a lot of code to check.

It is nailed when you the patch says:

+       /*
+        * Never do this at home, only the user-space is allowed to open a file.
+        * The clean way would be to use the firmware loader. But this code must be run
+        * before there is any userspace available. So we need a static/init firmware
+        * infrastructure, which doesn't exist yet...
+        */

I think requiring FS access this early in the boot processes is just
broken.  It seems like the author of the patch knew a better way and
tried to get away with a hack.  I think it backfired. :)

-- Dave

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Messages in current thread:
2.6.25-rc5-mm1, Andrew Morton, (Tue Mar 11, 1:14 am)
[Build Faliure] 2.6.25-rc5-mm1 build fails , Kamalesh Babulal, (Tue Mar 11, 3:16 am)
Re: [Build Faliure] 2.6.25-rc5-mm1 build fails, Edward Shishkin, (Tue Mar 11, 3:56 am)
Re: 2.6.25-rc5-mm1 (paravirt/vsmp/no PCI), Randy Dunlap, (Tue Mar 11, 10:09 am)
Re: 2.6.25-rc5-mm1 (paravirt/vsmp/no PCI), Jeremy Fitzhardinge, (Tue Mar 11, 11:18 am)
Re: [Build Failure] 2.6.25-rc5-mm1 Build fails with allmod ..., Bartlomiej Zolnierki ..., (Tue Mar 11, 12:35 pm)
Re: [Build Failure] 2.6.25-rc5-mm1 Build fails with allmod ..., Bartlomiej Zolnierki ..., (Tue Mar 11, 12:36 pm)
Re: 2.6.25-rc5-mm1, serge, (Tue Mar 11, 1:23 pm)
Re: 2.6.25-rc5-mm1, Andrew Morton, (Tue Mar 11, 1:39 pm)
Re: 2.6.25-rc5-mm1 (paravirt/vsmp/no PCI), Ravikiran G Thirumalai, (Tue Mar 11, 5:10 pm)
Re: 2.6.25-rc5-mm1, Dave Young, (Tue Mar 11, 6:14 pm)
Re: 2.6.25-rc5-mm1 (paravirt/vsmp/no PCI), Randy Dunlap, (Tue Mar 11, 6:42 pm)
Re: 2.6.25-rc5-mm1 (paravirt/vsmp/no PCI), Jeremy Fitzhardinge, (Tue Mar 11, 6:51 pm)
Re: 2.6.25-rc5-mm1 (paravirt/vsmp/no PCI), Ingo Molnar, (Wed Mar 12, 12:14 am)
Re: 2.6.25-rc5-mm1 - x86_64 boot problem ?, Badari Pulavarty, (Wed Mar 12, 11:10 am)
Re: 2.6.25-rc5-mm1 - x86_64 boot problem ?, Andrew Morton, (Wed Mar 12, 11:15 am)
Re: 2.6.25-rc5-mm1, Torsten Kaiser, (Wed Mar 12, 12:33 pm)
Re: 2.6.25-rc5-mm1, Andrew Morton, (Wed Mar 12, 12:44 pm)
Re: 2.6.25-rc5-mm1, Torsten Kaiser, (Wed Mar 12, 1:01 pm)
Re: [BUG] 2.6.25-rc5-mm1 kernel panic with "Exception: 501 ..., Benjamin Herrenschmidt, (Wed Mar 12, 1:40 pm)
[2.6.25-rc5-mm1] BUG: spinlock bad magic early during boot, Tilman Schmidt, (Wed Mar 12, 4:54 pm)
[2.6.25-rc5-mm1] WARNING: at drivers/base/sys.c:173, Tilman Schmidt, (Wed Mar 12, 5:15 pm)
Re: 2.6.25-rc5-mm1 shutdown crash, Helge Hafting, (Thu Mar 13, 7:03 am)
Re: 2.6.25-rc5-mm1 shutdown crash, Andrew Morton, (Thu Mar 13, 9:12 am)
Re: 2.6.25-rc5-mm1 - x86_64 boot problem with git-sched.patch, Badari Pulavarty, (Thu Mar 13, 10:09 am)
Re: 2.6.25-rc5-mm1 - x86_64 boot problem with git-sched.patch, Badari Pulavarty, (Thu Mar 13, 10:40 am)
Re: 2.6.25-rc5-mm1 - x86_64 boot problem with git-sched.patch, Guillaume Chazarain, (Thu Mar 13, 10:55 am)
Re: 2.6.25-rc5-mm1 - x86_64 boot problem with git-sched.patch, Badari Pulavarty, (Thu Mar 13, 11:20 am)
Re: 2.6.25-rc5-mm1, Torsten Kaiser, (Thu Mar 13, 3:05 pm)
Re: 2.6.25-rc5-mm1: "consolechars" hangs on boot, Laurent Riffard, (Thu Mar 13, 3:07 pm)
Re: 2.6.25-rc5-mm1, Andrew Morton, (Thu Mar 13, 3:35 pm)
Re: 2.6.25-rc5-mm1, Badari Pulavarty, (Thu Mar 13, 4:10 pm)
Re: [2.6.25-rc5-mm1] WARNING: at drivers/base/sys.c:173, Tilman Schmidt, (Thu Mar 13, 5:01 pm)
Re: 2.6.25-rc5-mm1: "consolechars" hangs on boot, Oleg Nesterov, (Thu Mar 13, 10:26 pm)
Re: [2.6.25-rc5-mm1] WARNING: at drivers/base/sys.c:173, Tilman Schmidt, (Fri Mar 14, 2:58 am)
Re: 2.6.25-rc5-mm1: "consolechars" hangs on boot, Laurent Riffard, (Fri Mar 14, 2:06 pm)
Re: [2.6.25-rc5-mm1] BUG: spinlock bad magic early during boot, Dave Hansen, (Fri Mar 14, 2:35 pm)
Re: [2.6.25-rc5-mm1] WARNING: at drivers/base/sys.c:173, Tilman Schmidt, (Sat Mar 15, 5:16 am)
Re: 2.6.25-rc5-mm1 build failure of pcsp.c, Mariusz Kozlowski, (Sun Mar 16, 2:38 pm)
Re: [2.6.25-rc5-mm1] regression: cannot run Postfix sendma ..., Rafael J. Wysocki, (Thu Mar 20, 3:21 am)
Re: [2.6.25-rc5-mm1] regression: cannot run Postfix sendma ..., Rafael J. Wysocki, (Thu Mar 20, 7:38 am)
Re: 2.6.25-rc5-mm1, Ingo Molnar, (Fri Mar 21, 5:12 am)
Re: 2.6.25-rc5-mm1 shutdown crash, Helge Hafting, (Tue Mar 25, 5:23 am)
Re: 2.6.25-rc5-mm1 sparc64 boot problems due to generic pc ..., Mariusz Kozlowski, (Fri Mar 28, 3:52 pm)
Re: 2.6.25-rc5-mm1 sparc64 boot problems due to generic pc ..., Benjamin Herrenschmidt, (Fri Mar 28, 5:44 pm)