Re: 2.6.25-git2: BUG: unable to handle kernel paging request atffffffffffffffff

From: Linus Torvalds
Date: Tue Apr 22 2008 - 14:57:59 EST




On Tue, 22 Apr 2008, Zdenek Kabelac wrote:
>
> Unsure how it is related to my orginal Oops post - but now when I've
> debug pagealloc enabled this appeared in my log after resume - should
> I open new bug for this - or could this be part of the problem I've
> experienced later?
>
> (Note - now I'm running commit: 8a81f2738f10ca817c975cec893aa58497e873b2
>
> sd 0:0:0:0: [sda] Starting disk
> mmc0: new SD card at address 5a61
> mmc mmc0:5a61: parent mmc0 is sleeping, will not add
> ------------[ cut here ]------------
> WARNING: at drivers/base/power/main.c:78 device_pm_add+0x6c/0xf0()

This is unrelated to the other issue, I think.

Your warning comes from commit 58aca23226a19983571bd3b65167521fc64f5869,
which admittedly looks like total crap. Rafael, what's the point of that
commit?

I read the commit message, but I can't make myself agree with the commit
code itself. If it's a "checking that the order is correct" thing, it
should be a warning, but not change the actual _action_ of the code.

Because the commit refused to add the device, it is also then the direct
reason for the oops you get later, as far as I can tell:

> BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
> IP: [klist_del+29/128] klist_del+0x1d/0x80
> PGD 0
> Oops: 0000 [1] PREEMPT SMP DEBUG_PAGEALLOC
> CPU 0
> Call Trace:
> [bus_remove_device+158/208] bus_remove_device+0x9e/0xd0
> [device_add+1358/1376] device_add+0x54e/0x560

So I would suggest reverting that commit, or at least just making it a
warning (while still registering the device).

Linus
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