[dm-crypt] The weird bug again: semid XXXXXX: semop failed for cookie 0xdeadbeef: incorrect semaphore state

Milan Broz mbroz at redhat.com
Wed Aug 17 09:31:45 CEST 2011


On 08/16/2011 11:55 PM, Thomas Bächler wrote:
> Am 16.08.2011 23:44, schrieb Milan Broz:
>> On 08/16/2011 10:45 PM, Thomas Bächler wrote:
>>> I am getting reports of this error again:
>>>
>>> semid 491524: semop failed for cookie 0xd4dc159: incorrect semaphore state
>>> Failed to set a proper state for notification semaphore identified by
>>> cookie value 223199577 (0xd4dc159) to initialize waiting for incoming
>>> notifications.
>>>
>>> This issue is so weird that I don't know where to start. Apparently,
>>> this problem appears whenever chromium is running, and disappears when
>>> you quit chromium. I'm confused about this. Very confused.
>>
>> I know that this bug is still there. I think that the problem is:
>>
>> - kernel, in response to devmapper library request, send uevent with cookie
>> - kernel reports failure (despite uevent was sent), I guess it is
>> some memory allocation error later
>> - libdevmapper takes error path, destroying semaphore, which was already
>> destroyed in udev rules
>>
>> So my guess is that connection with chromium just it perhaps allocates most
>> of system memory and some allocation in kernel perhaps fail then.
> 
> Then this would probably be reproducible with other programs, too. So
> far, the connection has been only made with chromium. I would love to
> find another test case though.

Well, this is the most strange report so far. If more people can reproduce it,
there must be a connection. Isn't chromium using system semaphores intensively?
(I have no idea.)

What says "ipcs -s" (with and without chromium running)?

Will increasing number of system semaphores help (first number)?
sysctl -a |grep sem

Can you try to increase it to 1000 for example
sysctl -w kernel.sem=1000


> 
>> The final state should be correct, so you can (I hope) ignore that error
>> for now.
> 
> Don't the LUKS commands abort after this error? (Don't remember).

It should not.

Milan



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