On Wed, 29 Nov 2023, Joe Thornber wrote:
> On Wed, Nov 29, 2023 at 8:24 AM Joe Thornber <[email protected]> wrote:
>       Hi Eric,
>
> Since integrity is below thin I would say this is likely a real issue 
> with your hardware; probably causing thinp to head down the rarely used 
> error path.

While I suppose this is possible, the problem presented itself on two 
completely different NVMe mirror pairs, two NVMes of which are brand new. 
The system survived a 24 hour memory test and we have not seen any machine 
check exceptions or ECC errors, so is far as I can tell the hardware is 
working as expected.

> It looks like something is holding the rw_semaphore that protects 
> accesses to the thin_metadata. This could either be a process that is 
> blocked holding it (in which case you should be able to see it).  Or a 
> rarely used error path has omitted to release it.

Is any kernel tooling around finding what is holding the lock, or some 
kind of tracing mechanism that I could trigger while rw_semaphore is 
locked?

--
Eric Wheeler



> 
> 
> Looking at the code I think it's really unlikely that we've accidentally left 
> it unlocked.  So could you check
> all processes to see if any are holding it please, and check
> the kernel logs to see if any processes were killed for some reason.
> 
> - Joe
> 
> 
> 

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