Does modern UBI/UBIFS still suffer from the 'unstable bits issue'?

[Richard Weinberger]

Tim,

Am Donnerstag, 1. März 2018, 17:15:44 CET schrieb Tim Harvey:
> Greetings,
> 
> I have a user with an IMX6 and raw NAND using UBI/UBIFS who has been
> able to reproduce a NAND corruption:

What does your user to reproduce this?

> [   10.611972] UBIFS (ubi0:2): background thread "ubifs_bgt0_2" started, PID
> 631 [   10.634365] ubi0 warning: ubi_io_read: error -74 (ECC error) while
> reading 253952 bytes from PEB 2807:8192, read only 253952 bytes, retry [  
> 10.657492] ubi0 warning: ubi_io_read: error -74 (ECC error) while reading
> 253952 bytes from PEB 2807:8192, read only 253952 bytes, retry [  
> 10.681137] ubi0 warning: ubi_io_read: error -74 (ECC error) while reading
> 253952 bytes from PEB 2807:8192, read only 253952 bytes, retry [  
> 10.704267] ubi0 error: ubi_io_read: error -74 (ECC error) while reading
> 253952 bytes from PEB 2807:8192, read 253952 bytes
> 
> The kernel they are using is a bit out of date but does have
> 'gpmi-nand: Handle ECC Errors in erased pages' [1] patch
> 
> I'm wondering if the 'unstable bits issue' [2] is still an issue or if
> the UBI/UBFS Documentation is out of date and this has been resolved.
> If it has been resolved, can anyone point me to the patches.

This issue is highly theoretical and I never actually saw it in the wild. 
Every single time someone claimed to suffer from that, it turned out to be 
something else. Currently UBI/UBIFS has no counter measurement, for the said 
reasons.
This reminds me that we have to update the website...

So did you verify (with your NAND vendor) that this really is the named issue?

Thanks,
//richard