[FS#284] WRT1900acs, wifi stops workign under havy load

[LEDE Bugs]

The following task has a new comment added:

FS#284 - WRT1900acs, wifi stops workign under havy load
User who did this - Carlo (acarlo)

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Found out which is exactly the change that introduced the issue with the wifi.

d15dc7e85dbf38c07dd5a7f8068ee6655830548e is the first bad commit
commit d15dc7e85dbf38c07dd5a7f8068ee6655830548e
Author: John Crispin 
Date:   Mon Oct 31 16:38:26 2016 +0100

    fstools: update to latest git HEAD
    
    adds f2fs support
    
    Signed-off-by: John Crispin 

:040000 040000 d10d6f1edb2d916c88f844529897be401c0415af a654e081b6bea3460a4cd606c64dc3fd9b49d0af M	package


The issue can be triggered in my case doing these steps:

1) attach a USB 3.0 HDD formatted ext4
2) create a samba share pointing to a folder on the HDD
3) try to transfer a large file from the HDD to the smb client.

The transfer will die after few hundreds megabytes and the systemlog will show the aforementioned kernel error messages on the wifi.

All the tests have been done using the 5GHz network in ac.

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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=284#comment843