JFFS2 deadlock, kernel 3.4.11

[Thomas.Betker at rohde-schwarz.com]

Hello Joakim,

there was a minor error in my original post:

> The GC thread hangs in lock_page(page), the write thread hangs in the 
> first mutex_lock(&f->sem). The cause seems to be an AB-BA deadlock:

When retesting, I found that the write thread hangs in the _second_ 
mutex_lock(&f->sem), i.e., the one for jffs2_do_readpage_nolock(); looking 
at my notes, I am pretty sure that this was also the case in the first 
deadlocks.

Actually, it seems that the path with jffs2_reserve_space() is never taken 
in the 'scp' tests. For testing the patch, I would like to make sure that 
this path also works, but so far, I couldn't find a way to force jffs2 to 
take it. I will have to dig a bit deeper for this ...

Best regards,
Thomas