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Date:      Tue, 9 Dec 1997 00:52:21 +0000 (GMT)
From:      Andrew Gordon <arg@arg1.demon.co.uk>
To:        "John S. Dyson" <dyson@freebsd.org>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: kern/2573 - NFS hangs with mmap() - on current too!
Message-ID:  <Pine.BSF.3.91.971209002512.24781A-100000@server.arg.sj.co.uk>
In-Reply-To: <199712071525.KAA01275@dyson.iquest.net>

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Seems my latching onto kern/2573 was a mistake - having reduced my 
application to a short test program and tried it on -current, the problem 
occurs there too.

Although the main problem is with the NFS client machine hanging, there is 
also something odd going on at the server end too: the first time I run 
this program the client hangs fairly rapidly, with no diagnostics.  
Subsequently (client rebooted), the program will run for a while, but 
produces lots of kernel printfs:

vnode_pager_putpages: I/O error 13
vnode_pager_putpages: Residual I/O xxxxx at yyyy

(where xxxxx is a multiple of 4096, up to 65536, yyyy is an arbitrary 
number in the range 100..400).

The errors are indeed real errors from the NFS server:

23:19:00.487718 nt.arg.sj.co.uk.c7c71f72 > rocket.arg.sj.co.uk.nfs: 1472 
write fh 0,197638/38573 8192 bytes @ 114688 (frag 4053:1480@0+)
23:19:00.489151 nt.arg.sj.co.uk > rocket.arg.sj.co.uk: (frag 4053:1480@1480+)
23:19:00.490385 nt.arg.sj.co.uk > rocket.arg.sj.co.uk: (frag 4053:1480@2960+)
23:19:00.491613 nt.arg.sj.co.uk > rocket.arg.sj.co.uk: (frag 4053:1480@4440+)
23:19:00.492845 nt.arg.sj.co.uk > rocket.arg.sj.co.uk: (frag 4053:1480@5920+)
23:19:00.493619 nt.arg.sj.co.uk > rocket.arg.sj.co.uk: (frag 4053:912@7400)
23:19:00.493834 rocket.arg.sj.co.uk.nfs > nt.arg.sj.co.uk.c7c71f72: reply 
ok 60 write ERROR: 'Permission denied'
23:19:00.494855 nt.arg.sj.co.uk.c7c71f73 > rocket.arg.sj.co.uk.nfs: 1472 
write fh 0,197638/38573 4096 bytes @ 135168 (frag 4054:1480@0+)
23:19:00.496290 nt.arg.sj.co.uk > rocket.arg.sj.co.uk: (frag 4054:1480@1480+)
23:19:00.497342 nt.arg.sj.co.uk > rocket.arg.sj.co.uk: (frag 4054:1256@2960)
23:19:00.497667 rocket.arg.sj.co.uk.nfs > nt.arg.sj.co.uk.c7c71f73: reply 
ok 60 write ERROR: 'Permission denied'


The client will run for quite a long time with these log messages spewing 
out on the console (I stopped for dinner and it was still going), but it 
can be provoked into hanging up by stimulating some other activity.
Rebooting the server makes the errors go away on the next run, then they
come back.  This isn't related to the creation of the files: the same
thing happens whether the files are deleted and re-created by the 
program, or are pre-created using dd, or are left over from a previous run.
The files have 664 access, and are owned by the same (not root) user
as is running the program.



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