On OpenSuse 12.1 my system freezes if I write big files to a NFS file system. After completion of the write I can use my system again. An ls of the file written to hangs until the writing is completing. Using programs such as firefox causes kde to hang. I can switch (mostly) to a console and can login via ssh. My assumption is that also firefox does something that requires the nfs write to complete. Attached is part of the log file including Sysrq-w.
Created attachment 72145 [details] Part of syslog including sysrq-w
Known issue. It is due to your 'ls' doing a 'stat()' call which requires the kernel to write out the file first in order to get the POSIXly correct mtime and ctime.
And it is tolerated that this issue can freeze a whole computer (not only ls)for an hour? If so, why not introduce the same behaviour into http and ftp?
It can't "freeze a whole computer". It will freeze the process that is stating the file. Blame POSIX for requiring stat() to return the kitchen sink instead of just returning the stuff that is relevant to the application.., http and ftp aren't filesystems, don't support asynchronous behaviour, and are not required to support POSIX semantics.
I can confirm the reported behavior. The Desktop (kde4) seems to freeze more and more, the more one tries to work with it. One time also mouse movements were frozen. And this happens to completely unrelated tasks. However login via ssh still works, and one gets errors from the kernel, that tasks are blocked for more than X seconds. I think, this bug is a duplicate of bug 43110. So it should not marked as "will not fix" but as duplicate. Also from http://ubuntuforums.org/archive/index.php/t-1478413.html i think this bug has been reintroduced in Kernel 3.X.