Bug 42626 - Laptop freezes when writing big files on NFS
Summary: Laptop freezes when writing big files on NFS
Status: RESOLVED WILL_NOT_FIX
Alias: None
Product: File System
Classification: Unclassified
Component: NFS (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: Trond Myklebust
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2012-01-21 17:15 UTC by b4458835
Modified: 2012-06-12 07:03 UTC (History)
1 user (show)

See Also:
Kernel Version: 3.1.0
Subsystem:
Regression: No
Bisected commit-id:


Attachments
Part of syslog including sysrq-w (79.73 KB, application/octet-stream)
2012-01-21 17:16 UTC, b4458835
Details

Description b4458835 2012-01-21 17:15:29 UTC
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.
Comment 1 b4458835 2012-01-21 17:16:47 UTC
Created attachment 72145 [details]
Part of syslog including sysrq-w
Comment 2 Trond Myklebust 2012-01-21 20:25:40 UTC
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.
Comment 3 b4458835 2012-01-22 21:15:09 UTC
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?
Comment 4 Trond Myklebust 2012-01-22 22:33:41 UTC
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.
Comment 5 flo 2012-06-12 07:03:32 UTC
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.

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