Mounts to Windows 7 and "out of memory" or "insufficient server resources"

Jeff Layton jlayton at
Wed Sep 28 06:00:27 MDT 2011

On Tue, 27 Sep 2011 16:36:22 -0500
Steve French <smfrench at> wrote:

> FYI - The cifs async write in 3.0 seems to exacerbate problems running
> out of memory (apparently) on the Windows 7 system (running as a
> server) after a large file copy to the server completes.   I have been
> able to reproduce the same problem on Windows Vista Service Pack 2
> (which is a good news/bad news story since my earlier testing on
> Windows Vista showed hangs on some requests rather than returning out
> of memory).  Does not seem to be a problem with any of the Windows
> server versions just Windows 7 and Vista so far.
> As Pavel noted in an earlier note, increasing MaxWorkItems to 4096 in
> the Windows registry solves this.
> The cifs async write code does increase large file copy speed
> dramatically (more than 15% in most environments) - but we are working
> through how to handle the Windows7/WindowsVista problem to see if
> there are workarounds.

This is seems likely to be a cifs.ko bug -- it does not respect the
MaxReq parm that the server sends in the negotiate and instead uses a
hardcoded limit of 50 requests (which is tunable via module parm).

What value is the server sending in the NEGOTIATE? Ensuring that
cifs.ko doesn't exceed that value seems like a worthwhile endeavor.
This is likely to be even worse soon when the async read patches are

Jeff Layton <jlayton at>

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