On Tue, Aug 21, 2012 at 10:20:31AM +0400, Michael Tokarev wrote: > On 21.08.2012 02:37, J. Bruce Fields wrote: > > From: "J. Bruce Fields" <bfields@xxxxxxxxxx> > > > > The rpc server tries to ensure that there will be room to send a reply > > before it receives a request. > > > > It does this by tracking, in xpt_reserved, an upper bound on the total > > size of the replies that is has already committed to for the socket. > > > > Currently it is adding in the estimate for a new reply *before* it > > checks whether there is space available. If it finds that there is not > > space, it then subtracts the estimate back out. > > > > This may lead the subsequent svc_xprt_enqueue to decide that there is > > space after all. > > > > The results is a svc_recv() that will repeatedly return -EAGAIN, causing > > server threads to loop without doing any actual work. > > > > Cc: stable@xxxxxxxxxxxxxxx > > This is applicable to all 3.0+ stable kernels. The commit which > made this bug apparent is included into 3.0-rc5 (changing memory > buffer sizes for tcp/udp/stcp). Before that commit, this bug is > not triggered, at least here. So 3.0, 3.2, 3.4 and 3.5 (for which > stable series are maintained at the moment) definitely should > include it. > > Should it be applied to 2.6.32 &Co too? Probably. It doesn't apply cleanly as is, though, so I suspect the stable cc won't be enough to get it applied by default (that may be true of the some the more recent kernels too, I haven't checked). If you want to be sure that would happen, test and post a backported patch and I'll make sure it gets to Greg. --b. > > /mjt > > > Reported-by: Michael Tokarev <mjt@xxxxxxxxxx> > > Tested-by: Michael Tokarev <mjt@xxxxxxxxxx> > > Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
