From: Stanislaw Gruszka Date: Tue, 30 Apr 2013 09:35:06 +0000 (+0200) Subject: sched: Avoid prev->stime underflow X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~56^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=68aa8efcd1ab961e4684ef5af32f72a6ec1911de;p=pandora-kernel.git sched: Avoid prev->stime underflow Dave Hansen reported strange utime/stime values on his system: https://lkml.org/lkml/2013/4/4/435 This happens because prev->stime value is bigger than rtime value. Root of the problem are non-monotonic rtime values (i.e. current rtime is smaller than previous rtime) and that should be debugged and fixed. But since problem did not manifest itself before commit 62188451f0d63add7ad0cd2a1ae269d600c1663d "cputime: Avoid multiplication overflow on utime scaling", it should be threated as regression, which we can easily fixed on cputime_adjust() function. For now, let's apply this fix, but further work is needed to fix root of the problem. Reported-and-tested-by: Dave Hansen Cc: # 3.9+ Signed-off-by: Stanislaw Gruszka Cc: Frederic Weisbecker Cc: rostedt@goodmis.org Cc: Linus Torvalds Cc: Dave Hansen Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1367314507-9728-3-git-send-email-sgruszka@redhat.com Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed