On Fri, 2013-06-14 at 02:30 +0100, Ben Hutchings wrote: > On Tue, 2013-06-11 at 12:35 -0700, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > This is a note to let you know that I've just added the patch titled > > > > xen/smp: Fixup NOHZ per cpu data when onlining an offline CPU. > > > > to the 3.9-stable tree which can be found at: > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > The filename of the patch is: > > xen-smp-fixup-nohz-per-cpu-data-when-onlining-an-offline-cpu.patch > > and it can be found in the queue-3.9 subdirectory. > > > > If you, or anyone else, feels it should not be added to the stable tree, > > please let <stable@xxxxxxxxxxxxxxx> know about it. > [...] > > That was OK (albeit the API for play_dead assumes that the CPU > > stays dead and never returns) but with commit 4b0c0f294 > > (tick: Cleanup NOHZ per cpu data on cpu down) that is no longer safe > > as said commit resets the ts->inidle which at the start of the > > cpu_idle loop was set. > [...] > > This also needs to be applied to earlier branches, because commit > 4b0c0f294 was applied to all of them: > > 2.6.32: d31e3b9 tick: Cleanup NOHZ per cpu data on cpu down > 3.0: b9cbfd2 tick: Cleanup NOHZ per cpu data on cpu down > 3.2: d9202d6 tick: Cleanup NOHZ per cpu data on cpu down > 3.4: 33b7cfc tick: Cleanup NOHZ per cpu data on cpu down > 3.9: c25c0eb tick: Cleanup NOHZ per cpu data on cpu down ...though, at least for 3.2, it's not at all obvious how to backport it as tick_nohz_idle_enter() doesn't exist. Konrad, can you provide a backport of this, or should the backported commit 4b0c0f294 be reverted in older stable branches? Ben. -- Ben Hutchings If the facts do not conform to your theory, they must be disposed of.
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