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| author | Fenghua Yu <fenghua.yu@intel.com> | 2021-01-11 15:16:26 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-01-17 14:04:20 +0100 |
| commit | aa9a5d9640d6bc1ecf25cd465459bb7520272f8c (patch) | |
| tree | a668a15543d0163fa513025037ac7b82ba202265 | |
| parent | 420646bfc8cc90b179c5e4590e2ebb3a113d378e (diff) | |
| download | linux-stable-aa9a5d9640d6bc1ecf25cd465459bb7520272f8c.tar.gz linux-stable-aa9a5d9640d6bc1ecf25cd465459bb7520272f8c.tar.bz2 linux-stable-aa9a5d9640d6bc1ecf25cd465459bb7520272f8c.zip | |
x86/resctrl: Don't move a task to the same resource group
commit a0195f314a25582b38993bf30db11c300f4f4611 upstream
Shakeel Butt reported in [1] that a user can request a task to be moved
to a resource group even if the task is already in the group. It just
wastes time to do the move operation which could be costly to send IPI
to a different CPU.
Add a sanity check to ensure that the move operation only happens when
the task is not already in the resource group.
[1] https://lore.kernel.org/lkml/CALvZod7E9zzHwenzf7objzGKsdBmVwTgEJ0nPgs0LUFU3SN5Pw@mail.gmail.com/
Backporting notes:
Since upstream commit fa7d949337cc ("x86/resctrl: Rename and move rdt
files to a separate directory"), the file
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c has been renamed and moved to
arch/x86/kernel/cpu/resctrl/rdtgroup.c.
Apply the change against file arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
for older stable trees.
Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files")
Reported-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/962ede65d8e95be793cb61102cca37f7bb018e66.1608243147.git.reinette.chatre@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index 262a80f1f2e2..f406e3b85bdb 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -554,6 +554,13 @@ static void update_task_closid_rmid(struct task_struct *t) static int __rdtgroup_move_task(struct task_struct *tsk, struct rdtgroup *rdtgrp) { + /* If the task is already in rdtgrp, no need to move the task. */ + if ((rdtgrp->type == RDTCTRL_GROUP && tsk->closid == rdtgrp->closid && + tsk->rmid == rdtgrp->mon.rmid) || + (rdtgrp->type == RDTMON_GROUP && tsk->rmid == rdtgrp->mon.rmid && + tsk->closid == rdtgrp->mon.parent->closid)) + return 0; + /* * Set the task's closid/rmid before the PQR_ASSOC MSR can be * updated by them. |