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| author |   Fenghua Yu <fenghua.yu@intel.com> | 2020-12-17 14:31:19 -0800 |
|---|---|---|
| committer |   Borislav Petkov <bp@suse.de> | 2021-01-08 09:08:03 +0100 |
| commit | a0195f314a25582b38993bf30db11c300f4f4611 (patch) | |
| tree | 64fa158d93d3c5b1ccf2ff5d59a5327155a9a8fc /arch/x86/kernel/cpu/resctrl/rdtgroup.c | |
| parent | x86/resctrl: Use an IPI instead of task_work_add() to update PQR_ASSOC MSR (diff) | |
| download | linux-dev-a0195f314a25582b38993bf30db11c300f4f4611.tar.xz linux-dev-a0195f314a25582b38993bf30db11c300f4f4611.zip | |
x86/resctrl: Don't move a task to the same resource group
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/
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
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/cpu/resctrl/rdtgroup.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 1c6f8a60ac52..460f3e0df106 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -546,6 +546,13 @@ 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. |