Messages in this thread | | | Date | Mon, 19 Jun 2023 10:37:57 -0400 | Subject | Re: [PATCH] cgroup/cpuset: remove unneeded nodes_or() in cpuset_change_task_nodemask() | From | Waiman Long <> |
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On 6/17/23 04:30, Miaohe Lin wrote: > The tsk->mems_allowed is changed before calling mpol_rebind_task() and > being reassigned right after it. But tsk->mems_allowed is not needed > inside mpol_rebind_task(). So remove unneeded tsk->mems_allowed modify > via nodes_or() here. > > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > kernel/cgroup/cpuset.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index 58e6f18f01c1..33a429c1179f 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -1941,7 +1941,6 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk, > local_irq_disable(); > write_seqcount_begin(&tsk->mems_allowed_seq); > > - nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); > mpol_rebind_task(tsk, newmems); > tsk->mems_allowed = *newmems; >
That line was inserted by commit cc9a6c8776615 ("cpuset: mm: reduce large amounts of memory barrier related damage v3"). At first glance, it does looks like it is not necessary. However, I am not sure if a race is possible that will produce a false failure because of missing this line.
My 2 cents.
Cheers, Longman
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