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    SubjectRe: [PATCH 0/5] kthread: increase the size of kthread's comm
    On Sun, Oct 3, 2021 at 11:41 AM Al Viro <viro@zeniv.linux.org.uk> wrote:
    >
    > On Wed, Sep 29, 2021 at 11:50:31AM +0000, Yafang Shao wrote:
    >
    > > That motivates me to do this improvement.
    > >
    > > This patch increases the size of ktread's comm from 16 to 24, which is
    > > the same with workqueue's. After this change, the name of kthread can be
    > > fully displayed in /proc/[pid]/comm, for example,
    > >
    > > rcu_tasks_kthread
    > > rcu_tasks_rude_kthread
    > > rcu_tasks_trace_kthread
    > > ecryptfs-kthread
    > > vfio-irqfd-cleanup
    > > ext4-rsv-conversion
    > > jbd2/nvme0n1p2-8
    > > ...
    > >
    > > Because there're only a few of kthreads, so it won't increase too much
    > > memory consumption.
    >
    > That's a bloody massive overkill. If you care about /proc/*/comm, you
    > might want to take a look at the function that generates its contents:
    >
    > void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
    > {
    > char tcomm[64];
    >
    > if (p->flags & PF_WQ_WORKER)
    > wq_worker_comm(tcomm, sizeof(tcomm), p);
    > else
    > __get_task_comm(tcomm, sizeof(tcomm), p);
    >
    > if (escape)
    > seq_escape_str(m, tcomm, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
    > else
    > seq_printf(m, "%.64s", tcomm);
    > }
    >
    > Hint: it's not always p->comm verbatim...

    Right, I found it. That's why I was wondering storing the kthread's
    comm in kthread_data.[1]
    But after Petr's suggestion, I find increasing the size of comm to 24
    for COFNIG_BASE_FULL and keeping it as 16 for COFNIG_BASE_SMALL is a
    better solution.

    [1]. https://lore.kernel.org/lkml/CALOAHbD3HUqUnjMYKX7NGwVWiS4K7OvS6uPNWucnOA5Cy3pn9w@mail.gmail.com/#t

    --
    Thanks
    Yafang

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