On 2025/1/24 1:47, Abel Wu wrote:
> The commit b824766504e4 ("cgroup/rstat: add force idle show helper")
> retrieves forceidle_time outside cgroup_rstat_lock for non-root cgroups
> which can be potentially inconsistent with other stats.
>
> Rather than reverting that commit, fix it in a way that retains the
> effort of cleaning up the ifdef-messes.
>
> Fixes: b824766504e4 ("cgroup/rstat: add force idle show helper")
> Signed-off-by: Abel Wu <wuyun.abel@xxxxxxxxxxxxx>
> ---
> kernel/cgroup/rstat.c | 29 +++++++++++++----------------
> 1 file changed, 13 insertions(+), 16 deletions(-)
>
> diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
> index 5877974ece92..c2784c317cdd 100644
> --- a/kernel/cgroup/rstat.c
> +++ b/kernel/cgroup/rstat.c
> @@ -613,36 +613,33 @@ static void cgroup_force_idle_show(struct seq_file *seq, struct cgroup_base_stat
> void cgroup_base_stat_cputime_show(struct seq_file *seq)
> {
> struct cgroup *cgrp = seq_css(seq)->cgroup;
> - u64 usage, utime, stime, ntime;
> + struct cgroup_base_stat bstat;
>
> if (cgroup_parent(cgrp)) {
> cgroup_rstat_flush_hold(cgrp);
> - usage = cgrp->bstat.cputime.sum_exec_runtime;
> + bstat = cgrp->bstat;
Thank you for finding that.
In my version 2, I used to assign cgrp->bstat to bstat.
This is Tj's comment:
https://lore.kernel.org/linux-kernel/ZoQ2ti7nnz9EJSc3@xxxxxxxxxxxxxxx/
Best regards,
Ridong
> cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
> - &utime, &stime);
> - ntime = cgrp->bstat.ntime;
> + &bstat.cputime.utime, &bstat.cputime.stime);
> cgroup_rstat_flush_release(cgrp);
> } else {
> - /* cgrp->bstat of root is not actually used, reuse it */
> - root_cgroup_cputime(&cgrp->bstat);
> - usage = cgrp->bstat.cputime.sum_exec_runtime;
> - utime = cgrp->bstat.cputime.utime;
> - stime = cgrp->bstat.cputime.stime;
> - ntime = cgrp->bstat.ntime;
> + root_cgroup_cputime(&bstat);
> }
>
> - do_div(usage, NSEC_PER_USEC);
> - do_div(utime, NSEC_PER_USEC);
> - do_div(stime, NSEC_PER_USEC);
> - do_div(ntime, NSEC_PER_USEC);
> + do_div(bstat.cputime.sum_exec_runtime, NSEC_PER_USEC);
> + do_div(bstat.cputime.utime, NSEC_PER_USEC);
> + do_div(bstat.cputime.stime, NSEC_PER_USEC);
> + do_div(bstat.ntime, NSEC_PER_USEC);
>
> seq_printf(seq, "usage_usec %llu\n"
> "user_usec %llu\n"
> "system_usec %llu\n"
> "nice_usec %llu\n",
> - usage, utime, stime, ntime);
> + bstat.cputime.sum_exec_runtime,
> + bstat.cputime.utime,
> + bstat.cputime.stime,
> + bstat.ntime);
>
> - cgroup_force_idle_show(seq, &cgrp->bstat);
> + cgroup_force_idle_show(seq, &bstat);
> }
>
> /* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
