Re: [PATCH 0/2] taskstats: fix cgroupstats invalid fd handling and add selftests

[Andrew Morton <akpm@linux-foundation.org>]

On Sat, 11 Jul 2026 04:07:35 +0800 Yiyang Chen <cyyzero16@gmail.com> wrote:

> This series fixes an issue where cgroupstats mishandles invalid file
> descriptors, and introduces a functional kselftest to prevent regressions.
> 
> When an invalid file descriptor is passed via CGROUPSTATS_CMD_ATTR_FD,
> cgroupstats_user_cmd() returns 0 instead of an error code. This leads to
> two broken behaviors depending on netlink flags:
> - Callers without NLM_F_ACK block indefinitely on recv().
> - Callers with NLM_F_ACK receive a misleading success ACK (errno == 0)
>   but no actual statistics payload.
> 
> The first patch addresses this by returning -EBADF when the fd cannot be
> resolved. The second patch adds a comprehensive kselftest covering both
> the valid cgroup v1 query and the invalid fd paths (with and without
> NLM_F_ACK) to ensure the fixes work as intended.

lgtm, thanks.

It's a little odd to group two unrelated(?) changes in one series like
this.  Oh well, let's not redo things for this.

Should the netlink_open() in taskstats_fill_stats_tgid.c also be
setting that timeout?  If so, we can share a single implementation - a
little cleanup.

There's a lot of code duplication in selftests/ :(