Re: [PATCH v2] exit: fix lost-update race on the child_subreaper bitfields

[Christian Brauner]

On Sun, 11 Oct 2026 08:34:39 -0400, Nickolai Zeldovich wrote:
> is_child_subreaper, has_child_subreaper, autoreap and, with
> CONFIG_POSIX_TIMERS=y, timer_create_restore_ids are 1-bit fields that
> share one memory location in struct signal_struct.  A store to any of
> them is a read-modify-write of the whole word, and three of the stores
> run without a common lock:
> 
>   - PR_SET_CHILD_SUBREAPER writes me->signal->is_child_subreaper with
>     no lock held.
> 
> [...]

Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fixes

[1/1] exit: fix lost-update race on the child_subreaper bitfields
      https://git.kernel.org/vfs/vfs/c/56d5dcb2d6d5