Re: FAILED: patch "[PATCH] posix-cpu-timers: fix race between handle_posix_cpu_timers()" failed to apply to 5.4-stable tree

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: f90fff1e152dedf52b932240ebbd670d83330eca

Status in newer kernel trees:
6.15.y | Present (different SHA1: d65f6c68f7b1)
6.12.y | Present (different SHA1: 18a3e65f32ed)
6.6.y | Present (different SHA1: 8db5813e9ad7)
6.1.y | Present (different SHA1: 61fa08967f27)
5.15.y | Present (different SHA1: f6e90a3258e0)
5.10.y | Present (different SHA1: 1c179c7c3b82)

Note: The patch differs from the upstream commit:
---
1:  f90fff1e152de ! 1:  933e5cbcf266c posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()
    @@ Metadata
     Author: Oleg Nesterov <oleg@redhat.com>
     
      ## Commit message ##
    -    posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()
    +    FAILED: patch "[PATCH] posix-cpu-timers: fix race between handle_posix_cpu_timers()" failed to apply to 5.4-stable tree
    +
    +    On 06/17, gregkh@linuxfoundation.org wrote:
    +    >
    +    > The patch below does not apply to the 5.4-stable tree.
    +
    +    Please see the attached patch for 5.4.y
    +
    +    Oleg.
    +
    +    From a3dbb5447bc9a8f9c04ffa5381b0a0bd77b1bdd5 Mon Sep 17 00:00:00 2001
    +    From: Oleg Nesterov <oleg@redhat.com>
    +    Date: Tue, 17 Jun 2025 19:15:50 +0200
    +    Subject: [PATCH 5.4.y] posix-cpu-timers: fix race between
    +     handle_posix_cpu_timers() and posix_cpu_timer_del()
    +    MIME-Version: 1.0
    +    Content-Type: text/plain; charset=UTF-8
    +    Content-Transfer-Encoding: 8bit
    +
    +    commit f90fff1e152dedf52b932240ebbd670d83330eca upstream.
     
         If an exiting non-autoreaping task has already passed exit_notify() and
         calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent
    @@ kernel/time/posix-cpu-timers.c: void run_posix_cpu_timers(void)
     +		return;
     +
      	/*
    - 	 * If the actual expiry is deferred to task work context and the
    - 	 * work is already scheduled there is no point to do anything here.
    + 	 * The fast path checks that there are no expired thread or thread
    + 	 * group timers.  If that's so, just return.
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.4.y        |  Success    |  Success   |