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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-1.fc44) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2026-08-28 at 12:24 -0700, Shakeel Butt wrote: > Sashiko [1] reported that memcg_hotplug_cpu_dead() drains the stocks > of the CPU which went away but leaves FLUSHING_CACHED_CHARGE alone. >=20 > The flag can be set at that point: drain_all_stock() may have claimed > the stock and queued the drain work shortly before the CPU went down. > workqueue_offline_cpu() unbinds the per-cpu workers, so such a > pending > work item is executed by an unbound worker on some other CPU, where > drain_local_memcg_stock() operates on this_cpu_ptr() and thus drains > and clears the flag of that other CPU instead.=C2=A0 Nothing clears the > flag > of the dead CPU, so drain_all_stock() would skip its stock forever > once > the CPU comes back online. >=20 > Clear the flag of both stocks after draining them. >=20 > Signed-off-by: Shakeel Butt > Reported-by: Sashiko > Link: > https://sashiko.dev/#/patchset/20260828135036.7d44361f%40fangorn=C2=A0[1] > --- >=20 Funny, my AI came up with the same solution, and I just asked it to do a safety analysis on it. It was quite thorough. Reviewed-by: Rik van Riel --=20 All Rights Reversed.