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Mon, 4 May 2026 12:31:56 +0000 (GMT) Date: Mon, 4 May 2026 14:31:56 +0200 From: Vasily Gorbik To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Cc: Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , John Stultz , "Connor O'Brien" , Vineeth Pillai , Joel Fernandes , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/1] sched/core: Don't steal a proxy-exec donor Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Patchwork-Bot: notify X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: _Ff3VtXVSgZv7xaBjyMJzC1FekwiwOA9 X-Proofpoint-GUID: 9poBvFVV01zDoEmHz-gTwNdvL_FRhk2Z X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA0MDEyOSBTYWx0ZWRfXxt5CFJc5jSF4 6GHeWkLTHtdjipm1yTlV/NOvaRTB2j6LDIY9nOxDstCz5Cau3wN7E8C3vUJIc+wfbx9LyqZV5aq d/DCXpmA9HYjnvZnDUdmFbORIn+lIFHNaTUvBheWn7WomM5KRlLCaeSvPaxSzlQpQEFEQ4N1NJ/ wU01zYoQ5d0bhPP1i4xwVbijBHKmZckE+7jksUrOzavFOLWQ/0h6c5fPti9oxtOF0NPrYRxXdbn vxsR8z/E4FKdEHSEi27m4MDQI7P/dERiuakKr38a6+QkZbx9s6ge429pRV6fGZv9RcLyHQjgYHy 3t8CE8jF1umQacokqdCXWPatEbMS84IP+8tKbMhthWnsKP/nEzDkd1MuHyIzLl5Jk3lScU+Cy8B wiEItR8OfhkYToub6f6TwFMGNpG+wLxw1YCCjK9kYGz8lt6m6YIhK2smCtPShFYMG6hmRHy+OCF 2aj3EM23L67m+o0/3Pg== X-Authority-Analysis: v=2.4 cv=UbFhjqSN c=1 sm=1 tr=0 ts=69f891c0 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=OAnpjWcG7tVGC2mqRyQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-04_04,2026-04-30_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 adultscore=0 priorityscore=1501 bulkscore=0 phishscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605040129 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" try_steal_cookie() avoids stealing src->core_pick and src->curr before moving a task with the same cookie via move_queued_task_locked(). With proxy-exec, src->donor is the current scheduling context and may differ from src->curr. Stealing it migrates a task that the source rq still treats as current. For CFS, src cfs_rq->curr is left pointing at the stolen entity and the next pick on src hits the WARN_ON_ONCE in put_prev_entity(). Commit 7de9d4f94638 ("sched: Start blocked_on chain processing in find_proxy_task()") tweaked the fair class logic so that the donor task isn't migrated away while running the proxy. Do it similarly for try_steal_cookie() and skip src->donor as well. Fixes: 7de9d4f94638 ("sched: Start blocked_on chain processing in find_prox= y_task()") Signed-off-by: Vasily Gorbik --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index b8871449d3c6..3cf5fb70814c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6358,7 +6358,7 @@ static bool try_steal_cookie(int this, int that) return false; =20 do { - if (p =3D=3D src->core_pick || p =3D=3D src->curr) + if (p =3D=3D src->core_pick || p =3D=3D src->curr || p =3D=3D src->donor) goto next; =20 if (!is_cpu_allowed(p, this)) --=20 2.53.0