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Fri, 20 Sep 2024 04:15:32 +0200 Message-ID: <177646b0c427786c90a8ccb67f5b956a12759d3a.camel@gmx.de> Subject: Re: [patch] Re: [PowerPC][Linux-next][6.11.0-rc4-next-20240820] OOPs while running LTP FS Stress From: Mike Galbraith To: Venkat Rao Bagalkote , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, peterz@infradead.org, vschneid@redhat.com, mingo@kernel.org, sfr@canb.auug.org.au Date: Fri, 20 Sep 2024 04:15:30 +0200 In-Reply-To: References: <82b9c434-a0fd-4488-95be-a45b8cd4b6e6@linux.vnet.ibm.com> <2fb24ab402d9de45e3cf16e6ba0ad23a7843e5c1.camel@gmx.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.4 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:dsBviHucoPVCIAkRArCXYTRRur6moHQ5PlWxYDaBZ/fY83nVrrz PpGRUkO2aYEq04jy2P6KV61taffA/FL1dP3Ddl/QYoQQygpZWYXqEjX19bZIlBl9H0vI8Fr Bb3X1azisbO0yzKFabdrMc6m9Na0+qdgsngTYcd45yZLLUg+dJMYhdnHSlEvgHTBKam33VV 0z5mri6YzM0GfjmCJppBQ== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:uU4RwNwuQQ4=;HMoPORW2k0gmhOpMNeplNIdw237 eBC1OeCI5+eqnWE3mlqOHHlOTAz+VgXM4Fz+cTHzgp8W2iKsadEf5blNuwxkns9GCGlOGMW4D zMRSS6W322hb6k7ONkrBK1qnoIEnncCgblIjTkSaeEGewqF/BHGgKTRRZ1Ixabvw7FvFpFQm0 TQ31cBzUe1qssaaLReH3zw3RvmkWJ2JBq+X8kCuYI+48H7/WmL3n+WcYMFs1GM31iocG3KK1y ieOb7YgbGLfwYUGzVB46v5IZdDrCslr83zMd9exGZ57iZXagyKAyEZ6oLMHjxerAUUiuaq9cE TtLsn/+h5fejeaNousRwFP40lusW7SXFqncCh8mInmCFZT+Lu+8KpVfKsYO6kLn0X6t/5VIQ2 x7eI0fhTaIwWMb+qWcSihzvK3CF+S1ysTkyqG5yWO5HQLysVqyypghwRT4Mf0t8+I5jn54URI jfAzU2UDlAsupTYLwCjjt6KoOquvSngfbqQd6ow9KCtFMyhqXrGTbmVZHaKL7R8IVLV2OfWwe ypuxeUUUxhGasTOnpd68plojWvZ/olA882yauajmLtwfK3kc/iIVgb3PWi/rU4D6gws6zw3ME YVT81r1525tn5u5XMkIcdZ/RMPRlP0/2FjwVIK5PPXbi3fLeoZivMCfKji8GiJfmVJQSgc/P3 iIdaoNeJHDErHNqvRfVHcaATudW5Wa3ksvIFIFdBOQCSfxmcgFkVRsWioK0K/P3s7wYSzKDzZ E8VWED3HLvjyhhPp5vXqUQnjefyBVpXauOAJnB+Y/cBp57P4AobaKTCFnpgd0P3bg/gvqq77n e9WUb8yI7neMw4gy2Y8XK7Cw== On Thu, 2024-09-19 at 20:09 +0530, Venkat Rao Bagalkote wrote: > > Please add the below tags. > > > Reported-by: Venkat Rao Bagalkote > > Tested-by: Venkat Rao Bagalkote Sure, and while at it I can brush patchlet's rather scruffy fur. 1. on_rq being implied by sched_delayed, redundant check can go. 2. no tasks anywhere in sight, DEQUEUE_SPECIAL can go. 3. use of unlikely in an unlikely path can also go. No functional change. Too bad everything around there fits in 80 characters, or a couple useless diffstat plus signs could go too. sched: Fix sched_delayed vs cfs_bandwidth Meeting an unfinished DELAY_DEQUEUE treated entity in unthrottle_cfs_rq() leads to a couple terminal scenarios. Finish it first, so ENQUEUE_WAKEUP can proceed as it would have sans DELAY_DEQUEUE treatment. Fixes: 152e11f6df29 ("sched/fair: Implement delayed dequeue") Reported-by: Venkat Rao Bagalkote Tested-by: Venkat Rao Bagalkote Signed-off-by: Mike Galbraith =2D-- kernel/sched/fair.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) =2D-- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6049,10 +6049,13 @@ void unthrottle_cfs_rq(struct cfs_rq *cf for_each_sched_entity(se) { struct cfs_rq *qcfs_rq =3D cfs_rq_of(se); - if (se->on_rq) { - SCHED_WARN_ON(se->sched_delayed); + /* Handle any unfinished DELAY_DEQUEUE business first. */ + if (se->sched_delayed) { + int flags =3D DEQUEUE_SLEEP | DEQUEUE_DELAYED; + + dequeue_entity(qcfs_rq, se, flags); + } else if (se->on_rq) break; - } enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP); if (cfs_rq_is_idle(group_cfs_rq(se)))