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Wed, 16 Sep 2026 09:25:07 +0000 (GMT) Received: from osiris (unknown [9.111.77.138]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Wed, 16 Sep 2026 09:25:07 +0000 (GMT) Date: Wed, 16 Sep 2026 11:25:05 +0200 From: Heiko Carstens To: Mike Rapoport Cc: Vineeth Vijayan , Peter Oberparleiter , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Vlastimil Babka , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 06/13] s390/cmf: Use kmalloc() for the CMB area Message-ID: <20260916092505.15587Ae2-hca@linux.ibm.com> References: <20260910-s390-cio-ready-v2-0-e931086fdde1@kernel.org> <20260910-s390-cio-ready-v2-6-e931086fdde1@kernel.org> <20260914175952.14910Fc6-hca@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE2MDExNiBTYWx0ZWRfX69fUZptnnHUU LrrBMk4p73kYj02sbSnZri/y2AhmHbqevea4IIiaytd0Kq+FJB2PQ/W0U3wmgWlO5WFi+MOvuEV oEkveSBkpOAgaUHmMMwc9cmVp8KN+8BWe6xWmHtDXR56RAmVhCVE2H/SoEvTGpDwuJDvgpi+AFx 1gaxDpuGfCuL+zHWZdN6sQ8fD0VLA62fTeKZA/UxwKXsdCAf802MGlJgVXmS6I3KmY1H69Ig4MP IBY2iq2h8QeCFiZ1AIjfBVlOVvjdoajgMYnvzd8MVWQ7DVVfmawNNRxMw51OJUDu+HO3MIsdo2a 4gaPfomddxQooCUrBSxj4UJ0INoijEAxCcqOvMbUl0IL9K0lgruC89rzkIgzg+I+rNjrNTHIQAj cCOrgpq4wKQtRkZCNtWHbYG7/BfzZBJah5SI3vxXPlrkgBtvPjl/J4lpNLXtlEdOCEvw/HQUQw+ zHKYMUNbh+94N9+NLYw== X-Proofpoint-ORIG-GUID: g8mDs6ZcI7hyKXA-rqQ11cv1ZxLPEDED X-Proofpoint-GUID: g8mDs6ZcI7hyKXA-rqQ11cv1ZxLPEDED X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE2MDExNiBTYWx0ZWRfX71SwQcJHROeH /6MGV/0cYTm5Hq6vhhaLZcR2912LzjWY7QKhUJzheCgdzmrVZzXwocHdeMDW7u4cJ1GJxlq7no5 TVlSmYQKWN4NI5m5xCGkWfCaDzulRwU= X-Authority-Analysis: v=2.4 cv=cY9HPXDM c=1 sm=1 tr=0 ts=6aaa6078 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=jh9rqw0bRQUQ3So_9I0A:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-15_05,2026-09-15_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 bulkscore=0 clxscore=1015 suspectscore=0 impostorscore=0 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609160116 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1097B40002 X-Rspam-User: X-Stat-Signature: 1e35uaxumw5woepr39d1x9ecnt1wkgta X-HE-Tag: 1789550714-50559 X-HE-Meta: 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 Vw+70eDI wMlAWuyDAgtsL2yqgKk4ApF2QqSj062YWXlgWVky5Ae1fsUCzUSNVDnPm00LNCtOo6wX/HQtjYpUAPts9jNrGa9OiV3g5wJFLnn9AX2R57YJZ56dseprB0pwRtdqcpXUaXitd15B+IIw4ZgIj6yS6GPNCY0BN8jcSufHwj7Y2dHTd03ZazNuvL46cdNUQhfh0UbqiPGGYN4kDs10IyM0vPB1wBgcgzSwRV1yC Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 15, 2026 at 09:37:51PM +0300, Mike Rapoport wrote: > On Mon, Sep 14, 2026 at 07:59:52PM +0200, Heiko Carstens wrote: > > On Thu, Sep 10, 2026 at 02:00:08PM +0300, Mike Rapoport (Microsoft) wrote: > > > - mem = (void *)__get_free_pages(GFP_KERNEL, get_order(size)); > > > + mem = kmalloc(size, GFP_KERNEL); > > > spin_lock(&cmb_area.lock); > > > > > > if (cmb_area.mem) { > > > /* ok, another thread was faster */ > > > - free_pages((unsigned long)mem, get_order(size)); > > > + kfree(mem); > > > } else if (!mem) { > > > /* no luck */ > > > ret = -ENOMEM; > > > > This is the only patch which made me raise an eyebrow, since the allocated > > area is smaller. But it looks all good according to the architecture. > > Since the allocation changed anyway, it might also make sense to switch to > > kzalloc() and get rid of the subsequent memset() (not in the context of the > > above diff). > > I suppose separate alloc and memset() are there to save a couple of cycles > when another thread is the first to allocate, no idea how important this is > though :) I don't think this is important. Anyway let's keep this as simple as possible and just do the conversion without any further changes.