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Thu, 11 Sep 2025 08:38:02 +0000 (GMT) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 11 Sep 2025 10:38:02 +0200 Message-Id: Cc: , , , , , , , , , , Subject: Re: [PATCH v2 03/20] KVM: s390: Add gmap_helper_set_unused() From: "Nico Boehr" To: "Claudio Imbrenda" , X-Mailer: aerc 0.20.1 References: <20250910180746.125776-1-imbrenda@linux.ibm.com> <20250910180746.125776-4-imbrenda@linux.ibm.com> In-Reply-To: <20250910180746.125776-4-imbrenda@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTA2MDAxMCBTYWx0ZWRfX9eiJqfYVwXN3 7C63COfO56is7R+5SGoXY1ZfCYbcctKhEsElr+QMh6phIVpqL/mCIYyXogyljZoKVrIHgVGnK3u veHBkmunoLnMCHzTkBWyNsqfMbiD/Y2ym9R6T7tPtOSzJQqCgVmTHlsjSQZBULRZmYJad1pDs4B G+vr58qqETHzuwGC0d8HgEqtQck+uR/pqHasS6Ko+Pf1MFYS06lNRo4aXHpTMXP41c4HjVpKplR RMzfeOjxoBGJCSxTW3d8jlGREaHIG7KkzXgGHZJwms7yX1WkWDdXy9gGzGFVCnCwpb6mOuOQrTV l0vwZ43pyV635EHa4bAmSCohSLlWhYb/GNClJLI2HFrP7j6RvcGyjtSlV+4tbrPz5LJUYCX/shJ 5yyihadV X-Authority-Analysis: v=2.4 cv=SKNCVPvH c=1 sm=1 tr=0 ts=68c28a70 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=yJojWOMRYYMA:10 a=VnNF1IyMAAAA:8 a=WEpOJczLzZDRNqIK8FsA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: r01cRzGd5DCmwe8UDFj4BggK3ysPDNP3 X-Proofpoint-ORIG-GUID: r01cRzGd5DCmwe8UDFj4BggK3ysPDNP3 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-10_04,2025-09-10_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 spamscore=0 priorityscore=1501 bulkscore=0 malwarescore=0 adultscore=0 suspectscore=0 impostorscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509060010 On Wed Sep 10, 2025 at 8:07 PM CEST, Claudio Imbrenda wrote: > Add gmap_helper_set_unused() to mark userspace ptes as unused. > > Core mm code will use that information to discard unused pages instead > of attempting to swap them. > > Signed-off-by: Claudio Imbrenda Reviewed-by: Nico Boehr Tested-by: Nico Boehr I observed 21965 calls to gmap_helper_set_unused() where we were successful= ly traversing the page tables to the PTE; of these 21868 made it to the part w= here _PAGE_UNUSED is set. So _rarely_ we seem to be unable to take the lock (or = the PMD changed under us), but in the majority of cases we make it, so this see= ms fine to me.