From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21478C36010 for ; Fri, 11 Apr 2025 12:04:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 112862801B3; Fri, 11 Apr 2025 08:04:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0C65128019B; Fri, 11 Apr 2025 08:04:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EA3642801B3; Fri, 11 Apr 2025 08:04:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id CD93E28019B for ; Fri, 11 Apr 2025 08:04:53 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 8A558BD5F6 for ; Fri, 11 Apr 2025 12:04:54 +0000 (UTC) X-FDA: 83321631708.13.BEC8A53 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by imf25.hostedemail.com (Postfix) with ESMTP id 2ADB4A0020 for ; Fri, 11 Apr 2025 12:04:51 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=rg6+7yX1; spf=pass (imf25.hostedemail.com: domain of agordeev@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=agordeev@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744373092; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=PnqGyYgzHT0Sz+5k6BXWUk5N9daIOAt0miBGvgSDKAY=; b=i588tvc8TT0T+2xYSpVe0Ez0kpKimX5fjyhYViASqt1Nw6yBzm8HYjh39NCufJCzdHDXsH pCiRbfRjFB9MB8QrA0p8aCjb/RLE8Ub6CMgTrUEYQL/Cr18O48km1NVT0tC25PI8Uj7I6I GDZIKPpCnJHUkFoYJyXXr+4pdq33Pe8= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=rg6+7yX1; spf=pass (imf25.hostedemail.com: domain of agordeev@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=agordeev@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1744373092; a=rsa-sha256; cv=none; b=oVrqrAEuhGwVYmhaz3e1A7pF0Y28x2jYMepTWwq9YW0ngfQDq1xtIL4gUoNsVDkmSLi0HB 8SkNCgzmrnOgNBgT644+dHA3zAr5+iJQpi4w4EEX1AxgNkYMqNsx4dcwIpahIVeN69zohX jueYKFHLZQR7dKgsn+shMIkd7j60DRM= Received: from pps.filterd (m0360072.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 53B4Hwbv028306; Fri, 11 Apr 2025 12:04:50 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=pp1; bh=PnqGyYgzHT0Sz+5k6BXWUk5N9daIOA t0miBGvgSDKAY=; b=rg6+7yX1oIY/hrDNoGj3DwccvaTK1QnKM/d3OmrcztqEDp j4j5yfP62lfxD/7TrZFOhfyN/XMIoQfZ9vBMmaXQZiQxsA6GTPDm833Y+/EC3OIe EVs/aJqbsqOqPuf9GkcCGI+TAuCYbMSXC3WAuwom/mXn7fzwJevaJwo4QojGds41 jOG6NWCKAmBMEP3STFTm8r6lvpkCTgDuZRyy1CUREkt2rgPkvaChg17e2Fifu4mj LsxtUVPM4U+FemCOiNrQDNqf6JSM0VFG10GCRlIJZfrAUB7AhisPET/LTJCs7Vcx K2jP6Vv5ysev6rq9j6y5SM7EnQ6SgRS4oy8ulnNA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 45xj5xmbq9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 11 Apr 2025 12:04:49 +0000 (GMT) Received: from m0360072.ppops.net (m0360072.ppops.net [127.0.0.1]) by pps.reinject (8.18.0.8/8.18.0.8) with ESMTP id 53BBvsIB009672; Fri, 11 Apr 2025 12:04:49 GMT Received: from ppma11.dal12v.mail.ibm.com (db.9e.1632.ip4.static.sl-reverse.com [50.22.158.219]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 45xj5xmbq7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 11 Apr 2025 12:04:49 +0000 (GMT) Received: from pps.filterd (ppma11.dal12v.mail.ibm.com [127.0.0.1]) by ppma11.dal12v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 53B8Brgm029520; Fri, 11 Apr 2025 12:04:48 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma11.dal12v.mail.ibm.com (PPS) with ESMTPS id 45x1k78q3q-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 11 Apr 2025 12:04:48 +0000 Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 53BC4kR641484682 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 11 Apr 2025 12:04:46 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8519420043; Fri, 11 Apr 2025 12:04:46 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 975B920040; Fri, 11 Apr 2025 12:04:45 +0000 (GMT) Received: from li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com (unknown [9.171.62.45]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTPS; Fri, 11 Apr 2025 12:04:45 +0000 (GMT) Date: Fri, 11 Apr 2025 14:04:44 +0200 From: Alexander Gordeev To: Nicholas Piggin Cc: Andrew Morton , Andrey Ryabinin , Hugh Dickins , Guenter Roeck , Juergen Gross , Jeremy Fitzhardinge , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v1 0/4] mm: Fix apply_to_pte_range() vs lazy MMU mode Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-GUID: G_BAGoiaaveYky3440tvomTW6sZpx75k X-Proofpoint-ORIG-GUID: 0HKwRFIDMdOHgUv5TCoToIJxhDHz4gm6 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-04-11_04,2025-04-10_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 spamscore=0 malwarescore=0 bulkscore=0 phishscore=0 mlxscore=0 suspectscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 mlxlogscore=591 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2504110077 X-Rspamd-Queue-Id: 2ADB4A0020 X-Stat-Signature: 3fpb5qrpfcqk6cdcngqc73dio7n6yqzz X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1744373091-71858 X-HE-Meta: U2FsdGVkX19vAvlc6GBvf5ixC7k8qyISLDcN0Gt4wiLoMSRDe4mc1yOCtKcJsd3aYC8vIxz/7Z+onk/aY20HxGOEjz44Wg7c/RYBwgXPvoiidwmvzQFVXntH7sZlr0JtVht0r4oG30gbOeTjN8DDp1i1tF803RhlszLW/p89la9OYNMbHyjVRVShLizBs+aqcfr9uk7HjF3Sy06STMWSAbNTA04GSPFZwHXjHKPYZX/w9RihWKPxuFMIXeZwPmgEaTezvbr1oEBcY3fkKCE7xF2bYObxbhEyZdWikT3vZfvehm2mwxkPgsTgX8WYi4UbYcckIBTitTex87/3Q+gp2HFOYlpg+nmhika8rWHy/As7ZaY+84rPR3PrCILPANTaXHgV/47rOBZWpa8fki+0+KupbbtEmDuKN9PJnhIPiuZHHiLmefp8S0UKN8f8Sj9CKaBJ1gDe7xJxm5QRLmnt6rPy2JTCp3QUgZ23IvPYMgLG5hJ4DfS/NN+7dpS+sAgI4F+TgpOctJY77cZxMq1j0LeVgG3PCqJogmpKXqnGJhGDAd1hbIc9mOg2pkGMsqS3+yrrOekzoVyY7NGYvFm9hOL3z8q+RK5efaOd01WG+e54yCnMeQDFxTHxek7TKbqbhuxUSSJeJ6VI7X7/+s61gGAvG59Mqyt4atXY0xzmzN7q+W659UIayzbkl+I9r6h7Y+nvtwUGQnc0aF8TOl53qWc9xJrrbVhvKRLnqamY6Hy5sUbpsKBsJAAEB95vMHN5fAn7Xwxi3YVsm2i2ZgX3w015ZQBzcHfq8ebcWByVeiJC5wTYoeRc2HZoyrc/fV4XKurgPfnoung4NEhvT7CE2u1wY1OAWksqrJ/JyZ5bqSkLj8XgAgHvEiibR7tOtbCecbUAwPtuBAIOSDnQtsF0JIur5e8JPtsU8LbRs+e+EWnuKoDxZ4FLGXPXqkFz6Cj/hgifve+c+v3hwsXn5UY pS847Rxt 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 11, 2025 at 05:12:28PM +1000, Nicholas Piggin wrote: ... > Huh. powerpc actually has some crazy code in __switch_to() that is > supposed to handle preemption while in lazy mmu mode. So we probably > don't even need to disable preemption, just use the raw per-cpu > accessors (or keep disabling preemption and remove the now dead code > from context switch). Well, I tried to do the latter ;) https://lore.kernel.org/linuxppc-dev/3b4e3e28172f09165b19ee7cac67a860d7cc1c6e.1742915600.git.agordeev@linux.ibm.com/ Not sure how it is aligned with the current state (see below). > IIRC all this got built up over a long time with some TLB flush > rules changing at the same time, we could probably stay in lazy mmu > mode for a longer time until it was discovered we really need to > flush before dropping the PTL. > > ppc64 and sparc I think don't even need lazy mmu mode for kasan (TLBs > do not require flushing) and will function just fine if not in lazy > mode (they just flush one TLB at a time), not sure about xen. We could > actually go the other way and require that archs operate properly when > not in lazy mode (at least for kernel page tables) and avoid it for > apply_to_page_range()? Ryan Roberts hopefully brought some order to the topic: https://lore.kernel.org/linux-mm/20250303141542.3371656-1-ryan.roberts@arm.com/ > Thanks, > Nick