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 A7FE8C7618E for ; Thu, 20 Apr 2023 21:27:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 120CF900003; Thu, 20 Apr 2023 17:27:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0AB0D900002; Thu, 20 Apr 2023 17:27:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E3E4A900003; Thu, 20 Apr 2023 17:27:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D461B900002 for ; Thu, 20 Apr 2023 17:27:01 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 941F5140448 for ; Thu, 20 Apr 2023 21:27:01 +0000 (UTC) X-FDA: 80703054642.06.63525DD Received: from wout2-smtp.messagingengine.com (wout2-smtp.messagingengine.com [64.147.123.25]) by imf25.hostedemail.com (Postfix) with ESMTP id 6DCE7A0029 for ; Thu, 20 Apr 2023 21:26:58 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=devkernel.io header.s=fm1 header.b=S48pqTi3; dkim=pass header.d=messagingengine.com header.s=fm3 header.b=ZSVGEgiu; spf=pass (imf25.hostedemail.com: domain of shr@devkernel.io designates 64.147.123.25 as permitted sender) smtp.mailfrom=shr@devkernel.io; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1682026019; 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=kypGF2ii73vq7/MLpGRQfGi3Vad0RUnvoKgRKQqP8c4=; b=KeUbaA+xThWUWcqLO4L7q+1vZVcmFAi64ciNYqU+mn3vxn79qGyPlGv28rZNjRyrkv7Qq0 ArhRktepBLVWEuQLWrNelQeg6/L0hEKgxL3+ivMgb4fzyBCwPwDXLxfv1ErqSq5xtYmp/u qfyxXYuifDtEn+2HB/dYr8A3SlwO5eA= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=devkernel.io header.s=fm1 header.b=S48pqTi3; dkim=pass header.d=messagingengine.com header.s=fm3 header.b=ZSVGEgiu; spf=pass (imf25.hostedemail.com: domain of shr@devkernel.io designates 64.147.123.25 as permitted sender) smtp.mailfrom=shr@devkernel.io; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1682026019; a=rsa-sha256; cv=none; b=p5liE0d1m++0yfMzP6nh/Ws3T6+JzgkrnCBRIrU0Che1Nk1OgM75ovj+BXvmaWIeZcyyk7 BG6bZrds7zlpuK3/CNdDGkYf4O+SVSAQtNcThIup77Ag9APFMrCPVcgt3jwSERq28qb/Lj JhP80rP5RYVHxtM0nB0z4mjCtsTqMsI= Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.west.internal (Postfix) with ESMTP id 88F83320024A; Thu, 20 Apr 2023 17:26:56 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Thu, 20 Apr 2023 17:26:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=devkernel.io; h= cc:cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm1; t=1682026016; x=1682112416; bh=ky pGF2ii73vq7/MLpGRQfGi3Vad0RUnvoKgRKQqP8c4=; b=S48pqTi3g1iCvy/lPY pwdM0OKwkxXwYg17Ey9YitSRRwLJaMco0E1lrPsaKNyVe6of1qlgN7I4WH42eTlz TxbmjMuZcdOBy3qDP9HkgJBk/Kk83EDd+iChTsbxrPGZthrkVWUOkEJkU0OA8YW6 OMBQqPFb1yChqi44/wV8kG1cYWSTX7f/pvv7KIfTDUUZYfv0uz0JAZ3DYCqxQWyA 7/m2hfq9uALNzk7/k5J51z/fbR0e/tFHwjv4zlUHdVKrIAhvTmx7QKcpL4PcE8vz b8Qeszm4CVrJDsQxBXCaJXJ9443SzGXyJaipIOYSv05S3pxLgOLL2k8zrZlGDVGg uBSQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; t=1682026016; x=1682112416; bh=kypGF2ii73vq7 /MLpGRQfGi3Vad0RUnvoKgRKQqP8c4=; b=ZSVGEgiumPxVBspocrub1eSMopJ8S i8lf1W0REVumFGfbjAzaGINMZ9CL+P8MN1MW4/x8eWtIPnqdexAedPqNlUqTERpJ 1TUNjSc+t52G0FBnez71PBFtu5ui03gcgFQXkALg3hm4yNJe23BggW4Xzx3LcV7p a0QFJuLfIXNbAzjuDkKmLV8WSebJZ9ZNGfGJDc4lEBPB96C05jwjKAe6sPvIx+kl 7dqxnrwIJb2veHWTH0DpJW0riSixxKiDI11p3QyYsBl1brQWBNcSGAxN1WyquFBw nfY8uboPHyVQFOXmZrXw3OqL0P7rWWtjjITUXiRCHo3cfchMT02Tb4eEw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrfedtvddgudeitdcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpehffgfhvfevufffjgfkgggtsehttdertddtredtnecuhfhrohhmpefuthgv fhgrnhcutfhovghstghhuceoshhhrhesuggvvhhkvghrnhgvlhdrihhoqeenucggtffrrg htthgvrhhnpeevlefggffhheduiedtheejveehtdfhtedvhfeludetvdegieekgeeggfdu geeutdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe hshhhrseguvghvkhgvrhhnvghlrdhioh X-ME-Proxy: Feedback-ID: i84614614:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 20 Apr 2023 17:26:53 -0400 (EDT) References: <20230418051342.1919757-1-shr@devkernel.io> <20230418152849.505124-1-david@redhat.com> <20230418152849.505124-2-david@redhat.com> User-agent: mu4e 1.10.1; emacs 28.2.50 From: Stefan Roesch To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Rik van Riel , Johannes Weiner , Michal Hocko , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Shuah Khan Subject: Re: [PATCH v1 1/3] mm/ksm: unmerge and clear VM_MERGEABLE when setting PR_SET_MEMORY_MERGE=0 Date: Thu, 20 Apr 2023 14:21:42 -0700 In-reply-to: <20230418152849.505124-2-david@redhat.com> Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: zefmkhp57pf5wi7n6x37hmuouerxi4w7 X-Rspamd-Queue-Id: 6DCE7A0029 X-HE-Tag: 1682026018-442679 X-HE-Meta: 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 J6ugbYFo 8XicXvwHBzB1LQpRz2ypvdy/w7mQQjYca1a6GkGI9gZoLSYnXjKAkF/HP+shtYUQVlkaYvokZ5hxkb1DBVDN4kI125P3W+HXA/gk7Poo5oHv14liv3TK2XBR3hbJ9CMHVoJuiN7DsHcA+j0RTOjbuTPNkvlhMSNtcoqueDY4+rqc7F0Gc0ciJiJnA6wabV1oov/0DY8GQ8i172E7Z+ZC3eeles+e2lOQE9PKqRN+BtkQvOoE= 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: David Hildenbrand writes: > Let's unmerge any KSM pages when setting PR_SET_MEMORY_MERGE=0, and clear > the VM_MERGEABLE flag from all VMAs -- just like KSM would. Of course, > only do that if we previously set PR_SET_MEMORY_MERGE=1. > > Signed-off-by: David Hildenbrand > --- > include/linux/ksm.h | 1 + > kernel/sys.c | 7 +------ > mm/ksm.c | 47 +++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 49 insertions(+), 6 deletions(-) > > diff --git a/include/linux/ksm.h b/include/linux/ksm.h > index 590934bdddcf..7108bc65dc2a 100644 > --- a/include/linux/ksm.h > +++ b/include/linux/ksm.h > @@ -21,6 +21,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, > > void ksm_add_vma(struct vm_area_struct *vma); > int ksm_enable_merge_any(struct mm_struct *mm); > +int ksm_disable_merge_any(struct mm_struct *mm); > > int __ksm_enter(struct mm_struct *mm); > void __ksm_exit(struct mm_struct *mm); > diff --git a/kernel/sys.c b/kernel/sys.c > index 72cdb16e2636..3436376667d7 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -2698,12 +2698,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, > if (arg2) { > error = ksm_enable_merge_any(me->mm); > } else { > - /* > - * TODO: we might want disable KSM on all VMAs and > - * trigger unsharing to completely disable KSM. > - */ > - clear_bit(MMF_VM_MERGE_ANY, &me->mm->flags); > - error = 0; > + error = ksm_disable_merge_any(me->mm); > } > nit: can we do: if (arg2) error = ksm_enable_merge_any(me->mm); else error = ksm_disable_merge_any(me->mm); mmap_write_unlock(me->mm); break; > diff --git a/mm/ksm.c b/mm/ksm.c > index a959e8925413..813f7fbc1832 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -2520,6 +2520,22 @@ static void __ksm_add_vma(struct vm_area_struct *vma) > vm_flags_set(vma, VM_MERGEABLE); > } > > +static int __ksm_del_vma(struct vm_area_struct *vma) > +{ > + int err; > + > + if (!(vma->vm_flags & VM_MERGEABLE)) > + return 0; > + > + if (vma->anon_vma) { > + err = unmerge_ksm_pages(vma, vma->vm_start, vma->vm_end); > + if (err) > + return err; > + } > + > + vm_flags_clear(vma, VM_MERGEABLE); > + return 0; > +} > /** > * ksm_add_vma - Mark vma as mergeable if compatible > * > @@ -2542,6 +2558,20 @@ static void ksm_add_vmas(struct mm_struct *mm) > __ksm_add_vma(vma); > } > > +static int ksm_del_vmas(struct mm_struct *mm) > +{ > + struct vm_area_struct *vma; > + int err; > + > + VMA_ITERATOR(vmi, mm, 0); > + for_each_vma(vmi, vma) { > + err = __ksm_del_vma(vma); > + if (err) > + return err; > + } > + return 0; > +} > + > /** > * ksm_enable_merge_any - Add mm to mm ksm list and enable merging on all > * compatible VMA's > @@ -2569,6 +2599,23 @@ int ksm_enable_merge_any(struct mm_struct *mm) > return 0; > } > > +int ksm_disable_merge_any(struct mm_struct *mm) > I understand we want to keep the name "symmetric" with ksm_enable_merge_any, but it also unmerges the ksm pages. Do we want to reflect that in the function name? Can we add a comment for the function? > +{ > + int err; > + > + if (!test_bit(MMF_VM_MERGE_ANY, &mm->flags)) > + return 0; > + > + err = ksm_del_vmas(mm); > + if (err) { > + ksm_add_vmas(mm); > + return err; > + } > + > + clear_bit(MMF_VM_MERGE_ANY, &mm->flags); > We only clear the MMF_VM_MERGE_ANY flag if there are no errors. Is this what we want? This means that if the process creates new memory regions they would still be marked as mergeable. > + return 0; > +} > + > int ksm_madvise(struct vm_area_struct *vma, unsigned long start, > unsigned long end, int advice, unsigned long *vm_flags) > {