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 E941CCA0FEE for ; Fri, 1 Sep 2023 16:46:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 54E298D0024; Fri, 1 Sep 2023 12:46:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D74E8D0002; Fri, 1 Sep 2023 12:46:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 378028D0024; Fri, 1 Sep 2023 12:46:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 2289F8D0002 for ; Fri, 1 Sep 2023 12:46:36 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id DEC761C94DC for ; Fri, 1 Sep 2023 16:46:35 +0000 (UTC) X-FDA: 81188607150.08.D4E0A6F Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) by imf11.hostedemail.com (Postfix) with ESMTP id 2ADAD40017 for ; Fri, 1 Sep 2023 16:46:33 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=xQdWt6jI; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf11.hostedemail.com: domain of 3aBXyZAsKCIknpxr4yrB60tt11tyr.p1zyv07A-zzx8npx.14t@flex--ackerleytng.bounces.google.com designates 209.85.214.202 as permitted sender) smtp.mailfrom=3aBXyZAsKCIknpxr4yrB60tt11tyr.p1zyv07A-zzx8npx.14t@flex--ackerleytng.bounces.google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693586794; 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:dkim-signature; bh=xCon5474F9WwphxhfgFhUzbwn0ALvK9xFv6P5Xz3AWM=; b=w8QtZk/s0L4Pt7zTayZAWL3p+0X4CQKKyDoPoLXtRO83MjYHuNdJuCb4mJECX+386/TxL2 L+h8vmkENPLU/SSRrDLb+tpOuF7IgMQ9B0BT3yaVj56yiXLX1pdYJ1ZLYvi3C3XiD7RPlz VriEPAtUJWPdjZ9/Y5Oki1xUT2BKnJs= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=xQdWt6jI; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf11.hostedemail.com: domain of 3aBXyZAsKCIknpxr4yrB60tt11tyr.p1zyv07A-zzx8npx.14t@flex--ackerleytng.bounces.google.com designates 209.85.214.202 as permitted sender) smtp.mailfrom=3aBXyZAsKCIknpxr4yrB60tt11tyr.p1zyv07A-zzx8npx.14t@flex--ackerleytng.bounces.google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693586794; a=rsa-sha256; cv=none; b=XxIaOiaJsUnxZut7jCO0Nwu/YtwPtzRV3iqBBvEW15tHR6Ly68o2nRuzCmurAEg1uxmLzY /42n+uGUco+DbgbacdwCJQUpcpW4H51tXTmrRasXmtzs0BVDfDagC05f7PwfIXnmTwrdQ7 oqf728P5K7fxqjMvjO09ejBzxXCeikM= Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-1c091a563ecso25333455ad.0 for ; Fri, 01 Sep 2023 09:46:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1693586793; x=1694191593; darn=kvack.org; h=cc:to:from:subject:message-id:mime-version:in-reply-to:date:from:to :cc:subject:date:message-id:reply-to; bh=xCon5474F9WwphxhfgFhUzbwn0ALvK9xFv6P5Xz3AWM=; b=xQdWt6jIwTrGK8VAOTfhHKNiXoj54l2OTj8qMGte/hOBJEEfXXTvEpJNKHvyuyT69J f39jnywy3KpPessA2Lpzx6VsJNQ+aYO480WnF+a9jtzgx2vgJwgSPn1T5GOUgudfi8Fv Yjm+S+WMCZ8T84SdkZv6zvCS/c8IXAY6LlXm2DxNZZZFgFJZb8psjFJB6+7/Wjvl6dsM 9WOw51Fq0q5Oi05RNBtQNGqrvcY5RCshwRi0kvQgm3wRPyhpxGUXqi2f5RaEZhxuFMIu e6U2VavfHEsNdK3dcvZFJei4toYpiM45UuzjvrSaFpcC2WqJbyqosjvphZq4dpLrk+jg R3wg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693586793; x=1694191593; h=cc:to:from:subject:message-id:mime-version:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=xCon5474F9WwphxhfgFhUzbwn0ALvK9xFv6P5Xz3AWM=; b=i8W0iqWJrq/qB1Z1u9sWK6SlBQUZJl8uPcrc1E4xSuecH3Q0UAvZLYwk2VZ1bEO6gY xciOi0cjlcGOgO6oHIwUbQdc7ewEbTgNE7tJTV7QdH8dbwCi4bBfqRCMS6MyfbQVjg16 3DtlKHPjr3g7Ym8FBwmDxjCWxWzkEOZMHIcW6Yxdrhxlq16Df94xtR1zKpf6jDDQFV0R 9VJDC0wejS1PCCFmJjh1y8wjRMCCVGIp3aHk5V9MrA5V2G7/tfTrNux7IyEULKBdkTO8 se+h/35jancYuvHxAHLZFKkcuqSk62SOznSDn/VyCvzFjU7GriEr4h/inPtyxibcH0o0 4Oaw== X-Gm-Message-State: AOJu0Yyd3695IdDKCCih08bzfs6sVbewuYZ9Q/S3svc/zWy3xt65sE1y 7+yteiIsaCfLkdtCpW+TKJLwuoHaOtAhUaLkvg== X-Google-Smtp-Source: AGHT+IE7IWuztjp33Ush39YmsLck94qkQHf2UcyeDE5trFHuf5V0W6HBwaqY0C7q2Vl17GPr3mAIvAb6tklgxvjU0g== X-Received: from ackerleytng-ctop.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:13f8]) (user=ackerleytng job=sendgmr) by 2002:a17:902:e887:b0:1bc:e6a:205e with SMTP id w7-20020a170902e88700b001bc0e6a205emr1066486plg.5.1693586792693; Fri, 01 Sep 2023 09:46:32 -0700 (PDT) Date: Fri, 01 Sep 2023 16:46:31 +0000 In-Reply-To: (message from Binbin Wu on Fri, 1 Sep 2023 11:45:43 +0800) Mime-Version: 1.0 Message-ID: Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory From: Ackerley Tng To: Binbin Wu Cc: kvm@vger.kernel.org, david@redhat.com, yu.c.zhang@linux.intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, chao.p.peng@linux.intel.com, linux-riscv@lists.infradead.org, isaku.yamahata@gmail.com, maz@kernel.org, paul@paul-moore.com, anup@brainfault.org, chenhuacai@kernel.org, jmorris@namei.org, willy@infradead.org, wei.w.wang@intel.com, tabba@google.com, jarkko@kernel.org, serge@hallyn.com, mail@maciej.szmigiero.name, aou@eecs.berkeley.edu, vbabka@suse.cz, michael.roth@amd.com, paul.walmsley@sifive.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, qperret@google.com, seanjc@google.com, liam.merwick@oracle.com, linux-mips@vger.kernel.org, oliver.upton@linux.dev, linux-security-module@vger.kernel.org, palmer@dabbelt.com, kvm-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, pbonzini@redhat.com, akpm@linux-foundation.org, vannapurve@google.com, linuxppc-dev@lists.ozlabs.org, kirill.shutemov@linux.intel.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2ADAD40017 X-Stat-Signature: wrj9wf7i3sj5oto53cdzw7zpmaijp3co X-Rspam-User: X-HE-Tag: 1693586793-804997 X-HE-Meta: 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 hEAYMlnn 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Binbin Wu writes: > > >> >> I'm not sure whose refcount the folio_put() in kvm_gmem_allocate() is >> dropping though: >> >> + The refcount for the filemap depends on whether this is a hugepage or >> not, but folio_put() strictly drops a refcount of 1. >> + The refcount for the lru list is just 1, but doesn't the page still >> remain in the lru list? > > I guess the refcount drop here is the one get on the fresh allocation. > Now the filemap has grabbed the folio, so the lifecycle of the folio now > is decided by the filemap/inode? > This makes sense! So folio_put() here is saying, I'm not using this folio anymore, but the filemap and the lru list are stil using the folio. >