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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 10116CA5FA2 for ; Mon, 28 Sep 2026 10:06:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 26EC16B0092; Mon, 28 Sep 2026 06:06:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2442D6B0093; Mon, 28 Sep 2026 06:06:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 135696B0095; Mon, 28 Sep 2026 06:06:40 -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 B14086B0092 for ; Mon, 28 Sep 2026 06:06:39 -0400 (EDT) Received: from smtpin05.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 0B976A0173 for ; Mon, 28 Sep 2026 10:06:39 +0000 (UTC) X-FDA: 85262741718.05.068501F Received: from fhigh-a7-smtp.messagingengine.com (fhigh-a7-smtp.messagingengine.com [103.168.172.158]) by imf19.hostedemail.com (Postfix) with ESMTP id 149871A0007 for ; Mon, 28 Sep 2026 10:06:36 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=shutemov.name header.s=fm3 header.b="T /LZi2s"; dkim=pass header.d=messagingengine.com header.s=fm1 header.b="J/jYptmh"; dmarc=none; spf=pass (imf19.hostedemail.com: domain of kirill@shutemov.name designates 103.168.172.158 as permitted sender) smtp.mailfrom=kirill@shutemov.name ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790589997; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kcUsOL3101xiV9NL11+6UCDVa/c8zCTvs2ZvNLpRaUs=; b=WFvW8grlg3kGNeo9g4L+5klpVlNNYFlc9445hvaoeWGk4BwxPUsLMzerjBVg4f9aTJE1Nr W3zWgBLlgZM6DftSZQ4Fasrlb4t/b87lG7hO+e2Ag5koQpL3cOSo3GZILwtU7Fs0lEjnkh V/+mF23SiXgHwLQJ158iXK0bkCzeJKQ= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=shutemov.name header.s=fm3 header.b="T /LZi2s"; dkim=pass header.d=messagingengine.com header.s=fm1 header.b="J/jYptmh"; dmarc=none; spf=pass (imf19.hostedemail.com: domain of kirill@shutemov.name designates 103.168.172.158 as permitted sender) smtp.mailfrom=kirill@shutemov.name ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790589997; b=fuKnr+8MQfg9nhsl+hXd4gm3FlhkDOV2sbinRgP05HxZMEgoYdLDhiyXqlWRBgPDR9iz1c F9eM5Hru/2EC1zqBEIyrZEMPRd8TuR9qFLOm2I2VWCqgNziyTAAwnSpvhD0vU2q2DshU5+ +F/X1uzWV+ohrtgiTXliTxs069UKPEo= Received: from phl-compute-03.internal (phl-compute-03.internal [10.202.2.43]) by mailfhigh.phl.internal (Postfix) with ESMTP id 8823B14000DE; Mon, 28 Sep 2026 06:06:36 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-03.internal (MEProxy); Mon, 28 Sep 2026 06:06:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov.name; h=cc:cc:content-transfer-encoding:content-type:date:date:from :from:in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:subject:subject:to:to; s=fm3; t=1790589996; x= 1790676396; bh=kcUsOL3101xiV9NL11+6UCDVa/c8zCTvs2ZvNLpRaUs=; b=T /LZi2sg4uuBWkOjTyNhCVObsn/DS+ZLuyww5KBI+VR+LMoYmLG5qVxFC8DPJEMLU zCg5ZSDx3XZnBf3o6tAnnlv9XjbZ27plLqBnQQ4Mf9bf/RTnwlOyTlirAwLicNJH ePapL++6HhWEQYA6ODwWZ2qunWJXbRbqe9q1h4pnYckOItqJGJRcnEtxUNp1KCwW ng3U62MKI0mjf9QOVsQ6ScOnc9E5V2qKhfZUFNmWG4t1FqvXrs3rpeLNEsl3mPdx uhLSsX8vzlC6jH19/lOWaiB4CwHgI6a5andWwG1p5iLbKLnwaKa8GqyNjcD8BpWJ C8TSvDDX/Y1tNE8OksbEw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:subject:subject:to:to:x-me-proxy:x-me-sender :x-me-sender:x-sasl-enc; s=fm1; t=1790589996; x=1790676396; bh=k cUsOL3101xiV9NL11+6UCDVa/c8zCTvs2ZvNLpRaUs=; b=J/jYptmhWRqiG/+5q n4x+RmHp8dmJolILwLSCJFzPxbbLZHmFZVtponmj5hc8UQTP0VLUkdU9pxIRDLNF xQS6u/I+0mw5hl6/sojXitXHjxVRzuv/DZzEHaWj7SxIeze+7dQGpX5Xv5VwLKic C/usFjS4+GJXlZwkmwwvjJZM14uYEzJZxcBnl8ZF86OURQ5vtPhXPQ05PilZMhMb I/jPBg/iMbNdn3o1dDrD9DpQqYiZRah4p0dIO/a9dTseCpjAr2JO7ARtUgslG52k nkIA9oMCp2c6yY14BBU89d8y6nZhiZF+LUGovG5H6hrRHgFe3tKBLaV96AupCDxA EvRQQ== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTF8+FzWl2kPFFw+2+MUnNndpG3Es29zlM3W8MqBD0QW9993JqL27RjsdWHL5iQTuv 8LHkef+10EFcRNyu6aMfBJblGtUMhigK1wvWUg5pa/T2F4HZOycwBRl+2S+z7tqw2cJfHU gdsF/P6BOMqpKS9LZRm0d8oBtyKEEqCXwj8zji6pXjSixGW9yMDmevXCSXRhMug+RBOuj6 H/TPGEbj0UBxBpkklI8Q2dk1KPN1FfxQ05T6kAzB+fcPQyWzSSafNh6004OlOqdREfhbRG BHI+j7BDMASDclZuapGmxVrXolh8JlQnm8Hn+THchpsYHB/1yAmWKg/yew9Ltzw86nEqaa nkU2cSQL8qRENKHB4iLNlXxdqgyOVujeFZPY74aW8lk80wFKRFo5VNSaZ7AT7QmlDWD9LR 0yipAeB93S3lT7SuNh0By8tlp0OfFp2H8zgTSrQFo0KHX5n2NESmCyvNsDjZk8XaZbHIST ZPBWSoO1tX2inUBxZBeekbSe37r41xaOOV2PulMgtKG58RnGeLhAV0T8OH5yiRIoqbrmVd rE1verYunpxGQv9dp7hI2EwK8yDFx2fJJ/dWIgZxWZ5d1F2VtlbOGwI8/VX8tKwzmSYfE8 kXoTXNVhISb8KqFylRnZAVVbp+5Vyeo83tcqBZaBffEQeZold3dtspwRSUrw X-ME-Proxy: Feedback-ID: ie3994620:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 28 Sep 2026 06:06:35 -0400 (EDT) From: Kiryl Shutsemau To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang Cc: "Kiryl Shutsemau (Meta)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Jann Horn Subject: [PATCH v4 01/13] mm/khugepaged: drop redundant mm_struct pin in madvise_collapse() Date: Mon, 28 Sep 2026 11:06:15 +0100 Message-ID: <20260928100630.21870-2-kirill@shutemov.name> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260928100630.21870-1-kirill@shutemov.name> References: <20260928100630.21870-1-kirill@shutemov.name> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 96um9smgau4s9e4b8xq6s57gmmofg6b9 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 149871A0007 X-HE-Tag: 1790589996-862754 X-HE-Meta: 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 ZDBbMBNX 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Kiryl Shutsemau (Meta)" madvise_collapse() holds an mmgrab() reference across its work. It is redundant. Every caller already holds mm_users: - madvise(2) works on current->mm, which lives as long as the task is in the syscall; - process_madvise(2) reaches a remote mm through mm_access(), which takes an mm_users reference and holds it until the syscall returns; - io_uring passes current->mm; - DAMON takes one with get_task_mm() and drops it after the call. Drop the mmgrab()/mmdrop() pair. Assisted-by: LLM Acked-by: David Hildenbrand (Arm) Reviewed-by: Zi Yan Reviewed-by: Baolin Wang Signed-off-by: Kiryl Shutsemau (Meta) --- mm/khugepaged.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index e13d233b9967..75c876acf527 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -3229,7 +3229,6 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, cc->is_khugepaged = false; cc->progress = 0; - mmgrab(mm); lru_add_drain_all(); for (addr = hstart; addr < hend; addr += HPAGE_PMD_SIZE) { @@ -3285,7 +3284,6 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, } out_nolock: mmap_assert_locked(mm); - mmdrop(mm); kfree(cc); return thps == ((hend - hstart) >> HPAGE_PMD_SHIFT) ? 0 -- 2.54.0