From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-34.mta0.migadu.com [91.218.175.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F34553D16F0 for ; Thu, 15 Oct 2026 04:34:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792038855; cv=none; b=mPFKrsDLP/duZoULvusEWB5+90FUhqpJkhX4EuFbVFXkDRz4qAF4+Gu6c+ZoRphXD4GTPy3N07VhSyfgVyRdZNVr9N1HjZdTmt+xx58iur55n2x7BglaHBh3ETL+nvB2JgxpaTu4UElqdZYkXZuwwCKuiPOFJoULl8OV9406b4s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792038855; c=relaxed/simple; bh=tyD77QsF1TpQDhIMjdBhY/MqpYw4DT/Qu2z80DaAtcI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TyZHwFR2NGkyVb7xf32pJsv45SsHODVxkQQA/CwjL1AXdSjOf/+fcu2iNk19r9+7O5bpKm1KBso+Thc0/bL3ysYY03wnU99pg6S3ZH1qjukawtSi7QijB+jNQOZUFMpIprKVSsr4/x3ex2bYmK76qwaIlsIGMLKSDWe6nDuio04= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=dhsEw5MK; arc=none smtp.client-ip=91.218.175.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="dhsEw5MK" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=tyD77QsF1TpQDhIMjdBhY/MqpYw4DT/Qu2z80DaAtcI=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792038850; v=1; x=1792643650; b=dhsEw5MKBBoGzTz2w+QQH1VHDCAyl4zXmQkATTHI09MQO24gtw3YEC2O5JR/3Z85P5ul1FUU H/KNCWTprdhB/RgHdWFZ1ul/Da31iu5WJNnNlh9NOxBkrjErN4CuSZB3UP/iU5tQqS1U+L7G8v1 9IBheFIT97GPLhkjcIVWP8lg= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id b288e4c6ce06f05c; Thu, 15 Oct 2026 04:34:10 +0000 X-Mizu-Trace-ID: b288e4c6ce06f05c X-Migadu-Flow: FLOW_OUT From: Lance Yang To: kas@kernel.org Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, vbabka@kernel.org, jannh@google.com Subject: Re: [PATCH v5 1/9] mm/khugepaged: drop redundant mm_struct pin in madvise_collapse() Date: Thu, 15 Oct 2026 12:34:04 +0800 Message-ID: <20261015043404.57470-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261014171145.3292736-2-kas@kernel.org> References: <20261014171145.3292736-2-kas@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Wed, Oct 14, 2026 at 06:11:34PM +0100, Kiryl Shutsemau (Meta) wrote: >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) >--- Reviewed-by: Lance Yang