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 ECB01CF64AB for ; Thu, 20 Nov 2025 09:56:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3B06F6B00BB; Thu, 20 Nov 2025 04:56:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 387A16B00BC; Thu, 20 Nov 2025 04:56:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 29E106B00BE; Thu, 20 Nov 2025 04:56:10 -0500 (EST) 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 12DF56B00BB for ; Thu, 20 Nov 2025 04:56:10 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id C457FC07B9 for ; Thu, 20 Nov 2025 09:56:09 +0000 (UTC) X-FDA: 84130529658.10.E20395B Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf22.hostedemail.com (Postfix) with ESMTP id 945B7C0011 for ; Thu, 20 Nov 2025 09:56:07 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf22.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1763632568; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nJxhGPvS7Q5n6YTgfPNf48tD8CEv5gs8FHe0jGhiYtA=; b=WAirGf/1BdQRMCKu2udYSn3kU76flzXkjMVA7rR9k1oPBxA9zaNcAcaMj7cpQV/xf3H/74 CSPihojNvEBjKSTLYXEogC9Pu+50/gh1HSt0YjABwIutOaK3mOApTiGfxyIYEiZZZPmkGS duWqhF111vSXmS60lTOcwb6FOyo4vcY= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf22.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1763632568; a=rsa-sha256; cv=none; b=IUbp4hRgbFFYfLlGSPdc4SG5HBkIjkjt9r1ov+jz+ajFBNBI09kBCReO3dsX/jOqKz70dM IQ3uHNdF9YXftsNZ5RG+AElueduMRqpxuttrrqLF2BpOdgbYQewRZu3Be6RYdBq5+G2xsV Bh4UE34HZquA9hBrsaP6Nfc6H56TwYc= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C746A339; Thu, 20 Nov 2025 01:55:58 -0800 (PST) Received: from [10.164.18.59] (MacBook-Pro.blr.arm.com [10.164.18.59]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EE2F13F740; Thu, 20 Nov 2025 01:55:58 -0800 (PST) Message-ID: <7696ef91-89c0-427d-951b-56dbb33b4dd6@arm.com> Date: Thu, 20 Nov 2025 15:25:44 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2 2/2] mm/khugepaged: map dirty/writeback pages failures to EAGAIN To: "Garg, Shivank" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes Cc: Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Barry Song , Lance Yang , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Zach O'Keefe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org References: <20251120065043.41738-6-shivankg@amd.com> <20251120065043.41738-10-shivankg@amd.com> <6c1d6b80-d290-4110-9a49-53e7404136bc@arm.com> <33476cb4-318b-49db-9cc1-a354eca9e883@amd.com> Content-Language: en-US From: Dev Jain In-Reply-To: <33476cb4-318b-49db-9cc1-a354eca9e883@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 945B7C0011 X-Stat-Signature: w7iwdnggw49yqogmqz7i3tg3o41i55jr X-Rspam-User: X-HE-Tag: 1763632567-800391 X-HE-Meta: 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 5ZIoNeeR vHgv1BzCryzWpbJqJon/PKcraLVTLzwIC6DHrfXh7P1ibEuEno3jEQIO167eOKs+wXhHFEvmZ2A6hdv47BFdqAsW+s5oACckMR81sVgblsT8ADgCgP/iRa40vEolpm8p6uoWNWzrhGI5RuhSVLOAfhgDqzECOqwVaNwK/mDFxcZExgcTlyOEs82U/c6ASO1qqP8xofUne+xwawmVdIOGcblk5K/oSd7rqnQGu 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 20/11/25 1:47 pm, Garg, Shivank wrote: > > On 11/20/2025 1:33 PM, Dev Jain wrote: >> On 20/11/25 12:20 pm, Shivank Garg wrote: >> SCAN_PAGE_NOT_CLEAN is confusing - NOT_CLEAN literally means dirty, so why not SCAN_PAGE_DIRTY? >> Or SCAN_PAGE_DIRTY_OR_UNDER_WRITEBACK? Since folio_test_writeback() is true as a result of >> the folio being dirty, maybe just SCAN_PAGE_DIRTY can do. >> >> Reviewed-by: Dev Jain >> > Thanks for the review. > > I chose not to use SCAN_PAGE_DIRTY because dirty and writeback have different meanings[1]: > > Dirty: Memory that is waiting to be written back to disk > Writeback: Memory that is actively being written back to disk > > [1] https://www.kernel.org/doc/Documentation/filesystems/proc.txt > > IIUC, a page under writeback is no longer dirty, so using SCAN_PAGE_DIRTY would be misleading > for pages in the writeback state. > > I considered SCAN_PAGE_DIRTY_OR_WRITEBACK initially but felt it was too long. > > SCAN_PAGE_NOT_CLEAN covers both states that indicate the page is not in a clean/stable > state suitable for collapse. > > [1] https://www.kernel.org/doc/Documentation/filesystems/proc.txt Alright, makes sense. > > Thanks, > Shivank