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 8E5B2D73E83 for ; Thu, 29 Jan 2026 18:55:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B8FA46B0088; Thu, 29 Jan 2026 13:55:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B3D9C6B0089; Thu, 29 Jan 2026 13:55:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A49436B008A; Thu, 29 Jan 2026 13:55:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 8FF326B0088 for ; Thu, 29 Jan 2026 13:55:24 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 4807556FFA for ; Thu, 29 Jan 2026 18:55:24 +0000 (UTC) X-FDA: 84385904568.14.765C34F Received: from out-181.mta0.migadu.com (out-181.mta0.migadu.com [91.218.175.181]) by imf08.hostedemail.com (Postfix) with ESMTP id 6DE4C160004 for ; Thu, 29 Jan 2026 18:55:22 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ep3PjCt6; spf=pass (imf08.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.181 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1769712922; 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=9dbFuRTaIYbJLep7CcjvLi/9Eze7IQbnKopNMEF6Mkc=; b=LZyvLSlzrj/6+VaxA+LfVTZYaTlc8f/m7Ne+t3uSC1+yHOz/XAE/f2uiDKH1I/JOd0ti6q m29fyGjd1LQS5eWYEK9QjvBrfUAliCgR1OmDhmlOCUjnAItIoK6C16CN9k/3sZgUu8A4TD 0X3abJh2B5DHoqMZekgB3unhnEXPUtQ= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ep3PjCt6; spf=pass (imf08.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.181 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1769712922; a=rsa-sha256; cv=none; b=ZrM5lmNDhdrkHl5gI7SiFdYKPO6rmD9gLVwhzEN2swyvm73InE81Y30y+a6s34pelDxjSx Ov1Cp1u25U5uQ9eBN0T3YYN5Twlzy8ZiBraxIfQptR9c4iFDBHWPdpDmu1dHorNRioklpQ DjVQdHNBM+GxWZf9bgEmXcXO7UD6jCw= Date: Thu, 29 Jan 2026 10:55:14 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1769712920; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9dbFuRTaIYbJLep7CcjvLi/9Eze7IQbnKopNMEF6Mkc=; b=ep3PjCt6tHF0G2BvZiSi9+KqefVTxDYuLYGFClkmmcCPMAWX1fwDB2xgdE/CsCIM/QeSaF i0c5+0vxFYFdcETp13cZbicrbzpGENLnoEXgrA3ePMfvb2LNwWpNiqAxRZFSmUonPFLO+o mCa2ELM+utaM7jdEwRZVzquQIOhbbx4= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Rik van Riel , Song Liu , Kiryl Shutsemau , Usama Arif , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Meta kernel team , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: khugepaged: fix NR_FILE_PAGES accounting in collapse_file() Message-ID: References: <20260129184054.910897-1-shakeel.butt@linux.dev> <20260129105015.0ed043764a4ad220334b7ae1@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260129105015.0ed043764a4ad220334b7ae1@linux-foundation.org> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6DE4C160004 X-Stat-Signature: dmegiq48dixfh3ceyru87qkbxm8zip8y X-Rspam-User: X-HE-Tag: 1769712922-318914 X-HE-Meta: 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 EHkMOSAT Nd/LUskjZ+GSf4FGdKhhZdyCsRKThPpR7zMM/2tst1uhDqmi9nXc6S80uefyTzogLdcDsXvgfTQ2ATj0YUWFVCOcvthSRKAcW2CY/v/M5W6l9baWwWWh+sVh28b8S1bgqGkG6AIXMOXYuo95AadAtgCRRCpqX6yQZqyZVlikhkJ+tbNzmMgfP0lV7GyINFT0FbSM9nYVeBa3fji+3/C/X/MFoFLxSLN5AHcIkYES5ZNlqYi/ley0kOaDbqwC4V0EutaiT 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 Thu, Jan 29, 2026 at 10:50:15AM -0800, Andrew Morton wrote: > On Thu, 29 Jan 2026 10:40:54 -0800 Shakeel Butt wrote: > > > In META's fleet, we are seeing high level cgroups with zero file memcg > > stat but their descendants have non-zero file stat. This should not be > > possible. On further inspection by looking at kernel data structures > > though drgn, it was revealed that the high level cgroups have negative > > file stat which was aggregated from their children. > > > > Another interesting point was that this specific issue start happening > > more often as we started deploying thp-always more widely which > > indicates some correlation between file memory and THPs and indeed it > > was found that file memcg stat accounting is buggy in the collapse code > > path from the start. > > So this has no known runtime effect apart from incorrect accounting? Yes just an accounting bug. > > > Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > > Should we cc:stable? I think so.