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 C1917F5A8DA for ; Tue, 21 Apr 2026 03:45:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0C0A46B0088; Mon, 20 Apr 2026 23:45:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 072306B0089; Mon, 20 Apr 2026 23:45:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EA2466B008A; Mon, 20 Apr 2026 23:45:51 -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 DB95E6B0088 for ; Mon, 20 Apr 2026 23:45:51 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 6C0965C6DE for ; Tue, 21 Apr 2026 03:45:51 +0000 (UTC) X-FDA: 84681174102.07.CAEAF9F Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) by imf03.hostedemail.com (Postfix) with ESMTP id 23B8A20003 for ; Tue, 21 Apr 2026 03:45:48 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=FwnwfsJN; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=0g7slwHV; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=FwnwfsJN; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=0g7slwHV; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf03.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776743149; a=rsa-sha256; cv=none; b=gweqHLsik4hr0BVY33M5Lb/BHfYgFxtNt/DPunLO5AQWnGiDsZr4/oMtlCNlmz32sEdkqA /wu81W0r7rfD/x4Rj3rhlVqe/g7llM/5ytGM4MAIuhJW4pKZvkD3dLHZMMgtpdkF8ZTOCr 2QQz6zGNiLyzVDCDDAe5ILoLcVuOi+I= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=FwnwfsJN; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=0g7slwHV; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=FwnwfsJN; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=0g7slwHV; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf03.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776743149; 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=cJfTWXk1mSbZKfRW0DNvuHTmZm6Tw2gEEwGye/AIRbg=; b=6Lto2wu+ZkfpPPs8g8lUA04eB+/DaM57VoDSZpOrp7WM6xQnCrn4J5szJ6NF13IGbnZs2e umL1BhqCizA2pJSsWYiqqLAL76ZGUMIzWKRm1Vh5Renx7yGpiglm4mQynLy7k/HnuMos1d 5T89cwTLVEq2O7bXTXR+3Ne/F4digGw= Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 46DCF6A7EA; Tue, 21 Apr 2026 03:45:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1776743147; h=from:from:reply-to: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=cJfTWXk1mSbZKfRW0DNvuHTmZm6Tw2gEEwGye/AIRbg=; b=FwnwfsJNvJQyvE7l3cZfssEq4WjipWOchHPpCqYz8LwmH6Lmo4/24QiaMzyyBHixkRk2Oa MwuJTB0IcEOhwQzhpCCeVMOh9sNxCCEzpo4GLEbJ0KtsHSY19OyMkQDAofkMXzyNPLSRgK xGKCMsBZAoyXj6XV7ATB+ZIxX6pv6qM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1776743147; h=from:from:reply-to: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=cJfTWXk1mSbZKfRW0DNvuHTmZm6Tw2gEEwGye/AIRbg=; b=0g7slwHVd1GI62pXsPEDF4i5WYqsG2QxlBjPi3h2Aoz/fswC+9NDUJM0gq63WiR24nZtWp RNRv9RnJqNtv4xCw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1776743147; h=from:from:reply-to: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=cJfTWXk1mSbZKfRW0DNvuHTmZm6Tw2gEEwGye/AIRbg=; b=FwnwfsJNvJQyvE7l3cZfssEq4WjipWOchHPpCqYz8LwmH6Lmo4/24QiaMzyyBHixkRk2Oa MwuJTB0IcEOhwQzhpCCeVMOh9sNxCCEzpo4GLEbJ0KtsHSY19OyMkQDAofkMXzyNPLSRgK xGKCMsBZAoyXj6XV7ATB+ZIxX6pv6qM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1776743147; h=from:from:reply-to: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=cJfTWXk1mSbZKfRW0DNvuHTmZm6Tw2gEEwGye/AIRbg=; b=0g7slwHVd1GI62pXsPEDF4i5WYqsG2QxlBjPi3h2Aoz/fswC+9NDUJM0gq63WiR24nZtWp RNRv9RnJqNtv4xCw== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 58617593AF; Tue, 21 Apr 2026 03:45:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id U/DjEury5ml4VwAAD6G6ig (envelope-from ); Tue, 21 Apr 2026 03:45:46 +0000 Date: Tue, 21 Apr 2026 05:45:40 +0200 From: Oscar Salvador To: Muchun Song Cc: Andrew Morton , David Hildenbrand , Muchun Song , Michael Ellerman , Madhavan Srinivasan , Mike Rapoport , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nicholas Piggin , Christophe Leroy , aneesh.kumar@linux.ibm.com, joao.m.martins@oracle.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/4] mm/sparse-vmemmap: Fix vmemmap accounting underflow Message-ID: References: <20260421022044.1217503-1-songmuchun@bytedance.com> <20260421022044.1217503-2-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260421022044.1217503-2-songmuchun@bytedance.com> X-Rspamd-Server: rspam10 X-Stat-Signature: 6bqjd176ti6cctskb1rai1wiz74edc31 X-Rspam-User: X-Rspamd-Queue-Id: 23B8A20003 X-HE-Tag: 1776743148-242019 X-HE-Meta: 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 0zIWL+dM 0QBWK6YQhcXMRVco1ZZGqcamEOOLAqEIygW55S1pXbPXKomEfJLyj9guyQnGn9K7AjGqAcxifmEm1zvFKNUT1CgNuJT0WARGW0r5mbp09U0FVbDdO1cebTHP0JaVfuDbxdwbnJlTAPJVgcODXMtsIMLTXk1pJNjC8uwrq5dPxlBExkc/g70yzVuEWRhBNp2htVa3Pjqktj3IO4Ujy+6yJ57NwtpKIcu+slUFnjvwAbmG/v0M97sMqq1Orhtvtmx7u+D/UVj3Z2+V8jMpys+iizo8ykJXuQp2G5FlndHTYZbnr0963/+bfjRgzbA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Apr 21, 2026 at 10:20:41AM +0800, Muchun Song wrote: > In section_activate(), if populate_section_memmap() fails, the error > handling path calls section_deactivate() to roll back the state. This > causes a vmemmap accounting imbalance. > > Since commit c3576889d87b ("mm: fix accounting of memmap pages"), > memmap pages are accounted for only after populate_section_memmap() > succeeds. However, the failure path unconditionally calls > section_deactivate(), which decreases the vmemmap count. Consequently, > a failure in populate_section_memmap() leads to an accounting underflow, > incorrectly reducing the system's tracked vmemmap usage. > > Fix this more thoroughly by moving all accounting calls into the lower > level functions that actually perform the vmemmap allocation and freeing: > > - populate_section_memmap() accounts for newly allocated vmemmap pages > - depopulate_section_memmap() unaccounts when vmemmap is freed > > This ensures proper accounting in all code paths, including error > handling and early section cases. > > Fixes: c3576889d87b ("mm: fix accounting of memmap pages") > Signed-off-by: Muchun Song > Acked-by: Mike Rapoport (Microsoft) Acked-by: Oscar Salvador -- Oscar Salvador SUSE Labs