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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48342C369A8 for ; Thu, 10 Apr 2025 13:08:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5867B6B02B2; Thu, 10 Apr 2025 09:08:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5366B6B02B3; Thu, 10 Apr 2025 09:08:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3FB596B02B4; Thu, 10 Apr 2025 09:08:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 20EB56B02B2 for ; Thu, 10 Apr 2025 09:08:39 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 0B51DC0A48 for ; Thu, 10 Apr 2025 13:08:39 +0000 (UTC) X-FDA: 83318163558.04.624BE37 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) by imf12.hostedemail.com (Postfix) with ESMTP id C114D40002 for ; Thu, 10 Apr 2025 13:08:36 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=ltdp53VW; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=NDnNRhO6; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=ltdp53VW; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=NDnNRhO6; spf=pass (imf12.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744290517; 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=JQ+GE9TVlMaXc0U/j9vFk5uI5XCKPbbp9Ak9w+zgA3g=; b=PpCkCQAYaz9WWB3ca6KBXKFcC0NE1dxB/n54Awmuxtou7BbumVgj0MWJ3KRUJUvxPBa0En W6XNoNh5n9tTmb+47Hc0saSGKcT6e4vp/BWhdEogq1UNZGrhr3CgqrDvCTtw7uvuPnN1Xb U/3FV9QQOecwquPcjy7XNPogguPM+gk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1744290517; a=rsa-sha256; cv=none; b=XiGKCtVockwuGmM8kaWM7EhRwz3pZ7Dor02Z2vDE8WvE9HdWyDxGRkYS79HL4E4K2cJfGc 1BVoLfQYjyjZBFbBnTez8yLUxpnqI95pWXBJm3aEtn9rxyjfT2hRp1p9FeHmmYYqNvntl/ T/L4g2D1JSihnK07iiJI5n2ji6wWjls= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=ltdp53VW; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=NDnNRhO6; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=ltdp53VW; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=NDnNRhO6; spf=pass (imf12.hostedemail.com: domain of osalvador@suse.de designates 195.135.223.130 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (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 152DE21166; Thu, 10 Apr 2025 13:08:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1744290515; 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=JQ+GE9TVlMaXc0U/j9vFk5uI5XCKPbbp9Ak9w+zgA3g=; b=ltdp53VWtTufTRvgtyHpInvkWOHVNfCdEJSJkoDc0uokyeq7zckk6u0acA0YcMta/h2dN3 1FS9+ww4Kvt2wCuRwOEQXZJCJxQGyxYOh+D2/9cgxXUHb2U62AvdWiMS+ulGuR6StIakuU XpsvUk9Ef595xroZIj/eGVzYr1si0jU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1744290515; 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=JQ+GE9TVlMaXc0U/j9vFk5uI5XCKPbbp9Ak9w+zgA3g=; b=NDnNRhO6/DlVDH1EQDP1rhKf40t017jcRX1jfIkEHAjGR3vWHD2pYhAQiiGIq8BMlSDxB9 qh1MCfj3aLVnZKAw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1744290515; 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=JQ+GE9TVlMaXc0U/j9vFk5uI5XCKPbbp9Ak9w+zgA3g=; b=ltdp53VWtTufTRvgtyHpInvkWOHVNfCdEJSJkoDc0uokyeq7zckk6u0acA0YcMta/h2dN3 1FS9+ww4Kvt2wCuRwOEQXZJCJxQGyxYOh+D2/9cgxXUHb2U62AvdWiMS+ulGuR6StIakuU XpsvUk9Ef595xroZIj/eGVzYr1si0jU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1744290515; 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=JQ+GE9TVlMaXc0U/j9vFk5uI5XCKPbbp9Ak9w+zgA3g=; b=NDnNRhO6/DlVDH1EQDP1rhKf40t017jcRX1jfIkEHAjGR3vWHD2pYhAQiiGIq8BMlSDxB9 qh1MCfj3aLVnZKAw== 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 6925513886; Thu, 10 Apr 2025 13:08:34 +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 cQhhFNLC92eRYQAAD6G6ig (envelope-from ); Thu, 10 Apr 2025 13:08:34 +0000 Date: Thu, 10 Apr 2025 15:08:32 +0200 From: Oscar Salvador To: Gavin Shan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, adityag@linux.ibm.com, donettom@linux.ibm.com, david@redhat.com, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, akpm@linux-foundation.org, shan.gavin@gmail.com Subject: Re: [PATCH] drivers/base/memory: Avoid overhead from for_each_present_section_nr() Message-ID: References: <20250410125110.1232329-1-gshan@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250410125110.1232329-1-gshan@redhat.com> X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: C114D40002 X-Stat-Signature: gzbbmf81onx1o45y6dn7rjmu988ni78c X-HE-Tag: 1744290516-301819 X-HE-Meta: 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 mmFdFz5T uKnoF86bjnYuNN6kx9/YCoNxOq32FKLOYCiYRO84Fefg035kdCZ+ZMPzVyVL8bkKE8eyHCIwxlf5i0vK1R0LxdvStOggukuUIz/i6Z1aMJrT4+6bfvLqnCbQSJajCTeBVd9lNw4cOWtm62LHItYvQv56ByzA5uDlqtZbGB1Jw7VLT1AhhVKwQo/gww2jj/GloyvIKFpGC1J5nii5du2h58Rv6EDjXiUlM3tjAozbio+voCnHTlVs7b5TLCNYRGr/b9TnL2joszz9in8KCyTR0nH4ucIpnZyJ1dbteOJyTFA7v3R3Z6VLeuWeLewIivNSyokCLTltOrlRvbbtVqp5lKlrppfynYeWtJ6aayw5VL1r2RIKLOTnKUQdDzW86UA6MvtfBpJEuXGBN3d9qOE7DT/z9hK8YNx23k33q 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, Apr 10, 2025 at 10:51:10PM +1000, Gavin Shan wrote: > for_each_present_section_nr() was introduced to add_boot_memory_block() > by commit 61659efdb35c ("drivers/base/memory: improve add_boot_memory_block()"). > It causes unnecessary overhead when the present sections are really > sparse. next_present_section_nr() called by the macro to find the next > present section, which is far away from the spanning sections in the > specified block. Too much time consumed by next_present_section_nr() > in this case, which can lead to softlockup as observed by Aditya Gupta > on IBM Power10 machine. > > watchdog: BUG: soft lockup - CPU#248 stuck for 22s! [swapper/248:1] > Modules linked in: > CPU: 248 UID: 0 PID: 1 Comm: swapper/248 Not tainted 6.15.0-rc1-next-20250408 #1 VOLUNTARY > Hardware name: 9105-22A POWER10 (raw) 0x800200 opal:v7.1-107-gfda75d121942 PowerNV > NIP: c00000000209218c LR: c000000002092204 CTR: 0000000000000000 > REGS: c00040000418fa30 TRAP: 0900 Not tainted (6.15.0-rc1-next-20250408) > MSR: 9000000002009033 CR: 28000428 XER: 00000000 > CFAR: 0000000000000000 IRQMASK: 0 > GPR00: c000000002092204 c00040000418fcd0 c000000001b08100 0000000000000040 > GPR04: 0000000000013e00 c000c03ffebabb00 0000000000c03fff c000400fff587f80 > GPR08: 0000000000000000 00000000001196f7 0000000000000000 0000000028000428 > GPR12: 0000000000000000 c000000002e80000 c00000000001007c 0000000000000000 > GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > GPR24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > GPR28: c000000002df7f70 0000000000013dc0 c0000000011dd898 0000000008000000 > NIP [c00000000209218c] memory_dev_init+0x114/0x1e0 > LR [c000000002092204] memory_dev_init+0x18c/0x1e0 > Call Trace: > [c00040000418fcd0] [c000000002092204] memory_dev_init+0x18c/0x1e0 (unreliable) > [c00040000418fd50] [c000000002091348] driver_init+0x78/0xa4 > [c00040000418fd70] [c0000000020063ac] kernel_init_freeable+0x22c/0x370 > [c00040000418fde0] [c0000000000100a8] kernel_init+0x34/0x25c > [c00040000418fe50] [c00000000000cd94] ret_from_kernel_user_thread+0x14/0x1c > > Avoid the overhead by folding for_each_present_section_nr() to the outer > loop. add_boot_memory_block() is dropped after that. > > Fixes: 61659efdb35c ("drivers/base/memory: improve add_boot_memory_block()") > Closes: https://lore.kernel.org/linux-mm/20250409180344.477916-1-adityag@linux.ibm.com > Reported-by: Aditya Gupta > Signed-off-by: Gavin Shan Acked-by: Oscar Salvador -- Oscar Salvador SUSE Labs