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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1745182631; 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:dkim-signature; bh=gIkY4yeXUHf1NiZGEJzThxeparc024ntgho2Fz1MLYA=; b=M7OtlusI5W6OPIcDZuEfp0qv0qKIkL/vnuYLRp7yPn5wDC37UOHwl276nTP5VV+70pDHJF ZXKTsBkFxY5ZNMkDIEiQ+bHeImGG7TGg+cTc4gxGUEAGye5BiK5zY94TePsqNCqhSM8ERx of1xUDDGJ9k8YfSonxhP8UiqsxzUUdg= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id AB8F36112C; Sun, 20 Apr 2025 20:56:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D8773C4CEE2; Sun, 20 Apr 2025 20:57:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1745182630; bh=Sxde0RTvzDoz/23To40dR0fqqHqU/hEqFdENRbnQG1Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ohEfi8w8ep1dh50B/D20GFW2IFu+vcwFZuFiKG5WXFhLkCujp+I/FSMovGVW/uCBv uNY6X1RD1P5KfErxi0YBzZ3MRIe2LJpH0xcFcMgqXwDWBd1kag3+TEBNf3N4rMvHnc gJhYmaFHrOTOGYtHeHSElxa53r1Ek2MIeeBYiN4Q= Date: Sun, 20 Apr 2025 13:57:09 -0700 From: Andrew Morton To: Ruihan Li Cc: Mike Rapoport , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/mm_init: Don't iterate pages below ARCH_PFN_OFFSET Message-Id: <20250420135709.732883ee775ad8b41fb668ca@linux-foundation.org> In-Reply-To: <20250419122801.1752234-1-lrh2000@pku.edu.cn> References: <20250419122801.1752234-1-lrh2000@pku.edu.cn> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4CADC40004 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: 3wuond37gfr5z91t9ijfkq434pd55q5m X-HE-Tag: 1745182631-419156 X-HE-Meta: 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 Bgg== 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 Sat, 19 Apr 2025 20:28:01 +0800 Ruihan Li wrote: > If ARCH_PFN_OFFSET is very large (e.g., something like 2^64-2GiB if the > kernel is used as a library and loaded at a very high address), the > pointless iteration for pages below ARCH_PFN_OFFSET will take a very > long time, and the kernel will look stuck at boot time. > > This commit sets the initial value of pfn_hole to ARCH_PFN_OFFSET, which > avoids the problematic and useless iteration mentioned above. > > This problem has existed since commit 907ec5fca3dc ("mm: zero remaining > unavailable struct pages"). > > Signed-off-by: Ruihan Li > --- > Link to v1: > - https://lore.kernel.org/linux-mm/20250418162727.1535335-1-lrh2000@pku.edu.cn/ > Changes since v1: > - Removed the unnecessary Fixes tag. Why was the Fixes: considered unnecessary? It seems to be useful information?