From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 553BB15AAC0; Thu, 18 Apr 2024 09:17:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713431879; cv=none; b=n2a67KqRxFzpY51iaI/NBhWbCXYWLyK/CNx8aNXuPPJxWIBZOICuiygOJdQF4dzEP0cwp9FYCWtIgROhIyPaPg1Hj8mleoPNX+LTZlIooB2bvAUzgAPXeLeOE+nKuipjce3NAoH64ufL+WadOymPiNneivxtgJIrFGy5RGIamTg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713431879; c=relaxed/simple; bh=YxaYhJG2YQxWNDuqETRxUhxSQmmg06Q1LDv1Ima5z6Y=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=dhi7tDEMn4qj6/3kpGtUPgw7WlQBIp509VwqazbCvCfMEM2qzkfZdPkStmJ/FHCVw9MCqs5cTrZQ+MST6EMTuQw9fMNgviskMwRQbsLZIvMy9fgWgiW+9r3kOipVYgtAi7qyaEC11wRu6qYgjrQfHz1SZox/20YTuDOmRZHUURU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=kYhmEVhy; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Pjd5L9qW; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="kYhmEVhy"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Pjd5L9qW" Date: Thu, 18 Apr 2024 11:17:53 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1713431876; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Oueb3ytqZ96zkn2QKrFrNWUZdLKfS4yQ3a5dkMeXex4=; b=kYhmEVhyg3DkkbnTYmIlxS/bFKU84wNu8BpFe4KuGjFRC45Ju9pdzyjfTIiEg9+oAknHqK chFRwQ33lTb9Hp9QE54aDK1i9iliWAq4BzCL6P3dVD2wtIn/b/Vezhmi2/S5JMp8Vtm/qf PwiUnqvezDYFBv5OAzF3OKQE1kN+JQUnqUkjfMmHCiB7VHEAAxL37u8txbRbfqLmOzUKsK JN67eqLCJTC8j3uBGTLQZ3SRw4MLkH5/FER5cSATmZu2Gbxs4THKcExo6fGUzO8a4fmtN8 tDiauRnpC0R2PkfZDLbrxdR1Aki8epCDaqVjKOuXqsaamIQUeONwF4BvKGDGBQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1713431876; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Oueb3ytqZ96zkn2QKrFrNWUZdLKfS4yQ3a5dkMeXex4=; b=Pjd5L9qWrP4A+6OlCBgjPk/bKfRDPSbEyBQGI8KS/tK/1yQbRHFlQx2CK1cL5UpXoDRFRc YqcsqTsBuFMHmWAQ== From: Nam Cao To: Andreas Dilger Cc: Mike Rapoport , Matthew Wilcox , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Christian Brauner , Al Viro , linux-fsdevel , Jan Kara , Linux Kernel Mailing List , linux-riscv@lists.infradead.org, Theodore Ts'o , Ext4 Developers List , Conor Dooley , Anders Roxell , Alexandre Ghiti Subject: Re: riscv32 EXT4 splat, 6.8 regression? Message-ID: <20240418111753.1c485974@namcao> In-Reply-To: <1F07FFF3-663B-43D4-A9DA-C89856F2962A@dilger.ca> References: <20240416-deppen-gasleitung-8098fcfd6bbd@brauner> <8734rlo9j7.fsf@all.your.base.are.belong.to.us> <20240416171713.7d76fe7d@namcao> <20240416173030.257f0807@namcao> <87v84h2tee.fsf@all.your.base.are.belong.to.us> <20240416181944.23af44ee@namcao> <20240417003639.13bfd801@namcao> <1F07FFF3-663B-43D4-A9DA-C89856F2962A@dilger.ca> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On 2024-04-17 Andreas Dilger wrote: > On Apr 16, 2024, at 4:36 PM, Nam Cao wrote: > > However, I am confused about one thing: doesn't this make one page of > > physical memory inaccessible? > > > > Is it better to solve this by setting max_low_pfn instead? Then at > > least the page is still accessible as high memory. > > Is that one page of memory really worthwhile to preserve? Better to > have a simple solution that works, Good point. > maybe even mapping that page > read-only so that any code which tries to dereference an ERR_PTR > address immediately gets a fault? Not sure about this part: it doesn't really fix the problem, just changes from subtle crashes into page faults. Let me send a patch to reserve the page: simple and works for all architectures. Best regards, Nam