From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 DF6C421101; Thu, 25 Apr 2024 20:10:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714075825; cv=none; b=m49LfSXMf21jDn3pDtltAq75epxCW3eq5ua2u+Y9D6gJFYDEl7amWfZIQTdzYuEbNi9hWABlECTEp8II4CZ172pF33UQBh8Mwsqw3wh1e75Vtutf+MAGAqUmtHZY9b9QycJBaqK5szpe/AVbA1DVXZgnAJqVYIcyVtYlfng5e58= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714075825; c=relaxed/simple; bh=dxbRTDBmGEBaFMzpv+zZKraLyNkVJK+Q3FXKOs5i1fU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EyYvlBxyd419KqNfvcrjsTjqf/OKgbsharWGI0TiknrEuBqAWsn9V5z/egTo2xJyA2Iw87gq+WZdTgVH8GFwOfgQfnGkIaTUkYCwFwFrMiJ0gIbV+Rxur1vrUuU/acckqCysncW9k8i1h5J3JwTQ88GHgykep20KaM+MIyYwarY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=cDuRE8Ic; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="cDuRE8Ic" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ut2lFHkwpmb+K3EVBzWHNHhXkqQsbBQiLvTVM0eN3X0=; b=cDuRE8IcWqDQDDIRZPUpK027nB xwfg9QuplaZFv+VpFFWIvtWT73JCqK/a1vhPkOIzHuMZ+X3hUT38iIn8NGjdTDbskzo3PQXcJo0nB EehnMcTq+mZrfAuV7jQybmKBkzGjPpO1wBFLZAjRJ+qgjdz+aV9W+2WYADSpf+APwM3HVzEDp17wx JmZf7Y2MLLlqPIbRMUw8RXfY/2KP/i4IwLFEibc9z9h4NIsxupSc5ZLNG1BpBMS7oZQxNNea8UUEo po85wU7raeUp1Dn5YinkeiZIYukVdn4vDpYDPR/vhwkBsDcgl3umYUQFhG/i4oA03nTt8G2FHEWy8 yUWvwvOg==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s05Q9-00000003hkb-01z4; Thu, 25 Apr 2024 20:10:17 +0000 Date: Thu, 25 Apr 2024 21:10:16 +0100 From: Matthew Wilcox To: "Pankaj Raghav (Samsung)" Cc: djwong@kernel.org, brauner@kernel.org, david@fromorbit.com, chandan.babu@oracle.com, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, hare@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, mcgrof@kernel.org, gost.dev@samsung.com, p.raghav@samsung.com Subject: Re: [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement Message-ID: References: <20240425113746.335530-1-kernel@pankajraghav.com> <20240425113746.335530-6-kernel@pankajraghav.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240425113746.335530-6-kernel@pankajraghav.com> On Thu, Apr 25, 2024 at 01:37:40PM +0200, Pankaj Raghav (Samsung) wrote: > From: Pankaj Raghav > > Splitting a larger folio with a base order is supported using > split_huge_page_to_list_to_order() API. However, using that API for LBS > is resulting in an NULL ptr dereference error in the writeback path [1]. > > Refuse to split a folio if it has minimum folio order requirement until > we can start using split_huge_page_to_list_to_order() API. Splitting the > folio can be added as a later optimization. > > [1] https://gist.github.com/mcgrof/d12f586ec6ebe32b2472b5d634c397df Obviously this has to be tracked down and fixed before this patchset can be merged ... I think I have some ideas. Let me look a bit. How would I go about reproducing this?