From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 E47B417BA2 for ; Thu, 26 Mar 2026 05:50:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774504241; cv=none; b=FTFDMMJaHVPfojWByznjkAmPxMm9dx5KKKqYjN3Ivsskc650jKQ9n3wNiQW+n+oTg3qbvEW8xDmLoImeccntMsw1sjGQ8cJn1u63GsokWSzRrwThXRG5zFuiKEiZgAJWQvSI8K96d75Y9n7BiHIJkVaSTc0J5CxnhtUkCxUdxQA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774504241; c=relaxed/simple; bh=bCuKlm3VeKiLaUNXvNVTWcyvcuR3kiNNLGQKB6jFkJA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iVOXuY6SLdmIgii3lpGpx93q50MBpa4uyNzoLfBgBHbZyOICIuglDXsDXOQv8r/8DJ3v4hPp+a8qIjie3zvjKeTRTelA3BuEGnEdW1de2U0rDubGI+dKC+tijVbuEolTmLaavItevQgQwUkB5f/IAjVt+AWWlsDdZHzAZH0iQjI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=jESuCKXI; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jESuCKXI" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=vCYIMgw31hZoV2qq5ERN/QG4vp4AeM8BHPz7QOX0MIE=; b=jESuCKXIRU6xrbGqN1bg5HqDQF Yg5KSrNdxFdu+X4fDizUM7Tax4NAtCqgpjaa5PdGsIhHfQsanwnAt0OxMbZC6ygGk0CTcSYAI2dgH gGYLslMyzOaPXI7L3Y+AF1/hREquoQYcs+Eo9XqfqLP8HQ8ToLDe2ceK4KI/Ml57+Q6UG4lkc5HJa zwqeORvDraz9EdQEPrvzJmhyGpsvJZiEPXSiGmR2H9ZBdyNycLWKwMvgFCWKO42GZRbjcv3vWJTqA UM4x39vSdZQr0DFls4F/kJyvSc/2EuzUXoQKZc4JQbKA3KD+XrEgLNbrzQqMNEAfwkt7TT3UmVPUR k0igtWXw==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5dc4-00000004lF2-07Px; Thu, 26 Mar 2026 05:50:36 +0000 Date: Wed, 25 Mar 2026 22:50:36 -0700 From: Christoph Hellwig To: Joanne Koong Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, jack@suse.cz, willy@infradead.org, miklos@szeredi.hu, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v1] mm: fix writeback regression for strictlimit BDIs Message-ID: References: <20260326001337.828947-1-joannelkoong@gmail.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: <20260326001337.828947-1-joannelkoong@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, Mar 25, 2026 at 05:13:37PM -0700, Joanne Koong wrote: > Commit 64dd89ae01f2 ("mm/block/fs: remove laptop_mode") removed this > unconditional writeback kick from balance_dirty_pages(): > > if (unlikely(!writeback_in_progress(wb))) > wb_start_background_writeback(wb); Yes, that looks like a bug. > This fixes the issue by kicking off the flusher if wb_dirty exceeds > wb_bg_thresh for strictlimit BDIs. This restores performance back to its > original baseline. What speaks against just reinstating the old-code as-is minus the misleading latop_mode comment?