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 14E9A25F974 for ; Fri, 28 Feb 2025 16:36:07 +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=1740760569; cv=none; b=I5Nj24pW4ND3sw6M/p4bKohklXktCUH41wa4Tt+WR2f9qkYM0UCz+MRFnVgq+HuD8PFG3YY18V4VBxoPBses0pSjZpof9buDeDDew8DqD/BjFyxICUjlWaEWTutCZ9tjEN/O+PE2SQBvyeHfBryKf2541vcaXf98/ao2s4hc/HI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740760569; c=relaxed/simple; bh=K77CUEtfwG/93Vke5Pk7GR9JF/a9/uvCr7iYeET14t8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=q+52g049uHQ7J3toId5p08JDHqHlaSKhEe3jTsZTmdR9cQpaz1/cVYFjEzhdPIlMe2lmHhjYFbIznfMw4DQZiIetZr/FNb3R4GGgGA0azLsJn8ixWVBcKLxdReEPXW7GvbabF8vT7ZrJjiUmjxTijwfi19Yo+dPDlZpE0ad1/hk= 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=ovGoa2vf; 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="ovGoa2vf" 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=e9vSoM+7hs95bKdKIg7eM5WyD/pdP0vSTAfr15Di75g=; b=ovGoa2vfaZnp6Y6O28EKx54pAK Zj/UuoQrcat4WFUQ+tUC+KgWadHtP4ZC18yJPvdTuzTmlHPmcV+IIamHGRi35wZLrlmMxkHZgXiUq 0tGOjVRGcubtySli2aoHuDuZKHZF4WQwgp3hj2jGW64zkEUpRRsSzlRcwBtTpoXwdvtumS3/9nrt3 +jciZIOZboUV35URq/DRdKOR3DPSR7Q91iezreRzK/Xh0syqR/MyrgTbY/QhvmKRUYPNN36vjtXcs rCsYOwzZ4jHojdkQvda83BdHrIkPr7Ka5iiCKd7W8KBVRgpX8WeKKPY248Gq8vl5wB2p1GFd7p8aM T2+J+qGg==; Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1to3KR-000000033wq-1NiW; Fri, 28 Feb 2025 16:35:16 +0000 Date: Fri, 28 Feb 2025 16:35:11 +0000 From: Matthew Wilcox To: Zi Yan Cc: Liu Shixin , Baolin Wang , linux-mm@kvack.org, Andrew Morton , Barry Song , David Hildenbrand , Kefeng Wang , Lance Yang , Ryan Roberts , Hugh Dickins , Charan Teja Kalla , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/migrate: fix shmem xarray update during migration Message-ID: References: <20250228154219.2214149-1-ziy@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20250228154219.2214149-1-ziy@nvidia.com> On Fri, Feb 28, 2025 at 10:42:19AM -0500, Zi Yan wrote: > @@ -524,7 +525,11 @@ static int __folio_migrate_mapping(struct address_space *mapping, > folio_set_swapcache(newfolio); > newfolio->private = folio_get_private(folio); > } > - entries = nr; > + /* shmem uses high-order entry */ > + if (shmem_mapping(mapping)) It's be cheaper to check folio_test_anon() here, right? Also, how did this bug remain unnoticed for almost 4 years? Our testing is terrible ;-( > + entries = 1; > + else > + entries = nr; > } else { > VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio); > entries = 1; > -- > 2.47.2 >