From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 41330EFB816 for ; Tue, 24 Feb 2026 08:46:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6A56A6B0088; Tue, 24 Feb 2026 03:46:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 652C86B0089; Tue, 24 Feb 2026 03:46:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5627D6B008A; Tue, 24 Feb 2026 03:46:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 42B4C6B0088 for ; Tue, 24 Feb 2026 03:46:17 -0500 (EST) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 01FE91BFF0 for ; Tue, 24 Feb 2026 08:46:16 +0000 (UTC) X-FDA: 84478718394.20.FF5E068 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) by imf26.hostedemail.com (Postfix) with ESMTP id 13E26140008 for ; Tue, 24 Feb 2026 08:46:14 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=t1zC1XfD; spf=pass (imf26.hostedemail.com: domain of lance.yang@linux.dev designates 95.215.58.174 as permitted sender) smtp.mailfrom=lance.yang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1771922775; a=rsa-sha256; cv=none; b=IusyWT8v5X9B25IRnAB3MRPIP+DcRQTjUOC4uMQ/N6u8FCTGZ9eryJRLGMoSjTKDb6Kh6v yBxof+1QqJt/ZyWhqxrAq68RTX70q9UacLb/M/UGf1w5cJGgbXJpnWD89fosMhCFMFnKNF 0E2BlXQVwsYjPm4XNXYn2N72/yQZQQo= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=t1zC1XfD; spf=pass (imf26.hostedemail.com: domain of lance.yang@linux.dev designates 95.215.58.174 as permitted sender) smtp.mailfrom=lance.yang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1771922775; 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=0uJ5WZpkoz2PlS+e/oWj8d2/Z4RKR5KjB8D2HwBT1fg=; b=uZ/lHBb7Cydi5gpsnbrUiom35K8X++bkhlP3ReI2yHb0xx+Twn6MZIXHJ7uvxuaLS7QhrV zkzcGJcPkB8TIyThHEA0Y7MwZHmr+B1TtXqYUwstgVrfz/1HdidxYAr27sqmFygLPwj73J RGxRw4P9DODL74RIkbMFtK5xr+BZxpk= Message-ID: <108e41e4-cbfb-458d-b72a-1becca61327d@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1771922772; 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=0uJ5WZpkoz2PlS+e/oWj8d2/Z4RKR5KjB8D2HwBT1fg=; b=t1zC1XfDHs3l9Q9JLpteHHfp9nCw9LADY1Q8lpmx29IDaZSudYzOpnNIiBSFgxI2EJ8Qwd S+Z5BbbMlxcvho7b56/rsvu3mcbvd/Jb12rbxrNkKGF/HT9REF8IoNOyUbuIMYwwbkEBYC qsYxYZJwWkWvBLRFYa8r5gJ3i+dUzCw= Date: Tue, 24 Feb 2026 16:45:59 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] khugepaged: convert redundant check to WARN_ON Content-Language: en-US To: Baolin Wang , Dev Jain Cc: ziy@nvidia.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, david@kernel.org, lorenzo.stoakes@oracle.com References: <20260219054827.4111334-1-dev.jain@arm.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 13E26140008 X-Stat-Signature: tq1uwnyjokgy5assb3g6du11mfire7nt X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1771922774-841633 X-HE-Meta: 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 rE5bXzzB E9C++HpcXMR8MmPri9oWmnna9npzPfJzdT2A7dbVdcwywUnfkqzLQEk6380ItNXE2nbdwGU/QIPxCZ1NO648CZ1Ch4Z7joyZQ73Igwp2MsEyqQemqi8cM2yq+H8xqau8Z9rr1bEYQ3uCu+1b3MvXJrlI9JqCuJaqZQzsqW4sTE2/+DMWQVafVzr4GEWmraqgNMm7ajSfAgAp8nQlDzDwPL05izz7phjLSJNnT0/MW6sIPIta9Nt3HCtjcr9DUAc7p32cIGPpRO/23Kv0AniDdkhwAgQlg3bwcf8Isg/j6UYQAhSzSYR5kkPUrXS9LOH0QksPaOdXEYSpHBbuRy2o7g/JzBw== 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 2026/2/24 16:21, Baolin Wang wrote: > > > On 2/19/26 1:48 PM, Dev Jain wrote: >> Claim: folio_order(folio) == HPAGE_PMD_ORDER => folio->index == start. >> >> Proof: Both loops in hpage_collapse_scan_file and collapse_file, which >> iterate on the xarray, have the invariant that >> start <= folio->index < start + HPAGE_PMD_NR ... (i) >> A folio is always naturally aligned in the pagecache, therefore >> folio_order == HPAGE_PMD_ORDER => IS_ALIGNED(folio->index, >> HPAGE_PMD_NR) == true ... (ii) >> thp_vma_allowable_order -> thp_vma_suitable_order requires that the >> virtual >> offsets in the VMA are aligned to the order, >> => IS_ALIGNED(start, HPAGE_PMD_NR) == true ... (iii) >> >> Combining (i), (ii) and (iii), the claim is proven. >> >> Therefore, convert this to a VM_WARN_ON. >> >> Signed-off-by: Dev Jain >> --- > > Make sense to me. Personally, I’d like to keep this VM_WARN_ON() to > catch unexpected behavior. +1 Reviewed-by: Lance Yang