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 1414BD49C9E for ; Sat, 31 Jan 2026 17:29:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B5E406B0005; Sat, 31 Jan 2026 12:29:04 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AE1CC6B0088; Sat, 31 Jan 2026 12:29:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9EDB06B008A; Sat, 31 Jan 2026 12:29:04 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 8A67C6B0005 for ; Sat, 31 Jan 2026 12:29:04 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id E57471A037E for ; Sat, 31 Jan 2026 17:29:03 +0000 (UTC) X-FDA: 84392944566.02.CA5F7DE Received: from cvsmtppost105.wmail.worksmobile.com (cvsmtppost105.wmail.worksmobile.com [125.209.209.75]) by imf05.hostedemail.com (Postfix) with ESMTP id B4172100009 for ; Sat, 31 Jan 2026 17:29:00 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=worksmobile.com header.s=s20171120 header.b=t99Ppe5M; dkim=pass header.d=korea.ac.kr header.s=naverworks header.b=JIEzisgH; spf=pass (imf05.hostedemail.com: domain of ingyujang25@korea.ac.kr designates 125.209.209.75 as permitted sender) smtp.mailfrom=ingyujang25@korea.ac.kr; dmarc=pass (policy=none) header.from=korea.ac.kr ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1769880542; 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-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=YG4ly5XkBm7xH0RH1Wx27oM70Xf9pgUF0+jNK/Xq1W4=; b=NA9XUD+vqLKALLJryNwlFicVW0oYY4DjqmLJIH/kQLLxnbSL1h/1iQdCxNE0pwodJdNYM6 fUFb7W+yxdQO4OW+624kC6dpTWBhgVuT0dVR79WU5ejy+mHer7gP3gqxv3WDCHSrC3SFaP X8k/ju/4v7dh3LS0SwyPlHQgkzsAnX0= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1769880542; a=rsa-sha256; cv=none; b=e19+3FZ8QoD6qzTbbDJ7yujkNCQBrCNh+A/GyOVsLtW9zkV+kR6cAnqagrweGvyLo/UAae bUPzf0t0QH4c8LE7pLW8UBOYq2AXrsvW/LvJsudMou+rStyyeCZxbGyGQGKVAPyQO8QHUv bsMcAuxi5HyTS5A5u0xgZbkZZjfNiWg= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=worksmobile.com header.s=s20171120 header.b=t99Ppe5M; dkim=pass header.d=korea.ac.kr header.s=naverworks header.b=JIEzisgH; spf=pass (imf05.hostedemail.com: domain of ingyujang25@korea.ac.kr designates 125.209.209.75 as permitted sender) smtp.mailfrom=ingyujang25@korea.ac.kr; dmarc=pass (policy=none) header.from=korea.ac.kr DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=worksmobile.com; s=s20171120; t=1769880536; bh=xLdOzvJThZW5sBs7HVwMvfK8GTU5iAi2zlBS65q5Jrg=; h=From:To:Subject:Date:Message-Id:From:Subject:Feedback-ID: X-Works-Security; b=t99Ppe5Mvj8Sdqs/7W79q3UMcRMhlMrZlidlHFUMWJYxa+hEs0e1DmBHoIdxOQ2Tn biCgYBpKbvfIvtvaJRBN/sen5CabeAeXz2e9N/yr3/ffNAxlg+qEaNHnJ1102WxeWn yoE8a9ju4fcDbuShN4/DvBwSwKFe/f0ruOIvyjsjSv6uaMjkz/y+Ko35qqZllbVKjC +2JpTsr6AOqYa3B8D0gcozKuEVuXiow/Wuxby0w6xQaOPV7VDF9aZxo0/F1GDgLOmx BmDiEOs2o6lSnP8lyxp01dU6PzWe5TT3UBuuKvU60IbR7ZoxAbGWjykjlIm4S1DDuy AmFynLp4cbTBg== X-Originating-IP: 163.152.163.130 Received: from cvsendbo004.wmail ([10.113.20.173]) by cvsmtppost105.wmail.worksmobile.com with ESMTP id DocsLqBlTVOoLPlysr7fZg for ; Sat, 31 Jan 2026 17:28:56 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=korea.ac.kr; s=naverworks; t=1769880536; bh=xLdOzvJThZW5sBs7HVwMvfK8GTU5iAi2zlBS65q5Jrg=; h=From:To:Subject:Date:Message-Id:From:Subject:Feedback-ID: X-Works-Security; b=JIEzisgHXU72ifYP4yf5mJWAkn4OdPaF3kd+vF6N8926ff2wc+moHS4ytFQwFWtdd IvF3VJ7tatDF4fsKdud9d8Rsx3rgDwIqbfDMMm5qdpRRD4HAXoZHl7tjQ+kssjYZml spccO314otHOzgrOLssP6+7YInPb0GdnoyqNAdGE= X-Session-ID: GogdYXx2SUC-hottws6UZg X-Originating-IP: 163.152.163.130 X-Works-Send-Opt: EenqjAJYjHm/FqM9FqJYFxMqFNwYjAg= X-Works-Smtp-Source: AqndaAvrFqJZ+HmrKqu/+6E= Received: from s2lab05.. ([163.152.163.130]) by jvnsmtp401.gwmail.worksmobile.com with ESMTP id GogdYXx2SUC-hottws6UZg for (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384); Sat, 31 Jan 2026 17:28:56 -0000 From: Ingyu Jang To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, david@kernel.org, Ingyu Jang Subject: [Question] Dead code in copy_pud_range() for copy_huge_pud() error check? Date: Sun, 1 Feb 2026 02:28:54 +0900 Message-Id: <20260131172854.3370590-1-ingyujang25@korea.ac.kr> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: B4172100009 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 4qcsnw4qxrd1booiaxfnbbiwyxsumrqk X-HE-Tag: 1769880540-520224 X-HE-Meta: U2FsdGVkX19HLv2gL30yr+iKZSKPLTPlBQIZ8+jXACMcUva2y8xe7tePVJDTT9tLss5KMFGkUXfC8qRBmyOCOTDxf9cqpt24oYC5vdvilTT09g9fyqVBezbUQ/ot85INS7ZBgMAYTTA1l/XnNxVgsTYcbfRmzBXZi+JGW2QmREhjjOV2kzYI7GEOLbZqtwfkv159IoeGPRo9ScB/fIaEc2LECgGdsWEJYrpxMYGjdFgUh/N/573M1I/GA3FELK6hGw7cs+mcJVqi+MmYne0gux/PgHPhqq16E/i7IOytw+i+rus3fpvFWQsxhywPwDjG8wEGOUH66hsTrsaT1VpZpZFgg3aQKvkLMxY2ueKaQ5y+gmx1dn3ThDQ48wk/vrhEN6yI/PHGCGgNnKyW3KQlSZfl0TT7vBSNLkQMmCBjw0HBF3gCsYii9xNQo8Ob9Xwk8z5HDIWP3oBgJl2gzU3Q1+8FQ2yi4YoqLuk+Nbm8r/mPFbtrjbTphWqwmRWAzkoG+dtGvDIGtCGUezBGujMAtHwS/611d3aHwwRB/UlXOG9I9gtnYfky6zw+eWFcjyVGGLgzEqu38Igq5XUkk5C/Ljp4OaAAPC50uEg8hhwv1Z6Dp84cJklvXswcawRpUCDMhB9f6YZfQR0nuznPWlbi8kdfiW92jvWO2uNoxCilzugkBcjv5BOsCmiR7hzojD9Pe7+55swgL/VTVJ4q87vFQhaUQf6wUY3KK1n5oyLYAsIavAF3eY98IsFgOfDj8yKc8pEeXKzS848mVJhN76LKREEZ1w1rcBq+fiX0YwaBBuxIvLkIpWWEGwkBRr+R+DtkK+4XhhoeiNjuvsP6nd21m+r49FcGaMoO60qOvY1FIErR7iSY6xzeJ0PXl5W9Kj0Se6Tj2wKl/AjjzCpV0sBbzjAp3fZ0o3fCDm0w/7tRVf+t6MRcgfH6PxtxMqjiSZPhMz6KUlQRRNc57YspEZ/ Hyg4+rdr 9rBDqJWoWHUcE0UurFbc6ygXLCbAiUuJkdVXtHxTzqoO6CLKIm00D+ofn//p9C9IQ7l4Ean5jZk4pnLnKRNWp9aZ0fUlGkzOmb9BeqYRQvvAw4yq3fm3vTMxNk7eJXyxbALCGG+RGSZNSqRFYuHXuBvne6h8CE2UfUgrBA8nuxTFViQ0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.245724, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, I noticed that in mm/memory.c, the function copy_pud_range() checks if copy_huge_pud() returns -ENOMEM (at line 1421): err = copy_huge_pud(dst_mm, src_mm, dst_pud, src_pud, addr, src_vma); if (err == -ENOMEM) return -ENOMEM; However, looking at copy_huge_pud() in mm/huge_memory.c (line 1966), it only returns two values: - 0 on success (line 1994) - -EAGAIN when !pud_trans_huge(pud) (line 1978) There is no code path that returns -ENOMEM, which means the check "if (err == -ENOMEM)" at line 1421 is unreachable dead code. Is this intentional defensive coding for potential future changes, or could this unreachable error check be cleaned up? Thanks, Ingyu Jang