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 C6BF4CCFA18 for ; Thu, 6 Nov 2025 03:42:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 478568E0009; Wed, 5 Nov 2025 22:42:04 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4293C8E0002; Wed, 5 Nov 2025 22:42:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2CAF58E0009; Wed, 5 Nov 2025 22:42:04 -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 1DE9F8E0002 for ; Wed, 5 Nov 2025 22:42:04 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id BCA6ABA0DF for ; Thu, 6 Nov 2025 03:42:03 +0000 (UTC) X-FDA: 84078783726.10.A858BD5 Received: from mail-ej1-f52.google.com (mail-ej1-f52.google.com [209.85.218.52]) by imf14.hostedemail.com (Postfix) with ESMTP id EC6B010000B for ; Thu, 6 Nov 2025 03:42:01 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=npQYKcEf; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf14.hostedemail.com: domain of richard.weiyang@gmail.com designates 209.85.218.52 as permitted sender) smtp.mailfrom=richard.weiyang@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1762400522; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references:dkim-signature; bh=4/mpB5etaPUKrc2ANXIhQoPHbxJ9dfZ4YjImlQ4KaKk=; b=uNpNsu+vjv4IpJ6GthLtoYOfig0pHj7HMPiH+QTv4p1bKxOc9JXrye15uMHTnqVFgq3RFo gEcOk7UQ0IiytpuN9FnIEs4q0sq1G3mApbueFf01mYdZysJBFy3UQze5uotfPCAlJoa0h/ lxK08G/2AwuXKQCTIujKweqHcBiEjwg= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1762400522; a=rsa-sha256; cv=none; b=emS9OTlCEnuyKlsE1w9Wv0wmo2RJ7MIVvdHKnyAS/etgAs6ay5cYWQ4Q1C4pY98GtSlKUc Ma4CeNx8bbLhjPCIXmDW+A2CoBe0cCkJNHE8FIXekfn6T8XqHaXtp4DFN7Q0HZiFfr4VaQ dtrcpK0tHkSbD9A6qf9I/E0E59i+4rY= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=npQYKcEf; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf14.hostedemail.com: domain of richard.weiyang@gmail.com designates 209.85.218.52 as permitted sender) smtp.mailfrom=richard.weiyang@gmail.com Received: by mail-ej1-f52.google.com with SMTP id a640c23a62f3a-b6d402422c2so105543866b.2 for ; Wed, 05 Nov 2025 19:42:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1762400520; x=1763005320; darn=kvack.org; h=references:in-reply-to:message-id:date:subject:cc:to:from:from:to :cc:subject:date:message-id:reply-to; bh=4/mpB5etaPUKrc2ANXIhQoPHbxJ9dfZ4YjImlQ4KaKk=; b=npQYKcEfrmC7Xcu9UxYTc5ynXrcdrxnbBeW3mZIgtL5CgkNmpvnMSybonaUtYnw0QV nCAx6fbRIrn1fjFmNzr0iF9E/VDfk1vGpdl2aossEHRiLpSHvjwKgCWcRJRGABNSg3TU F05hNjCFpHsGqVQFsp55fiXiRruYFAUqKxhamVtZZw8vvFr+hxXqLbbmM25x2uyT0+jD DE3R8ECpr5cbhaqw8jDB7+L3ayEsyNHp9r46gBqtMh+7S2ND/xTAF5rCyD5Nn8fx+BhI hHkLW0T9zK9zWSkFd+khN0zM5arbDNFlY2QHsff2gaB3ZxVJ5hRAXIrUOR+yNbzJNoYD 0+Ug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762400520; x=1763005320; h=references:in-reply-to:message-id:date:subject:cc:to:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=4/mpB5etaPUKrc2ANXIhQoPHbxJ9dfZ4YjImlQ4KaKk=; b=OsDXQzL4AGdfZi99JEyJYg3qLCm3RSgV0PVGSLNTLAuT/l6Zbt9brndlyk5nUUVox+ HpUwty7oRg14FR//+/UT71CTJD8OOBPRSKwx0t/TYq0MyZREncC8HGx4qWd8ySQ2u9zm Lym0bMPcwoc1s411DKRU/oZSFxNn60i7qwy+ipiFrRshWqaKkbvFLziUv8x2oaRlsWyv hz1sWD0XRKlKMbILUNNwzAl5day8qLazr4JsNfi3XroZjMgGYmtZaX50nwl1Zwdc5CnI deTCBALvLlEObwkYbvqm4oywo0BauKu9onwqZBpUO53+O81UPU82QSEBR1JOoLpSHqBY MQ1g== X-Gm-Message-State: AOJu0YwDdTekCDRATgEiWuIwpmH6Iuu0Ol00a09ldG4fieR0OHBw0zJu R5bP6nYJQyAx56GzIKL/Mg09is6t7pxtyhJXnhxkmDpZP5vGS09BShad X-Gm-Gg: ASbGncuPPprNWqLncfRNvXpapddIhnLF1+CQkdKxvh3t/f3rVHSzp0a+7jHMhqoJ5WH 54sAiu/S3VkIZyNOxWq/d+h9lVSk5xmRQPudSTZQOgvDatwOvHMlXmJ0/L8iRoWcDXu2z+jbwpw OxhPCJ6e4ojswpiIye54Isrfh7U3usUhl4A5ZLjH8ER0xVBqFbdy/4C5gnrv1tY50W5laQuqcw3 NnerVxnGQHvYloElMAnei6otT9AcVm+XkoIwIl4lItKRIAVu28Pn9NUCFbfZJGobEUonT67deEs arWuOEVC3Yuchos4RQxPRkYpsVntOFNT/LYoVuqutIlxK1bj/BXCV7/T2yNN4lsIwWF4qM/PXeb 9XKvHfplofNgO0bh56DHj8dKRgopK0+Ch5SYhwALa8dmhGbbF4X+bMJDfqSKfjxZYmF2kFC/OH5 XbPyCWg1d5Zw== X-Google-Smtp-Source: AGHT+IF5KA3uCNpvjjkiPMGerDFQxRaW6RARGz0uPcy9B1qLk0twVyWiEfDQvZ+2dd8P1+6EIVdbXQ== X-Received: by 2002:a17:906:c103:b0:b3a:ecc1:7774 with SMTP id a640c23a62f3a-b72655f0963mr620942766b.53.1762400520365; Wed, 05 Nov 2025 19:42:00 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b72893cc6c5sm108188666b.31.2025.11.05.19.41.59 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 05 Nov 2025 19:41:59 -0800 (PST) From: Wei Yang To: akpm@linux-foundation.org, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev Cc: linux-mm@kvack.org, Wei Yang Subject: [Patch v3 2/2] mm/huge_memory: merge uniform_split_supported() and non_uniform_split_supported() Date: Thu, 6 Nov 2025 03:41:55 +0000 Message-Id: <20251106034155.21398-3-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20251106034155.21398-1-richard.weiyang@gmail.com> References: <20251106034155.21398-1-richard.weiyang@gmail.com> X-Stat-Signature: jipzxsygumxh49ctxh9iqqd8439mtg1b X-Rspam-User: X-Rspamd-Queue-Id: EC6B010000B X-Rspamd-Server: rspam10 X-HE-Tag: 1762400521-263573 X-HE-Meta: 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 NxyVRYKf 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 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: The functions uniform_split_supported() and non_uniform_split_supported() share significantly similar logic. The only functional difference is that uniform_split_supported() includes an additional check on the requested @new_order. The reason for this check comes from the following two aspects: * some file system or swap cache just supports order-0 folio * the behavioral difference between uniform/non-uniform split The behavioral difference between uniform split and non-uniform: * uniform split splits folio directly to @new_order * non-uniform split creates after-split folios with orders from folio_order(folio) - 1 to new_order. This means for non-uniform split or !new_order split we should check the file system and swap cache respectively. This commit unifies the logic and merge the two functions into a single combined helper, removing redundant code and simplifying the split support checking mechanism. Signed-off-by: Wei Yang Cc: Zi Yan Cc: "David Hildenbrand (Red Hat)" --- v3: * adjust to use split_type * rebase on Zi Yan fix lkml.kernel.org/r/20251105162910.752266-1-ziy@nvidia.com v2: * remove need_check * update comment * add more explanation in change log --- include/linux/huge_mm.h | 8 ++--- mm/huge_memory.c | 71 +++++++++++++++++------------------------ 2 files changed, 33 insertions(+), 46 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 9e96dbe2f246..6f9e711b0954 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -374,10 +374,8 @@ int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list unsigned int new_order, bool unmapped); int min_order_for_split(struct folio *folio); int split_folio_to_list(struct folio *folio, struct list_head *list); -bool uniform_split_supported(struct folio *folio, unsigned int new_order, - bool warns); -bool non_uniform_split_supported(struct folio *folio, unsigned int new_order, - bool warns); +bool folio_split_supported(struct folio *folio, unsigned int new_order, + enum split_type split_type, bool warns); int folio_split(struct folio *folio, unsigned int new_order, struct page *page, struct list_head *list); @@ -408,7 +406,7 @@ static inline int split_huge_page_to_order(struct page *page, unsigned int new_o static inline int try_folio_split_to_order(struct folio *folio, struct page *page, unsigned int new_order) { - if (!non_uniform_split_supported(folio, new_order, /* warns= */ false)) + if (!folio_split_supported(folio, new_order, SPLIT_TYPE_NON_UNIFORM, /* warns= */ false)) return split_huge_page_to_order(&folio->page, new_order); return folio_split(folio, new_order, page, NULL); } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 659532199233..c676f2ab0611 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3686,8 +3686,8 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, return 0; } -bool non_uniform_split_supported(struct folio *folio, unsigned int new_order, - bool warns) +bool folio_split_supported(struct folio *folio, unsigned int new_order, + enum split_type split_type, bool warns) { if (folio_test_anon(folio)) { /* order-1 is not supported for anonymous THP. */ @@ -3695,48 +3695,41 @@ bool non_uniform_split_supported(struct folio *folio, unsigned int new_order, "Cannot split to order-1 folio"); if (new_order == 1) return false; - } else if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && - !mapping_large_folio_support(folio->mapping)) { - /* - * No split if the file system does not support large folio. - * Note that we might still have THPs in such mappings due to - * CONFIG_READ_ONLY_THP_FOR_FS. But in that case, the mapping - * does not actually support large folios properly. - */ - VM_WARN_ONCE(warns, - "Cannot split file folio to non-0 order"); - return false; - } - - /* Only swapping a whole PMD-mapped folio is supported */ - if (folio_test_swapcache(folio)) { - VM_WARN_ONCE(warns, - "Cannot split swapcache folio to non-0 order"); - return false; - } - - return true; -} - -/* See comments in non_uniform_split_supported() */ -bool uniform_split_supported(struct folio *folio, unsigned int new_order, - bool warns) -{ - if (folio_test_anon(folio)) { - VM_WARN_ONCE(warns && new_order == 1, - "Cannot split to order-1 folio"); - if (new_order == 1) - return false; - } else if (new_order) { + } else if (split_type == SPLIT_TYPE_NON_UNIFORM || new_order) { if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !mapping_large_folio_support(folio->mapping)) { + /* + * We can always split a folio down to a single page + * (new_order == 0) uniformly. + * + * For any other scenario + * a) uniform split targeting a large folio + * (new_order > 0) + * b) any non-uniform split + * we must confirm that the file system supports large + * folios. + * + * Note that we might still have THPs in such + * mappings, which is created from khugepaged when + * CONFIG_READ_ONLY_THP_FOR_FS is enabled. But in that + * case, the mapping does not actually support large + * folios properly. + */ VM_WARN_ONCE(warns, "Cannot split file folio to non-0 order"); return false; } } - if (new_order && folio_test_swapcache(folio)) { + /* + * swapcache folio could only be split to order 0 + * + * non-uniform split creates after-split folios with orders from + * folio_order(folio) - 1 to new_order, making it not suitable for any + * swapcache folio split. Only uniform split to order-0 can be used + * here. + */ + if ((split_type == SPLIT_TYPE_NON_UNIFORM || new_order) && folio_test_swapcache(folio)) { VM_WARN_ONCE(warns, "Cannot split swapcache folio to non-0 order"); return false; @@ -3794,11 +3787,7 @@ static int __folio_split(struct folio *folio, unsigned int new_order, if (new_order >= old_order) return -EINVAL; - if (split_type == SPLIT_TYPE_UNIFORM && !uniform_split_supported(folio, new_order, true)) - return -EINVAL; - - if (split_type == SPLIT_TYPE_NON_UNIFORM && - !non_uniform_split_supported(folio, new_order, true)) + if (!folio_split_supported(folio, new_order, split_type, /* warn = */ true)) return -EINVAL; is_hzp = is_huge_zero_folio(folio); -- 2.34.1