From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from va-1-113.ptr.blmpb.com (va-1-113.ptr.blmpb.com [209.127.230.113]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3434E3F4847 for ; Wed, 1 Jul 2026 09:07:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.127.230.113 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782896863; cv=none; b=CgysbXbAcpUW6oIcn0MKidDCgdv2k32/Zy5NlgD8dLziwThx7jDJmF6dvRoyQfJi7QVDOnoKRUiHej7mDDUwzOgTvXO0R4EuML2RifUBap33863oWYyOohYvaFMFzhy/586oXQqKC/Bf0/O0GnqeiZWQQRjBgCacBrUu5fxnZ5s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782896863; c=relaxed/simple; bh=h3RqMd2Y44FtZIEueegymqy7vUk3TbpCcGzsh8Ub7x4=; h=To:Cc:From:Subject:Message-Id:Mime-Version:References:Date: In-Reply-To:Content-Type; b=Q+zVPnXu+fPLOZTU7PYhewWJrDapx7rQfULOPhC6vF8J+xxLyCDnaRsJuh8DAEWQa3mrxjuewuDLbIcasqZuck9F63rhN48LjuhkRLdoz5J9uqkeZbVIEWKxo2migfuO+9hXkhVmYdA4PNM8kfL3ZXKZwRMIh8ex/7txwrtQK2o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=bytedance.com; spf=pass smtp.mailfrom=bytedance.com; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b=KF6lDpW+; arc=none smtp.client-ip=209.127.230.113 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=bytedance.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bytedance.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b="KF6lDpW+" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=2212171451; d=bytedance.com; t=1782896856; h=from:subject: mime-version:from:date:message-id:subject:to:cc:reply-to:content-type: mime-version:in-reply-to:message-id; bh=Sen/XJQ1mPaPSt/blhLYv62ie6B/okRloNouG8j+xt4=; b=KF6lDpW+Sg8BdS4PEQTEraQEmDUy5Bh5V6qjE4DxPtev9kowk3bjujG+MFBJLEYtKGmAq9 M+yj9EGBYmk7m+K/0W2eerhaOWdZSM6+LFLLoZwfPe6ZemaoxMZIwzvLWnKJiW9cku3dhr i4taifsmiGMgjKn7oyIPts+DkFxovVuZuceTO9vqMfEo5nByQSbxkgdyti4Eohe0MoNHi6 VLx2aCAfyILWKePjzIl819HoIFB7dcHtu23bC1rIsBtFz5XqhZJKDQtkv4fWXyNINgQbZA mFlet4iRHhqQKsx2hP3k0C3LNo9RhUwAdW79Q4Y7PF6vTdkqQnSz03BLrU6j2w== To: , , , , , , , , , Cc: , , , , , X-Original-From: Li Zhe Content-Transfer-Encoding: 7bit X-Mailer: git-send-email 2.45.2 X-Lms-Return-Path: From: "Li Zhe" Subject: [PATCH v5 2/8] mm: factor zone-device page init helpers out of __init_zone_device_page Message-Id: <20260701090553.62691-3-lizhe.67@bytedance.com> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260701090553.62691-1-lizhe.67@bytedance.com> Date: Wed, 1 Jul 2026 17:05:47 +0800 In-Reply-To: <20260701090553.62691-1-lizhe.67@bytedance.com> Content-Type: text/plain; charset=UTF-8 memmap_init_zone_device() currently mixes refcount policy and core ZONE_DEVICE page setup in a single helper. Factor the refcount-reset predicate into pagemap_resets_refcount(), move the common page initialization into __zone_device_page_init(), and wrap the existing slow path in zone_device_page_init_slow(). This keeps the slow-path behaviour unchanged and gives later patches reusable helper boundaries. No functional change intended. Signed-off-by: Li Zhe Reviewed-by: Mike Rapoport (Microsoft) --- mm/mm_init.c | 57 ++++++++++++++++++++++++++++++++++------------------ 1 file changed, 38 insertions(+), 19 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 95808ab5cfdb..4c7fad440c2a 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1005,11 +1005,38 @@ static void __init memmap_init(void) } #ifdef CONFIG_ZONE_DEVICE -static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, +/* + * Return true when the free path for this pagemap type restores the page + * refcount to 1, so memmap_init_zone_device() can keep the count set by + * __init_single_page(). Otherwise initialize the refcount to 0 and leave + * it to the allocator or pgmap callbacks to raise it when the page is + * handed out again. + */ +static inline bool pagemap_resets_refcount(const struct dev_pagemap *pgmap) +{ + /* + * MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in the free + * path. The remaining ZONE_DEVICE types start from 0 here and raise + * the count again when the allocator or driver hands the page out. + */ + switch (pgmap->type) { + case MEMORY_DEVICE_FS_DAX: + case MEMORY_DEVICE_PRIVATE: + case MEMORY_DEVICE_COHERENT: + case MEMORY_DEVICE_PCI_P2PDMA: + return false; + case MEMORY_DEVICE_GENERIC: + return true; + default: + WARN_ONCE(1, "Unknown memory type!"); + return true; + } +} + +static void __ref __zone_device_page_init(struct page *page, unsigned long pfn, unsigned long zone_idx, int nid, struct dev_pagemap *pgmap) { - __init_single_page(page, pfn, zone_idx, nid); /* @@ -1028,23 +1055,15 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, */ page_folio(page)->pgmap = pgmap; page->zone_device_data = NULL; +} - /* - * MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in the free - * path. The remaining ZONE_DEVICE types start from 0 here and raise - * the count again when the allocator or driver hands the page out. - */ - switch (pgmap->type) { - case MEMORY_DEVICE_FS_DAX: - case MEMORY_DEVICE_PRIVATE: - case MEMORY_DEVICE_COHERENT: - case MEMORY_DEVICE_PCI_P2PDMA: +static void __ref zone_device_page_init_slow(struct page *page, + unsigned long pfn, unsigned long zone_idx, int nid, + struct dev_pagemap *pgmap) +{ + __zone_device_page_init(page, pfn, zone_idx, nid, pgmap); + if (!pagemap_resets_refcount(pgmap)) set_page_count(page, 0); - break; - - case MEMORY_DEVICE_GENERIC: - break; - } } /* @@ -1090,7 +1109,7 @@ static void __ref memmap_init_compound(struct page *head, for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) { struct page *page = pfn_to_page(pfn); - __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); + zone_device_page_init_slow(page, pfn, zone_idx, nid, pgmap); prep_compound_tail(page, head, order); set_page_count(page, 0); } @@ -1126,7 +1145,7 @@ void __ref memmap_init_zone_device(struct zone *zone, for (pfn = start_pfn; pfn < end_pfn; pfn += pfns_per_compound) { struct page *page = pfn_to_page(pfn); - __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); + zone_device_page_init_slow(page, pfn, zone_idx, nid, pgmap); if (IS_ALIGNED(pfn, PAGES_PER_SECTION)) cond_resched(); -- 2.20.1