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 417E8CA0FF9 for ; Fri, 29 Aug 2025 16:30:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8E8BC8E0007; Fri, 29 Aug 2025 12:30:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8C0508E0001; Fri, 29 Aug 2025 12:30:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7FD5D8E0007; Fri, 29 Aug 2025 12:30:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 6E3F38E0001 for ; Fri, 29 Aug 2025 12:30:30 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id D6F41140804 for ; Fri, 29 Aug 2025 16:30:29 +0000 (UTC) X-FDA: 83830332978.15.1BB0B04 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf06.hostedemail.com (Postfix) with ESMTP id 31D3B18001A for ; Fri, 29 Aug 2025 16:30:28 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=dfkJ0HGC ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1756485028; a=rsa-sha256; cv=none; b=Uc8UA5S5TWJsgxbe7Bxm/yYQpF2PyyG8g98NTEy7JVHfveum4s7ClKxA5ZKze5be4ZPijR lx66AyUwJl+Bidfocmrz63CbXEjKn+J//wKqAeWQ/hSig2ZuqTF/RVU9B1McUserJ5mi/o JJc831m3VxzxZOSK42Vuws0kxZyNAlk= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=dfkJ0HGC; dmarc=none; spf=none (imf06.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1756485028; 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:in-reply-to:references:references:dkim-signature; bh=6wufkbHjb9cVwLDFN2ioiC4hewzh6PkDpKG3aZ3Uujw=; b=G6fXiPe7lFXFsIUujL8mKttV5ggu3Gy+Y11TtAhhTYLhWNhGlIMlL1jDoKlgkMLdWlcfNc BL/a8xMm8JTdKS4o41/81zxFKF3/l4LMm1wYI69W/47AsapZi4GX/fpcRBlvBypn6IRbbI OYN4cjlaqfBc6rs2ZC/eIWO7S8Q1jL0= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=6wufkbHjb9cVwLDFN2ioiC4hewzh6PkDpKG3aZ3Uujw=; b=dfkJ0HGC2Le/sqbVa9mYTay1LC VikQi648gc/fuMqpKSUbHj0Xsmm0a2wkoTFWT3WrV4N0qSkG4hNErMm994tbL9+QjtvJ06knVrf9Q NvmF+iZjVmJidl9dbPVi0Bd0rU1Yd6a6nfVZ1UpLadLSLaW5Wno2QRNtYSB9I1ZYqR+yWQct+9DIZ aaeSCNAfWjFsdUkpCsHYlds/2O8ijdjey0Lwdq8NCnRDT+kMt9gVntWje9sVBFuQvqH1G3hUjZMMN Jjikg8HxajH6A/I75VhAleh8HrC8xD6M2VK1NoF/3PVI9JbbzHPZ/9Dy6G6rk1wlR83XWpwrd5pDq WpFb4hZA==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1us1K7-0000000EFwH-0z8M; Fri, 29 Aug 2025 15:47:31 +0000 From: "Matthew Wilcox (Oracle)" To: Vlastimil Babka , Andrew Morton Cc: "Matthew Wilcox (Oracle)" , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , linux-mm@kvack.org Subject: [PATCH 06/22] slab: Reimplement page_slab() Date: Fri, 29 Aug 2025 16:47:10 +0100 Message-ID: <20250829154728.3397606-7-willy@infradead.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250829154728.3397606-1-willy@infradead.org> References: <20250829154728.3397606-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 31D3B18001A X-Stat-Signature: chjwi56zb17oso3a57ggbuttpg7kzqj9 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1756485028-661245 X-HE-Meta: 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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: In order to separate slabs from folios, we need to convert from any page in a slab to the slab directly without going through a page to folio conversion first. page_slab() is a little different from other memdesc converters we have in that it will return NULL if the page is not part of a slab. This will be the normal style for memdesc converters in the future. kfence was the only user of page_slab(), so adjust it to the new way of working. It will need to be touched again when we separate slab from page. Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/page-flags.h | 14 +------------- mm/kfence/core.c | 12 ++++++++---- mm/slab.h | 28 ++++++++++++++++------------ 3 files changed, 25 insertions(+), 29 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 5ee6ffbdbf83..39ed2f243279 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -1052,19 +1052,7 @@ PAGE_TYPE_OPS(Table, table, pgtable) */ PAGE_TYPE_OPS(Guard, guard, guard) -FOLIO_TYPE_OPS(slab, slab) - -/** - * PageSlab - Determine if the page belongs to the slab allocator - * @page: The page to test. - * - * Context: Any context. - * Return: True for slab pages, false for any other kind of page. - */ -static inline bool PageSlab(const struct page *page) -{ - return folio_test_slab(page_folio(page)); -} +PAGE_TYPE_OPS(Slab, slab, slab) #ifdef CONFIG_HUGETLB_PAGE FOLIO_TYPE_OPS(hugetlb, hugetlb) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 0ed3be100963..5fb0f0f8f99a 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -613,12 +613,14 @@ static unsigned long kfence_init_pool(void) * enters __slab_free() slow-path. */ for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { - struct slab *slab = page_slab(nth_page(pages, i)); + struct page *page = nth_page(pages, i); + struct slab *slab; if (!i || (i % 2)) continue; - __folio_set_slab(slab_folio(slab)); + __SetPageSlab(page); + slab = page_slab(page); #ifdef CONFIG_MEMCG slab->obj_exts = (unsigned long)&kfence_metadata_init[i / 2 - 1].obj_exts | MEMCG_DATA_OBJEXTS; @@ -665,14 +667,16 @@ static unsigned long kfence_init_pool(void) reset_slab: for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { - struct slab *slab = page_slab(nth_page(pages, i)); + struct page *page = nth_page(pages, i); + struct slab *slab; if (!i || (i % 2)) continue; + slab = page_slab(page); #ifdef CONFIG_MEMCG slab->obj_exts = 0; #endif - __folio_clear_slab(slab_folio(slab)); + __ClearPageSlab(page); } return addr; diff --git a/mm/slab.h b/mm/slab.h index bf2f91a6c535..084231394250 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -142,20 +142,24 @@ static_assert(IS_ALIGNED(offsetof(struct slab, freelist), sizeof(freelist_aba_t) struct slab *: (struct folio *)s)) /** - * page_slab - Converts from first struct page to slab. - * @p: The first (either head of compound or single) page of slab. + * page_slab - Converts from struct page to its slab. + * @page: A page which may or may not belong to a slab. * - * A temporary wrapper to convert struct page to struct slab in situations where - * we know the page is the compound head, or single order-0 page. - * - * Long-term ideally everything would work with struct slab directly or go - * through folio to struct slab. - * - * Return: The slab which contains this page + * Return: The slab which contains this page or NULL if the page does + * not belong to a slab. This includes pages returned from large kmalloc. */ -#define page_slab(p) (_Generic((p), \ - const struct page *: (const struct slab *)(p), \ - struct page *: (struct slab *)(p))) +static inline struct slab *page_slab(const struct page *page) +{ + unsigned long head; + + head = READ_ONCE(page->compound_head); + if (head & 1) + page = (struct page *)(head - 1); + if (data_race(page->page_type >> 24) != PGTY_slab) + page = NULL; + + return (struct slab *)page; +} /** * slab_page - The first struct page allocated for a slab -- 2.47.2