From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F33531A061; Thu, 16 Apr 2026 18:34:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776364483; cv=none; b=JGIF9hyBOBsilihMLZGhsnFNu2DAJ6iFz2PHOhwzCXoj5D4+YSPY6GK2jtsHfOUbvF4TcOf/b6j19BG3/4n7zz3eYEOneMhsIuJJAq7DzZg0MSXBBgRKJYpLcqaXUz3LIOT4EUMEocm8b7bTEUK4ax+ANlTFV6IIfK2U2qsn3kc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776364483; c=relaxed/simple; bh=tBiTiAmowFWBj69qdUg8eWQosB+vIOBxwoJdnWn8cw4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=sbjM0/YyU6KR6B3YXvQZhudsCGRYeFM59rn3evVOCIbcfZhXcjg1nyS2aI1WfIhzS1/DHxtpPiyiIlx5b8O8d+2BNBqUzBjYhOR1jjnU3hTvvH+Jvap2DwUvEyw9cpZO9dyshwGOK6g8uiTkY+LquDPFoCHjhwyjsLq9fMEDQYw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rvyo6VMc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rvyo6VMc" Received: by smtp.kernel.org (Postfix) with ESMTPS id 1D213C2BCB0; Thu, 16 Apr 2026 18:34:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776364483; bh=tBiTiAmowFWBj69qdUg8eWQosB+vIOBxwoJdnWn8cw4=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=rvyo6VMcLynWQVhZIqhF4UUHIv77LK+6plR8/GFBfcRFE1OY4l4NIF05aQ2h7bKQu hw6h3WXSZtXSlG95N1WyQlqZbhOJe+hY+PODvcCwM0sTcMIO1SS3VsN2JQhNx57dnl nI8kkUWgjpB1idrNMHjrzR2gCsSknor6hyVL099c/5y9v91SMRC2pGHtV/c2LSCcb3 tLa55UeR3We7kOQixitOe7xXsuh5ZXjJeHgZfpk/yMCWpLlN7e3D2b65sT5D4wzIbc DA7WAcI4HdaCOc6Peb03pgeihO4zhz6QeV/KsrTsy9Y5Q4X4zpU7xV4f0oEqRzDE84 EuZhQWP94wpqw== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D7D7F8D767; Thu, 16 Apr 2026 18:34:43 +0000 (UTC) From: Kairui Song via B4 Relay Date: Fri, 17 Apr 2026 02:34:32 +0800 Subject: [PATCH v2 02/11] mm, swap: move common swap cache operations into standalone helpers Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260417-swap-table-p4-v2-2-17f5d1015428@tencent.com> References: <20260417-swap-table-p4-v2-0-17f5d1015428@tencent.com> In-Reply-To: <20260417-swap-table-p4-v2-0-17f5d1015428@tencent.com> To: linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Zi Yan , Baolin Wang , Barry Song , Hugh Dickins , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Johannes Weiner , Youngjun Park , Chengming Zhou , Roman Gushchin , Shakeel Butt , Muchun Song , Qi Zheng , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Kairui Song , Yosry Ahmed , Lorenzo Stoakes , Dev Jain , Lance Yang , Michal Hocko , Michal Hocko , Qi Zheng , Lorenzo Stoakes , Yosry Ahmed X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1776364480; l=7606; i=kasong@tencent.com; s=kasong-sign-tencent; h=from:subject:message-id; bh=HpVIdXRr1EUECVgWZuJLDmJFOLfQVogQc6+DzLywiyw=; b=SwEVpOX11TdO0kzHMxfkZdsPnOyUE63uNUTZLtlSzzfSMRc/+13I/N8uDLQE+PY4+IaquBzxq A/ajo4XISw9DmVY/efzeO7IAHtQVi7zP6CHNlbdFweICKGMwEibj/LO X-Developer-Key: i=kasong@tencent.com; a=ed25519; pk=kCdoBuwrYph+KrkJnrr7Sm1pwwhGDdZKcKrqiK8Y1mI= X-Endpoint-Received: by B4 Relay for kasong@tencent.com/kasong-sign-tencent with auth_id=562 X-Original-From: Kairui Song Reply-To: kasong@tencent.com From: Kairui Song Move a few swap cache checking, adding, and deletion operations into standalone helpers to be used later. And while at it, add proper kernel doc. No feature or behavior change. Signed-off-by: Kairui Song --- mm/swap_state.c | 141 ++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 95 insertions(+), 46 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index eb4304aa00b7..3ef86db8220a 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -137,8 +137,42 @@ void *swap_cache_get_shadow(swp_entry_t entry) return NULL; } -void __swap_cache_add_folio(struct swap_cluster_info *ci, - struct folio *folio, swp_entry_t entry) +/** + * __swap_cache_add_check - Check if a range is suitable for adding a folio. + * @ci: The locked swap cluster. + * @ci_off: Range start offset. + * @nr: Number of slots to check. + * @shadow: Returns the shadow value if one exists in the range. + * + * Check if all slots covered by given range have a swap count >= 1. + * Retrieves the shadow if there is one. + * + * Context: Caller must lock the cluster. + */ +static int __swap_cache_add_check(struct swap_cluster_info *ci, + unsigned int ci_off, unsigned int nr, + void **shadow) +{ + unsigned int ci_end = ci_off + nr; + unsigned long old_tb; + + if (unlikely(!ci->table)) + return -ENOENT; + do { + old_tb = __swap_table_get(ci, ci_off); + if (unlikely(swp_tb_is_folio(old_tb))) + return -EEXIST; + if (unlikely(!__swp_tb_get_count(old_tb))) + return -ENOENT; + if (swp_tb_is_shadow(old_tb)) + *shadow = swp_tb_to_shadow(old_tb); + } while (++ci_off < ci_end); + + return 0; +} + +static void __swap_cache_do_add_folio(struct swap_cluster_info *ci, + struct folio *folio, swp_entry_t entry) { unsigned int ci_off = swp_cluster_offset(entry), ci_end; unsigned long nr_pages = folio_nr_pages(folio); @@ -159,7 +193,28 @@ void __swap_cache_add_folio(struct swap_cluster_info *ci, folio_ref_add(folio, nr_pages); folio_set_swapcache(folio); folio->swap = entry; +} +/** + * __swap_cache_add_folio - Add a folio to the swap cache and update stats. + * @ci: The locked swap cluster. + * @folio: The folio to be added. + * @entry: The swap entry corresponding to the folio. + * + * Unconditionally add a folio to the swap cache. The caller must ensure + * all slots are usable and have no conflicts. This assigns entry to + * @folio->swap, increases folio refcount by the number of pages, and + * updates swap cache stats. + * + * Context: Caller must ensure the folio is locked and lock the cluster + * that holds the entries. + */ +void __swap_cache_add_folio(struct swap_cluster_info *ci, + struct folio *folio, swp_entry_t entry) +{ + unsigned long nr_pages = folio_nr_pages(folio); + + __swap_cache_do_add_folio(ci, folio, entry); node_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages); lruvec_stat_mod_folio(folio, NR_SWAPCACHE, nr_pages); } @@ -168,9 +223,11 @@ void __swap_cache_add_folio(struct swap_cluster_info *ci, * swap_cache_add_folio - Add a folio into the swap cache. * @folio: The folio to be added. * @entry: The swap entry corresponding to the folio. - * @gfp: gfp_mask for XArray node allocation. * @shadowp: If a shadow is found, return the shadow. * + * Add a folio into the swap cache. Will return error if any slot is no + * longer a valid swapped out slot or already occupied by another folio. + * * Context: Caller must ensure @entry is valid and protect the swap device * with reference count or locks. */ @@ -179,60 +236,31 @@ static int swap_cache_add_folio(struct folio *folio, swp_entry_t entry, { int err; void *shadow = NULL; - unsigned long old_tb; + unsigned int ci_off; struct swap_info_struct *si; struct swap_cluster_info *ci; - unsigned int ci_start, ci_off, ci_end; unsigned long nr_pages = folio_nr_pages(folio); si = __swap_entry_to_info(entry); - ci_start = swp_cluster_offset(entry); - ci_end = ci_start + nr_pages; - ci_off = ci_start; ci = swap_cluster_lock(si, swp_offset(entry)); - if (unlikely(!ci->table)) { - err = -ENOENT; - goto failed; + ci_off = swp_cluster_offset(entry); + err = __swap_cache_add_check(ci, ci_off, nr_pages, &shadow); + if (err) { + swap_cluster_unlock(ci); + return err; } - do { - old_tb = __swap_table_get(ci, ci_off); - if (unlikely(swp_tb_is_folio(old_tb))) { - err = -EEXIST; - goto failed; - } - if (unlikely(!__swp_tb_get_count(old_tb))) { - err = -ENOENT; - goto failed; - } - if (swp_tb_is_shadow(old_tb)) - shadow = swp_tb_to_shadow(old_tb); - } while (++ci_off < ci_end); + __swap_cache_add_folio(ci, folio, entry); swap_cluster_unlock(ci); if (shadowp) *shadowp = shadow; - return 0; -failed: - swap_cluster_unlock(ci); - return err; + return 0; } -/** - * __swap_cache_del_folio - Removes a folio from the swap cache. - * @ci: The locked swap cluster. - * @folio: The folio. - * @entry: The first swap entry that the folio corresponds to. - * @shadow: shadow value to be filled in the swap cache. - * - * Removes a folio from the swap cache and fills a shadow in place. - * This won't put the folio's refcount. The caller has to do that. - * - * Context: Caller must ensure the folio is locked and in the swap cache - * using the index of @entry, and lock the cluster that holds the entries. - */ -void __swap_cache_del_folio(struct swap_cluster_info *ci, struct folio *folio, - swp_entry_t entry, void *shadow) +static void __swap_cache_do_del_folio(struct swap_cluster_info *ci, + struct folio *folio, + swp_entry_t entry, void *shadow) { int count; unsigned long old_tb; @@ -259,14 +287,12 @@ void __swap_cache_del_folio(struct swap_cluster_info *ci, struct folio *folio, folio_swapped = true; else need_free = true; - /* If shadow is NULL, we sets an empty shadow. */ + /* If shadow is NULL, we set an empty shadow. */ __swap_table_set(ci, ci_off, shadow_to_swp_tb(shadow, count)); } while (++ci_off < ci_end); folio->swap.val = 0; folio_clear_swapcache(folio); - node_stat_mod_folio(folio, NR_FILE_PAGES, -nr_pages); - lruvec_stat_mod_folio(folio, NR_SWAPCACHE, -nr_pages); if (!folio_swapped) { __swap_cluster_free_entries(si, ci, ci_start, nr_pages); @@ -279,6 +305,29 @@ void __swap_cache_del_folio(struct swap_cluster_info *ci, struct folio *folio, } } +/** + * __swap_cache_del_folio - Removes a folio from the swap cache. + * @ci: The locked swap cluster. + * @folio: The folio. + * @entry: The first swap entry that the folio corresponds to. + * @shadow: shadow value to be filled in the swap cache. + * + * Removes a folio from the swap cache and fills a shadow in place. + * This won't put the folio's refcount. The caller has to do that. + * + * Context: Caller must ensure the folio is locked and in the swap cache + * using the index of @entry, and lock the cluster that holds the entries. + */ +void __swap_cache_del_folio(struct swap_cluster_info *ci, struct folio *folio, + swp_entry_t entry, void *shadow) +{ + unsigned long nr_pages = folio_nr_pages(folio); + + __swap_cache_do_del_folio(ci, folio, entry, shadow); + node_stat_mod_folio(folio, NR_FILE_PAGES, -nr_pages); + lruvec_stat_mod_folio(folio, NR_SWAPCACHE, -nr_pages); +} + /** * swap_cache_del_folio - Removes a folio from the swap cache. * @folio: The folio. -- 2.53.0