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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D540C25B06 for ; Thu, 11 Aug 2022 21:17:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235862AbiHKVR6 (ORCPT ); Thu, 11 Aug 2022 17:17:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235882AbiHKVRy (ORCPT ); Thu, 11 Aug 2022 17:17:54 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D57269AFF3 for ; Thu, 11 Aug 2022 14:17:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 94A16B822A0 for ; Thu, 11 Aug 2022 21:17:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4331AC433C1; Thu, 11 Aug 2022 21:17:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1660252670; bh=nch9wki/g/+TYr2uO9esrhIzIw1eJS456Rlf3aRvNbY=; h=Date:To:From:Subject:From; b=0FWj4w92VsfDTLyvD7JQ+8izT1tqr5wfEv9zRJUJum3YZ2hF4ISReNBa6fzZbkSSt dU88paDqW8YHx6ddQ2ECCciyeEjokDb8rguNns1Z6d9id27K3YYQQ4JwplfCJ79965 TxsTCh9+wt91IfHMp7tIi1p/ZqN5ZMphJoDMQiYc= Date: Thu, 11 Aug 2022 14:17:49 -0700 To: mm-commits@vger.kernel.org, ying.huang@intel.com, vbabka@suse.cz, nadav.amit@gmail.com, minchan@kernel.org, kirill@shutemov.name, hughd@google.com, david@redhat.com, apopple@nvidia.com, andi.kleen@intel.com, aarcange@redhat.com, peterx@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-swap-cache-maximum-swapfile-size-when-init-swap.patch added to mm-unstable branch Message-Id: <20220811211750.4331AC433C1@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/swap: cache maximum swapfile size when init swap has been added to the -mm mm-unstable branch. Its filename is mm-swap-cache-maximum-swapfile-size-when-init-swap.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-cache-maximum-swapfile-size-when-init-swap.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Peter Xu Subject: mm/swap: cache maximum swapfile size when init swap Date: Thu, 11 Aug 2022 12:13:30 -0400 We used to have swapfile_maximum_size() fetching a maximum value of swapfile size per-arch. As the caller of max_swapfile_size() grows, this patch introduce a variable "swapfile_maximum_size" and cache the value of old max_swapfile_size(), so that we don't need to calculate the value every time. Caching the value in swapfile_init() is safe because when reaching the phase we should have initialized all the relevant information. Here the major arch to take care of is x86, which defines the max swapfile size based on L1TF mitigation. Here both X86_BUG_L1TF or l1tf_mitigation should have been setup properly when reaching swapfile_init(). As a reference, the code path looks like this for x86: - start_kernel - setup_arch - early_cpu_init - early_identify_cpu --> setup X86_BUG_L1TF - parse_early_param - l1tf_cmdline --> set l1tf_mitigation - check_bugs - l1tf_select_mitigation --> set l1tf_mitigation - arch_call_rest_init - rest_init - kernel_init - kernel_init_freeable - do_basic_setup - do_initcalls --> calls swapfile_init() (initcall level 4) The swapfile size only depends on swp pte format on non-x86 archs, so caching it is safe too. Since at it, rename max_swapfile_size() to arch_max_swapfile_size() because arch can define its own function, so it's more straightforward to have "arch_" as its prefix. At the meantime, export swapfile_maximum_size to replace the old usages of max_swapfile_size(). Link: https://lkml.kernel.org/r/20220811161331.37055-7-peterx@redhat.com Signed-off-by: Peter Xu Cc: Alistair Popple Cc: Andi Kleen Cc: Andrea Arcangeli Cc: David Hildenbrand Cc: Huang Ying Cc: Hugh Dickins Cc: "Kirill A . Shutemov" Cc: Minchan Kim Cc: Nadav Amit Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- arch/x86/mm/init.c | 2 +- include/linux/swapfile.h | 3 ++- include/linux/swapops.h | 2 +- mm/swapfile.c | 7 +++++-- 4 files changed, 9 insertions(+), 5 deletions(-) --- a/arch/x86/mm/init.c~mm-swap-cache-maximum-swapfile-size-when-init-swap +++ a/arch/x86/mm/init.c @@ -1054,7 +1054,7 @@ void update_cache_mode_entry(unsigned en } #ifdef CONFIG_SWAP -unsigned long max_swapfile_size(void) +unsigned long arch_max_swapfile_size(void) { unsigned long pages; --- a/include/linux/swapfile.h~mm-swap-cache-maximum-swapfile-size-when-init-swap +++ a/include/linux/swapfile.h @@ -8,6 +8,7 @@ */ extern struct swap_info_struct *swap_info[]; extern unsigned long generic_max_swapfile_size(void); -extern unsigned long max_swapfile_size(void); +/* Maximum swapfile size supported for the arch (not inclusive). */ +extern unsigned long swapfile_maximum_size; #endif /* _LINUX_SWAPFILE_H */ --- a/include/linux/swapops.h~mm-swap-cache-maximum-swapfile-size-when-init-swap +++ a/include/linux/swapops.h @@ -307,7 +307,7 @@ static inline bool migration_entry_suppo * the offset large enough to cover all of them (PFN, A & D bits). */ #ifdef CONFIG_SWAP - return max_swapfile_size() >= (1UL << SWP_MIG_TOTAL_BITS); + return swapfile_maximum_size >= (1UL << SWP_MIG_TOTAL_BITS); #else /* CONFIG_SWAP */ return false; #endif /* CONFIG_SWAP */ --- a/mm/swapfile.c~mm-swap-cache-maximum-swapfile-size-when-init-swap +++ a/mm/swapfile.c @@ -63,6 +63,7 @@ EXPORT_SYMBOL_GPL(nr_swap_pages); /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ long total_swap_pages; static int least_priority = -1; +unsigned long swapfile_maximum_size; static const char Bad_file[] = "Bad swap file entry "; static const char Unused_file[] = "Unused swap file entry "; @@ -2816,7 +2817,7 @@ unsigned long generic_max_swapfile_size( } /* Can be overridden by an architecture for additional checks. */ -__weak unsigned long max_swapfile_size(void) +__weak unsigned long arch_max_swapfile_size(void) { return generic_max_swapfile_size(); } @@ -2856,7 +2857,7 @@ static unsigned long read_swap_header(st p->cluster_next = 1; p->cluster_nr = 0; - maxpages = max_swapfile_size(); + maxpages = swapfile_maximum_size; last_page = swap_header->info.last_page; if (!last_page) { pr_warn("Empty swap-file\n"); @@ -3677,6 +3678,8 @@ static int __init swapfile_init(void) for_each_node(nid) plist_head_init(&swap_avail_heads[nid]); + swapfile_maximum_size = arch_max_swapfile_size(); + return 0; } subsys_initcall(swapfile_init); _ Patches currently in -mm which might be from peterx@redhat.com are mm-smaps-dont-access-young-dirty-bit-if-pte-unpresent.patch mm-uffd-reset-write-protection-when-unregister-with-wp-mode.patch mm-x86-use-swp_type_bits-in-3-level-swap-macros.patch mm-swap-comment-all-the-ifdef-in-swapopsh.patch mm-swap-add-swp_offset_pfn-to-fetch-pfn-from-swap-entry.patch mm-thp-carry-over-dirty-bit-when-thp-splits-on-pmd.patch mm-remember-young-dirty-bit-for-page-migrations.patch mm-swap-cache-maximum-swapfile-size-when-init-swap.patch mm-swap-cache-swap-migration-a-d-bits-support.patch