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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 620E9C25B06 for ; Fri, 12 Aug 2022 02:34:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C60AE8E0005; Thu, 11 Aug 2022 22:34:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C10668E0001; Thu, 11 Aug 2022 22:34:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AB1768E0005; Thu, 11 Aug 2022 22:34:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 9C4C78E0001 for ; Thu, 11 Aug 2022 22:34:40 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 6F222A1A63 for ; Fri, 12 Aug 2022 02:34:40 +0000 (UTC) X-FDA: 79789372320.01.AF035F8 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf23.hostedemail.com (Postfix) with ESMTP id 83AE914016C for ; Fri, 12 Aug 2022 02:34:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660271679; x=1691807679; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=qh40Lm/37pv5tGRPKccggrBuhhWLRJDlyqjgNjVAxKo=; b=bu//Ao/xIPJDxgayc1u56vleqmjH7K7kiK+cPgK98X5IOn93x8fwyKtZ tyytR9ESANBEyC/UidTPPinvsm+ETPyWTDlHsrxSKWuuAGT76YMD6c8YW 4TTQzl4Bx2rYfC9r0sVgTk+VaS7thOP4+Y+jm/Qzw4r0zLxjl8MPWzAnf dz6ZvWfusGbQQP14X+CZw+fmDfFceZuWvMncO31Jh6j5d6W0IxEfiDUqH f2wqQl7cSVK2ghe0ThcfII9sQ07smATHAo5wYJz3/GrtGPdnGSfnApEF7 bbiTiHVArmtmQNza5ZStWMfuUqEl7iMEFWfZFy9xtrSmwl7LbqbET+2Aa g==; X-IronPort-AV: E=McAfee;i="6400,9594,10436"; a="317474161" X-IronPort-AV: E=Sophos;i="5.93,231,1654585200"; d="scan'208";a="317474161" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Aug 2022 19:34:38 -0700 X-IronPort-AV: E=Sophos;i="5.93,231,1654585200"; d="scan'208";a="851419826" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Aug 2022 19:34:35 -0700 From: "Huang, Ying" To: Peter Xu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , "Kirill A . Shutemov" , Alistair Popple , Andrea Arcangeli , Minchan Kim , Andrew Morton , David Hildenbrand , Andi Kleen , Nadav Amit , Vlastimil Babka Subject: Re: [PATCH v4 6/7] mm/swap: Cache maximum swapfile size when init swap References: <20220811161331.37055-1-peterx@redhat.com> <20220811161331.37055-7-peterx@redhat.com> Date: Fri, 12 Aug 2022 10:34:32 +0800 In-Reply-To: <20220811161331.37055-7-peterx@redhat.com> (Peter Xu's message of "Thu, 11 Aug 2022 12:13:30 -0400") Message-ID: <87h72idwav.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660271679; a=rsa-sha256; cv=none; b=X0EJoiyHrqewDkTu+1ATNh0+cTvre5rVbA3hkzUzqEIzL98KRBaL/uAHQntUdv8ivv+Q0g McdmQRC81V/EqzhaR2hR+CFMOmjWjPNGjVQiTgJGOpaU2VV3A/WSKGocoL6kj0aD0N4m2N 731fsarpGMqN8B9oB0Pd3g9uWkxs5i0= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b="bu//Ao/x"; spf=pass (imf23.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.88 as permitted sender) smtp.mailfrom=ying.huang@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660271679; 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-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=VXO4dc2bFTeYp8/PkB6y01r2lOVfwAMJpWsQFTlFNJY=; b=5G+7sVW6XbSaipjIAUlOsJiufm9aBaVl8F7FSMnHdcUXz73Qj6+cTK0Og5lbdLpYEEoFAQ BLSKVmm/VXs8SJs0RImtQLPpvC8I5LTVH8oTlmUiXKtlfLZTqMWjFdtldbRkdv4SRMLETZ /LiQuZocBobwc6hF7KSWGRjBbPyNcT0= X-Rspamd-Queue-Id: 83AE914016C Authentication-Results: imf23.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b="bu//Ao/x"; spf=pass (imf23.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.88 as permitted sender) smtp.mailfrom=ying.huang@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: 5riumrty9ze8kqerar35tsyaghosqcjr X-HE-Tag: 1660271679-663325 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: Peter Xu writes: > 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(). > > Signed-off-by: Peter Xu LGTM. Reviewed-by: "Huang, Ying" Best Regards, Huang, Ying > --- > 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(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index 82a042c03824..9121bc1b9453 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -1054,7 +1054,7 @@ void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache) > } > > #ifdef CONFIG_SWAP > -unsigned long max_swapfile_size(void) > +unsigned long arch_max_swapfile_size(void) > { > unsigned long pages; > > diff --git a/include/linux/swapfile.h b/include/linux/swapfile.h > index 54078542134c..165e0bd04862 100644 > --- a/include/linux/swapfile.h > +++ b/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 */ > diff --git a/include/linux/swapops.h b/include/linux/swapops.h > index 36e462e116af..f25b566643f1 100644 > --- a/include/linux/swapops.h > +++ b/include/linux/swapops.h > @@ -307,7 +307,7 @@ static inline bool migration_entry_supports_ad(void) > * 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 */ > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 1fdccd2f1422..3cc64399df44 100644 > --- a/mm/swapfile.c > +++ b/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(void) > } > > /* 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(struct swap_info_struct *p, > 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);