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 BB1F5C433EF for ; Mon, 27 Jun 2022 06:56:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 08ECA6B0071; Mon, 27 Jun 2022 02:56:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 03E756B0072; Mon, 27 Jun 2022 02:56:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E49748E0001; Mon, 27 Jun 2022 02:56:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id D596A6B0071 for ; Mon, 27 Jun 2022 02:56:00 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id ABB2B80EB0 for ; Mon, 27 Jun 2022 06:56:00 +0000 (UTC) X-FDA: 79623106080.14.9BCDAC3 Received: from mail-pj1-f47.google.com (mail-pj1-f47.google.com [209.85.216.47]) by imf17.hostedemail.com (Postfix) with ESMTP id DCBDB4001C for ; Mon, 27 Jun 2022 06:55:57 +0000 (UTC) Received: by mail-pj1-f47.google.com with SMTP id h9-20020a17090a648900b001ecb8596e43so8477943pjj.5 for ; Sun, 26 Jun 2022 23:55:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=s6YskhKblBTp6d670n0jUd5N1jVCJFrPSjByo6zg+n4=; b=iSYaiX/dx41GqEc0XwQdpzKEEbHBUo9kx8Vgzp9oZKa00sHUJh62oNgysgOzrmkJDZ +oCrpo19mNHhUz7L/tjW4p3PLH8+eIsWY1Xt4VIVulxeZJWdS6XJKHHeZAzpTsgggpoq X+YPxjaAe7YB31/TJsLpXN6WYsSx15i8hR1rNWz5TyntA1jmAgEKdztNsfay9vh5gY0e KlnXNKKV/Hqc+8rAULiQlB0cxozLlBRuPqxRO8zNIGx8Iu36PTLDYToBCgRrMhi0Z8gO hcqnEEPfRNztvyJtdGp8WWNC2sElnhLGjmp4aowBJgDqMkN/CeIbqhkONZOP1Pl+mk1t 2XUw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=s6YskhKblBTp6d670n0jUd5N1jVCJFrPSjByo6zg+n4=; b=HDvHIP2NLpPLArNMVPbh3qBdRyMqTwlLaOkfAFFcEtJ1Zs4ZU4nQOyk8lzk2Ub0luy MvDjXQIqVk0ZPiiMxhzmSWMG7lyv744eNvV6xFpGfWhpQYul09ADJ/D/rKkeFJIy6FYj QFSPNm8nFmzinsiNf3D7ikVzpm3f1OMX1ZSnd+fv95ifg3CgmHuBblD3rWHGtJExqW9p aLBLIk+ERHyxx7JTxyNx6KAnUd8LtTWZSmnmSxdw/FpstYtaH9hvXB1kkxXhRumSJ+9j HE2em453rgZ3zj1nYjJRdYtzfD8UCB5FxQMfS8dTx1GTvESvoC6Bq8g7W4e22+Rqhs8I SYSA== X-Gm-Message-State: AJIora/2MWesEKskCp52gb84tDyGh37NEhAwaMcFee0t6dN0OUgNQMMT 1irEg7A1+E4IhkoehP/JO4y/1w== X-Google-Smtp-Source: AGRyM1vhoRU/LPowseuW576E5KPJwNpI7Hlzq51YcTSiqutzHyiBJhj5MmrUhAowVihcR5nXchQXvA== X-Received: by 2002:a17:90a:1c09:b0:1ea:91d4:5a7f with SMTP id s9-20020a17090a1c0900b001ea91d45a7fmr19569048pjs.232.1656312956629; Sun, 26 Jun 2022 23:55:56 -0700 (PDT) Received: from [10.4.214.173] ([139.177.225.237]) by smtp.gmail.com with ESMTPSA id y27-20020a634b1b000000b0040cff9def93sm6224491pga.66.2022.06.26.23.55.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 26 Jun 2022 23:55:56 -0700 (PDT) Message-ID: <037fc8c3-9b71-cb83-8882-95d5459a494f@bytedance.com> Date: Mon, 27 Jun 2022 14:55:50 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH] mm: hugetlb: kill set_huge_swap_pte_at() Content-Language: en-US To: Anshuman Khandual , mike.kravetz@oracle.com, songmuchun@bytedance.com, akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20220626145717.53572-1-zhengqi.arch@bytedance.com> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656312960; a=rsa-sha256; cv=none; b=bIVKisc4pUBHVlE8gwBrQoYdOMNb4vPuQjS+z73I62kDhxqlzZq6NQD7YMOlbqj+XQ413K UzQCq99/CDBAy75fueSv0t+/NV/GyKoRiNl5LNt53kb+TA38+ABRz8cVSQUTPeQRcZsLbn xybgrMLqiQGiyios51d5I7xyURaKZoI= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b="iSYaiX/d"; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf17.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.216.47 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656312960; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=s6YskhKblBTp6d670n0jUd5N1jVCJFrPSjByo6zg+n4=; b=XiKCKVTIABZJKzfOGR0ohF08TelcEy4YoczodUvGjCUWJUkVPB7RXgndRYrJXUQhYOd5vv +lY103IcxLstGNWEwyuqMXg60srCKkZ2sOEHXIVA2YdVTZaF0uNLMJaPcMbTcG9rssGXZT 5sWvbajXqJzk/GWrOIr414nn45lAa00= X-Stat-Signature: 3rkzaec3ey14wrizkqxxouy719s1o8hf X-Rspamd-Queue-Id: DCBDB4001C Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b="iSYaiX/d"; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf17.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.216.47 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1656312957-387588 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: On 2022/6/27 14:18, Anshuman Khandual wrote: > > > On 6/26/22 20:27, Qi Zheng wrote: >> The commit e5251fd43007 ("mm/hugetlb: introduce set_huge_swap_pte_at() >> helper") add set_huge_swap_pte_at() to handle swap entries on >> architectures that support hugepages consisting of contiguous ptes. >> And currently the set_huge_swap_pte_at() is only overridden by arm64. >> >> The set_huge_swap_pte_at() provide a sz parameter to help determine >> the number of entries to be updated. But in fact, all hugetlb swap >> entries contain pfn information, so we can find the corresponding >> folio through the pfn recorded in the swap entry, then the folio_size() >> is the number of entries that need to be updated. >> >> And considering that users will easily cause bugs by ignoring the >> difference between set_huge_swap_pte_at() and set_huge_pte_at(). >> Let's handle swap entries in set_huge_pte_at() and remove the >> set_huge_swap_pte_at(), then we can call set_huge_pte_at() >> anywhere, which simplifies our coding. >> >> Signed-off-by: Qi Zheng >> --- >> arch/arm64/include/asm/hugetlb.h | 3 --- >> arch/arm64/mm/hugetlbpage.c | 34 ++++++++++++++++---------------- >> include/linux/hugetlb.h | 13 ------------ >> mm/hugetlb.c | 8 +++----- >> mm/rmap.c | 11 +++-------- >> 5 files changed, 23 insertions(+), 46 deletions(-) >> >> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h >> index 1fd2846dbefe..d20f5da2d76f 100644 >> --- a/arch/arm64/include/asm/hugetlb.h >> +++ b/arch/arm64/include/asm/hugetlb.h >> @@ -46,9 +46,6 @@ extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr, >> pte_t *ptep, unsigned long sz); >> #define __HAVE_ARCH_HUGE_PTEP_GET >> extern pte_t huge_ptep_get(pte_t *ptep); >> -extern void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr, >> - pte_t *ptep, pte_t pte, unsigned long sz); >> -#define set_huge_swap_pte_at set_huge_swap_pte_at >> >> void __init arm64_hugetlb_cma_reserve(void); >> >> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c >> index c9e076683e5d..58b89b9d13e0 100644 >> --- a/arch/arm64/mm/hugetlbpage.c >> +++ b/arch/arm64/mm/hugetlbpage.c >> @@ -238,6 +238,13 @@ static void clear_flush(struct mm_struct *mm, >> flush_tlb_range(&vma, saddr, addr); >> } >> >> +static inline struct folio *hugetlb_swap_entry_to_folio(swp_entry_t entry) >> +{ >> + VM_BUG_ON(!is_migration_entry(entry) && !is_hwpoison_entry(entry)); >> + >> + return page_folio(pfn_to_page(swp_offset(entry))); >> +} > > Extracting this huge page size from swap entry is an additional operation which > will increase the over all cost for set_huge_swap_pte_at(). At present the size Hmm, I think this cost is very small. And replacing set_huge_swap_pte_at() by transparently handling swap entries helps reduce possible bugs, which is worthwhile. > value is readily available near set_huge_swap_pte_at() call sites. -- Thanks, Qi