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X-IronPort-AV: E=McAfee;i="6500,9779,10555"; a="315005980" X-IronPort-AV: E=Sophos;i="5.96,228,1665471600"; d="scan'208";a="315005980" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Dec 2022 19:16:32 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10555"; a="649416107" X-IronPort-AV: E=Sophos;i="5.96,228,1665471600"; d="scan'208";a="649416107" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Dec 2022 19:16:30 -0800 From: "Huang, Ying" To: Kairui Song Cc: linux-mm@kvack.org, Kairui Song , linux-kernel@vger.kernel.org, Andrew Morton , Miaohe Lin , David Hildenbrand , Hugh Dickins Subject: Re: [PATCH 2/5] swap: avoid a redundant pte map if ra window is 1 References: <20221208180209.50845-1-ryncsn@gmail.com> <20221208180209.50845-3-ryncsn@gmail.com> Date: Fri, 09 Dec 2022 11:15:41 +0800 In-Reply-To: <20221208180209.50845-3-ryncsn@gmail.com> (Kairui Song's message of "Fri, 9 Dec 2022 02:02:06 +0800") Message-ID: <87v8mlqnc2.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 X-Rspam-User: X-Rspamd-Queue-Id: 2B830140007 X-Rspamd-Server: rspam01 X-Stat-Signature: ju1jb5eh7smgt3wzs1n5cybkhra7psxy X-HE-Tag: 1670555793-647856 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: Kairui Song writes: > From: Kairui Song > > Avoid a redundant pte map/unmap when swap readahead window is 1. > > Signed-off-by: Kairui Song > --- > mm/swap_state.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) Good to reduce the line of code. Thanks! Reviewed-by: "Huang, Ying" > diff --git a/mm/swap_state.c b/mm/swap_state.c > index 438d0676c5be..60136bda78e3 100644 > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -730,8 +730,6 @@ static void swap_ra_info(struct vm_fault *vmf, > } > > faddr = vmf->address; > - orig_pte = pte = pte_offset_map(vmf->pmd, faddr); > - > fpfn = PFN_DOWN(faddr); > ra_val = GET_SWAP_RA_VAL(vma); > pfn = PFN_DOWN(SWAP_RA_ADDR(ra_val)); > @@ -742,12 +740,11 @@ static void swap_ra_info(struct vm_fault *vmf, > atomic_long_set(&vma->swap_readahead_info, > SWAP_RA_VAL(faddr, win, 0)); > > - if (win == 1) { > - pte_unmap(orig_pte); > + if (win == 1) > return; > - } > > /* Copy the PTEs because the page table may be unmapped */ > + orig_pte = pte = pte_offset_map(vmf->pmd, faddr); > if (fpfn == pfn + 1) > swap_ra_clamp_pfn(vma, faddr, fpfn, fpfn + win, &start, &end); > else if (pfn == fpfn + 1)