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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0F1E5C433F5 for ; Fri, 6 May 2022 03:39:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=W+dezRDUf/sCTdNxj9RYLZ4ytIWNm1QIojdl2v8stcA=; b=Muf2OnKgPxJlk5 Vj17QHoBCBOebEkzjibMreAQWg0yjKYft/nwNuTEhVJOjg8Ca98beIf2tWjsLw1o/FYgflEYGAiT1 GMDwY8ud9+ftGbsEebK6PpY9CvJb0PKhJXnV+4CueqJ+uzUTKTm3EdMyjWnLgdaDps2fq9He/Fd5Y jyuqXa1Ns0NUEnBFs0xMBvUviWIz1P2xV7Ou/7f57pBTt2kZwQ+6Ap7M91LlYERcAt2upBLmgtDlQ AxV31Qb5fAw1UtgbgTm+sM/dZ3vqKI3mGNz+eijtfkp37OzCfcZj93McivxHfPon7yeumUxW4HekA L7wSEpRKBjF39nhkBqUQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmond-001CpX-3Z; Fri, 06 May 2022 03:38:37 +0000 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmonX-001Cn7-Uw for linux-arm-kernel@lists.infradead.org; Fri, 06 May 2022 03:38:34 +0000 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R191e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04426; MF=baolin.wang@linux.alibaba.com; NM=1; PH=DS; RN=30; SR=0; TI=SMTPD_---0VCPvMM9_1651808302; Received: from 30.32.96.193(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VCPvMM9_1651808302) by smtp.aliyun-inc.com(127.0.0.1); Fri, 06 May 2022 11:38:24 +0800 Message-ID: <21b11024-e893-8c11-9b98-ab1d13413b61@linux.alibaba.com> Date: Fri, 6 May 2022 11:39:05 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration To: Mike Kravetz , akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org Cc: tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org References: <11b92502b3df0e0bba6a1dc71476d79cab6c79ba.1651216964.git.baolin.wang@linux.alibaba.com> <5cab0eca-9630-a7c6-4f5d-5cb45ff82c83@oracle.com> From: Baolin Wang In-Reply-To: <5cab0eca-9630-a7c6-4f5d-5cb45ff82c83@oracle.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220505_203832_207757_91B760EF X-CRM114-Status: GOOD ( 15.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/6/2022 7:53 AM, Mike Kravetz wrote: > On 4/29/22 01:14, Baolin Wang wrote: >> On some architectures (like ARM64), it can support CONT-PTE/PMD size >> hugetlb, which means it can support not only PMD/PUD size hugetlb: >> 2M and 1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page >> size specified. > >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 6fdd198..7cf2408 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1924,13 +1924,15 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, >> break; >> } >> } >> + >> + /* Nuke the hugetlb page table entry */ >> + pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); >> } else { >> flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); >> + /* Nuke the page table entry. */ >> + pteval = ptep_clear_flush(vma, address, pvmw.pte); >> } >> > > On arm64 with CONT-PTE/PMD the returned pteval will have dirty or young set > if ANY of the PTE/PMDs had dirty or young set. Right. > >> - /* Nuke the page table entry. */ >> - pteval = ptep_clear_flush(vma, address, pvmw.pte); >> - >> /* Set the dirty flag on the folio now the pte is gone. */ >> if (pte_dirty(pteval)) >> folio_mark_dirty(folio); >> @@ -2015,7 +2017,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, >> pte_t swp_pte; >> >> if (arch_unmap_one(mm, vma, address, pteval) < 0) { >> - set_pte_at(mm, address, pvmw.pte, pteval); >> + if (folio_test_hugetlb(folio)) >> + set_huge_pte_at(mm, address, pvmw.pte, pteval); > > And, we will use that pteval for ALL the PTE/PMDs here. So, we would set > the dirty or young bit in ALL PTE/PMDs. > > Could that cause any issues? May be more of a question for the arm64 people. I don't think this will cause any issues. Since the hugetlb can not be split, and we should not lose the the dirty or young state if any subpages were set. Meanwhile we already did like this in hugetlb.c: pte = huge_ptep_get_and_clear(mm, address, ptep); tlb_remove_huge_tlb_entry(h, tlb, ptep, address); if (huge_pte_dirty(pte)) set_page_dirty(page); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel