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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 8E9CFC433EF for ; Fri, 29 Apr 2022 13:09:52 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KqXrv2DRQz3chW for ; Fri, 29 Apr 2022 23:09:51 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.alibaba.com (client-ip=115.124.30.130; helo=out30-130.freemail.mail.aliyun.com; envelope-from=baolin.wang@linux.alibaba.com; receiver=) Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KqQRK3YJwz3bcC for ; Fri, 29 Apr 2022 18:20:45 +1000 (AEST) 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=e01e04394; MF=baolin.wang@linux.alibaba.com; NM=1; PH=DS; RN=31; SR=0; TI=SMTPD_---0VBgmob1_1651220115; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VBgmob1_1651220115) by smtp.aliyun-inc.com(127.0.0.1); Fri, 29 Apr 2022 16:15:16 +0800 From: Baolin Wang To: akpm@linux-foundation.org, mike.kravetz@oracle.com, catalin.marinas@arm.com, will@kernel.org Subject: [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Date: Fri, 29 Apr 2022 16:14:43 +0800 Message-Id: X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: X-Mailman-Approved-At: Fri, 29 Apr 2022 23:08:22 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dalias@libc.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, James.Bottomley@HansenPartnership.com, linux-mm@kvack.org, paulus@samba.org, sparclinux@vger.kernel.org, agordeev@linux.ibm.com, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, arnd@arndb.de, ysato@users.sourceforge.jp, deller@gmx.de, borntraeger@linux.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com, baolin.wang@linux.alibaba.com, linux-arm-kernel@lists.infradead.org, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, linux-mips@vger.kernel.org, svens@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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. When unmapping a hugetlb page, we will get the relevant page table entry by huge_pte_offset() only once to nuke it. This is correct for PMD or PUD size hugetlb, since they always contain only one pmd entry or pud entry in the page table. However this is incorrect for CONT-PTE and CONT-PMD size hugetlb, since they can contain several continuous pte or pmd entry with same page table attributes, so we will nuke only one pte or pmd entry for this CONT-PTE/PMD size hugetlb page. And now we only use try_to_unmap() to unmap a poisoned hugetlb page, which means now we will unmap only one pte entry for a CONT-PTE or CONT-PMD size poisoned hugetlb page, and we can still access other subpages of a CONT-PTE or CONT-PMD size poisoned hugetlb page, which will cause serious issues possibly. So we should change to use huge_ptep_clear_flush() to nuke the hugetlb page table to fix this issue, which already considered CONT-PTE and CONT-PMD size hugetlb. Note we've already used set_huge_swap_pte_at() to set a poisoned swap entry for a poisoned hugetlb page. Signed-off-by: Baolin Wang --- mm/rmap.c | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 7cf2408..1e168d7 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1564,28 +1564,28 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, break; } } + pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); } else { flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); - } - - /* - * Nuke the page table entry. When having to clear - * PageAnonExclusive(), we always have to flush. - */ - if (should_defer_flush(mm, flags) && !anon_exclusive) { /* - * We clear the PTE but do not flush so potentially - * a remote CPU could still be writing to the folio. - * If the entry was previously clean then the - * architecture must guarantee that a clear->dirty - * transition on a cached TLB entry is written through - * and traps if the PTE is unmapped. + * Nuke the page table entry. When having to clear + * PageAnonExclusive(), we always have to flush. */ - pteval = ptep_get_and_clear(mm, address, pvmw.pte); + if (should_defer_flush(mm, flags) && !anon_exclusive) { + /* + * We clear the PTE but do not flush so potentially + * a remote CPU could still be writing to the folio. + * If the entry was previously clean then the + * architecture must guarantee that a clear->dirty + * transition on a cached TLB entry is written through + * and traps if the PTE is unmapped. + */ + pteval = ptep_get_and_clear(mm, address, pvmw.pte); - set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); - } else { - pteval = ptep_clear_flush(vma, address, pvmw.pte); + set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); + } else { + pteval = ptep_clear_flush(vma, address, pvmw.pte); + } } /* -- 1.8.3.1