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mx.microsoft.com 1; spf=pass smtp.mailfrom=nutanix.com; dmarc=pass action=none header.from=nutanix.com; dkim=pass header.d=nutanix.com; arc=none Authentication-Results: linux-foundation.org; dkim=none (message not signed) header.d=none;linux-foundation.org; dmarc=none action=none header.from=nutanix.com; Received: from DM6PR02MB5578.namprd02.prod.outlook.com (2603:10b6:5:79::13) by DM5PR02MB2217.namprd02.prod.outlook.com (2603:10b6:3:52::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.27; Wed, 14 Jul 2021 15:24:53 +0000 Received: from DM6PR02MB5578.namprd02.prod.outlook.com ([fe80::159:22bc:800a:52b8]) by DM6PR02MB5578.namprd02.prod.outlook.com ([fe80::159:22bc:800a:52b8%6]) with mapi id 15.20.4308.027; Wed, 14 Jul 2021 15:24:53 +0000 From: Tiberiu Georgescu To: akpm@linux-foundation.org, peterx@redhat.com, catalin.marinas@arm.com, peterz@infradead.org, chinwen.chang@mediatek.com, linmiaohe@huawei.com, jannh@google.com, apopple@nvidia.com, christian.brauner@ubuntu.com, ebiederm@xmission.com, adobriyan@gmail.com, songmuchun@bytedance.com, axboe@kernel.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: ivan.teterevkov@nutanix.com, florian.schmidt@nutanix.com, carl.waldspurger@nutanix.com, Tiberiu Georgescu Subject: [RFC PATCH 1/1] pagemap: report swap location for shared pages Date: Wed, 14 Jul 2021 15:24:26 +0000 Message-Id: <20210714152426.216217-2-tiberiu.georgescu@nutanix.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210714152426.216217-1-tiberiu.georgescu@nutanix.com> References: <20210714152426.216217-1-tiberiu.georgescu@nutanix.com> X-ClientProxiedBy: SJ0PR03CA0018.namprd03.prod.outlook.com (2603:10b6:a03:33a::23) To DM6PR02MB5578.namprd02.prod.outlook.com (2603:10b6:5:79::13) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from tiberiu-georgescu.ubvm.nutanix.com (192.146.154.243) by SJ0PR03CA0018.namprd03.prod.outlook.com (2603:10b6:a03:33a::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4331.21 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 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 X-OriginatorOrg: nutanix.com X-MS-Exchange-CrossTenant-Network-Message-Id: f76a7b3b-0025-4fe6-c9bd-08d946db875d X-MS-Exchange-CrossTenant-AuthSource: DM6PR02MB5578.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Jul 2021 15:24:53.6596 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: bb047546-786f-4de1-bd75-24e5b6f79043 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: M/5vN0vHMB+xDfBNagutG1MAMGqtZWH8J5IBW2pqhL4UohzuJHtcU4XgDoMM+s6vGrJ4q6oHP2gYvcG4vJBEqKOB6gU7s5oZ6A57cdVMZ8Q= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR02MB2217 X-Proofpoint-ORIG-GUID: IWzL6dPnnL7w0FrUPxMGsOHO4anVNxiv X-Proofpoint-GUID: IWzL6dPnnL7w0FrUPxMGsOHO4anVNxiv X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-07-14_08:2021-07-14,2021-07-14 signatures=0 X-Proofpoint-Spam-Reason: safe Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org When a page allocated using the MAP_SHARED flag is swapped out, its pagemap entry is cleared. In many cases, there is no difference between swapped-out shared pages and newly allocated, non-dirty pages in the pagemap interface. This patch addresses the behaviour and modifies pte_to_pagemap_entry() to make use of the XArray associated with the virtual memory area struct passed as an argument. The XArray contains the location of virtual pages in the page cache, swap cache or on disk. If they are on either of the caches, then the original implementation still works. If not, then the missing information will be retrieved from the XArray. Co-developed-by: Florian Schmidt Signed-off-by: Florian Schmidt Co-developed-by: Carl Waldspurger Signed-off-by: Carl Waldspurger Co-developed-by: Ivan Teterevkov Signed-off-by: Ivan Teterevkov Signed-off-by: Tiberiu Georgescu --- fs/proc/task_mmu.c | 37 +++++++++++++++++++++++++++++-------- 1 file changed, 29 insertions(+), 8 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index eb97468dfe4c..b17c8aedd32e 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1359,12 +1359,25 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end, return err; } +static void *get_xa_entry_at_vma_addr(struct vm_area_struct *vma, + unsigned long addr) +{ + struct inode *inode = file_inode(vma->vm_file); + struct address_space *mapping = inode->i_mapping; + pgoff_t offset = linear_page_index(vma, addr); + + return xa_load(&mapping->i_pages, offset); +} + static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm, struct vm_area_struct *vma, unsigned long addr, pte_t pte) { u64 frame = 0, flags = 0; struct page *page = NULL; + if (vma->vm_flags & VM_SOFTDIRTY) + flags |= PM_SOFT_DIRTY; + if (pte_present(pte)) { if (pm->show_pfn) frame = pte_pfn(pte); @@ -1374,13 +1387,22 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm, flags |= PM_SOFT_DIRTY; if (pte_uffd_wp(pte)) flags |= PM_UFFD_WP; - } else if (is_swap_pte(pte)) { + } else if (is_swap_pte(pte) || shmem_file(vma->vm_file)) { swp_entry_t entry; - if (pte_swp_soft_dirty(pte)) - flags |= PM_SOFT_DIRTY; - if (pte_swp_uffd_wp(pte)) - flags |= PM_UFFD_WP; - entry = pte_to_swp_entry(pte); + if (is_swap_pte(pte)) { + entry = pte_to_swp_entry(pte); + if (pte_swp_soft_dirty(pte)) + flags |= PM_SOFT_DIRTY; + if (pte_swp_uffd_wp(pte)) + flags |= PM_UFFD_WP; + } else { + void *xa_entry = get_xa_entry_at_vma_addr(vma, addr); + + if (xa_is_value(xa_entry)) + entry = radix_to_swp_entry(xa_entry); + else + goto out; + } if (pm->show_pfn) frame = swp_type(entry) | (swp_offset(entry) << MAX_SWAPFILES_SHIFT); @@ -1393,9 +1415,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm, flags |= PM_FILE; if (page && page_mapcount(page) == 1) flags |= PM_MMAP_EXCLUSIVE; - if (vma->vm_flags & VM_SOFTDIRTY) - flags |= PM_SOFT_DIRTY; +out: return make_pme(frame, flags); }