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Mon, 7 Jun 2021 07:59:31 +0000 From: Alistair Popple To: , CC: , , , , , , , , , , , , , Alistair Popple Subject: [PATCH v10 06/10] mm/memory.c: Allow different return codes for copy_nonpresent_pte() Date: Mon, 7 Jun 2021 17:58:51 +1000 Message-ID: <20210607075855.5084-7-apopple@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210607075855.5084-1-apopple@nvidia.com> References: <20210607075855.5084-1-apopple@nvidia.com> MIME-Version: 1.0 X-Originating-IP: [172.20.187.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 5098706e-7dbf-434d-45e7-08d9298a2f3f X-MS-TrafficTypeDiagnostic: BYAPR12MB4983: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:7219; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.112.34;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:schybrid03.nvidia.com;CAT:NONE;SFS:(4636009)(136003)(39860400002)(346002)(396003)(376002)(46966006)(36840700001)(4326008)(5660300002)(36906005)(54906003)(110136005)(82310400003)(6666004)(82740400003)(107886003)(316002)(2906002)(356005)(83380400001)(47076005)(7416002)(36756003)(26005)(186003)(36860700001)(1076003)(426003)(8676002)(2616005)(8936002)(478600001)(70586007)(7636003)(70206006)(336012)(86362001)(16526019);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jun 2021 07:59:32.3404 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5098706e-7dbf-434d-45e7-08d9298a2f3f X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.34];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT059.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR12MB4983 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C8A15A000151 Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b="dpa4o/l0"; dmarc=pass (policy=none) header.from=nvidia.com; spf=none (imf15.hostedemail.com: domain of apopple@nvidia.com has no SPF policy when checking 40.107.237.83) smtp.mailfrom=apopple@nvidia.com X-Stat-Signature: yzfkbzuhk61qxiqimojzimtpy3zbeh97 X-HE-Tag: 1623052772-123926 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: Currently if copy_nonpresent_pte() returns a non-zero value it is assumed to be a swap entry which requires further processing outside the loop in copy_pte_range() after dropping locks. This prevents other values being returned to signal conditions such as failure which a subsequent change requires. Instead make copy_nonpresent_pte() return an error code if further processing is required and read the value for the swap entry in the main loop under the ptl. Signed-off-by: Alistair Popple Reviewed-by: Peter Xu --- v10: Use a unique error code and only check return codes for handling. v9: New for v9 to allow device exclusive handling to occur in copy_nonpresent_pte(). --- mm/memory.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 2fb455c365c2..0982cab37ecb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -718,7 +718,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, if (likely(!non_swap_entry(entry))) { if (swap_duplicate(entry) < 0) - return entry.val; + return -EIO; /* make sure dst_mm is on swapoff's mmlist. */ if (unlikely(list_empty(&dst_mm->mmlist))) { @@ -974,11 +974,13 @@ copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, continue; } if (unlikely(!pte_present(*src_pte))) { - entry.val = copy_nonpresent_pte(dst_mm, src_mm, - dst_pte, src_pte, - src_vma, addr, rss); - if (entry.val) + ret = copy_nonpresent_pte(dst_mm, src_mm, + dst_pte, src_pte, + src_vma, addr, rss); + if (ret == -EIO) { + entry = pte_to_swp_entry(*src_pte); break; + } progress += 8; continue; } @@ -1011,20 +1013,24 @@ copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, pte_unmap_unlock(orig_dst_pte, dst_ptl); cond_resched(); - if (entry.val) { + if (ret == -EIO) { + VM_WARN_ON_ONCE(!entry.val); if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) { ret = -ENOMEM; goto out; } entry.val = 0; - } else if (ret) { - WARN_ON_ONCE(ret != -EAGAIN); + } else if (ret == -EAGAIN) { prealloc = page_copy_prealloc(src_mm, src_vma, addr); if (!prealloc) return -ENOMEM; - /* We've captured and resolved the error. Reset, try again. */ - ret = 0; + } else if (ret) { + VM_WARN_ON_ONCE(1); } + + /* We've captured and resolved the error. Reset, try again. */ + ret = 0; + if (addr != end) goto again; out: