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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Masami Hiramatsu , Steven Rostedt , , Mathieu Desnoyers , Zach O'Keefe , , , Stephen Rothwell , , Branden Moore Subject: [PATCH V5 2/2] mm/khugepaged: retry with sync writeback for MADV_COLLAPSE Date: Sun, 18 Jan 2026 19:09:43 +0000 Message-ID: <20260118190939.8986-7-shivankg@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260118190939.8986-2-shivankg@amd.com> References: <20260118190939.8986-2-shivankg@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN3PEPF0000B06F:EE_|MN2PR12MB4358:EE_ X-MS-Office365-Filtering-Correlation-Id: a8ad3bdd-c9cf-48f0-bbeb-08de56c68287 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|376014|7416014|1800799024|82310400026|13003099007; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?1z/N1d5b8HSymvCZTDCx0QZwMETUjfEjES1zrgj+f+87goM3ElYivKmUG1c+?= =?us-ascii?Q?opiCilFA+MP3glcj5iXfCNABQ/2fH+LY49GPCZg5SUgahJYBcVsgTy3VK/kM?= =?us-ascii?Q?stFWGM79UNZkmqK2KlS30/7MMSQfE0N9Q5bGLElJRY9OhhkfYUqz4IqeymrS?= =?us-ascii?Q?hzbzfILpt16HxCAh5RmWFcGbg2dEAGrhEkDZUdbbJ5CdhgnvL8HmIP+OkaPu?= =?us-ascii?Q?pqxnwDVagIT5tYqZVVaB6iYx3DQzPVg0ELHjihpPaAtVyrrExGk4YXeB/w7Y?= =?us-ascii?Q?GFg/UgFby7oyS2NhjTYc/SBYs3LowWBWyQ/TLAgiqRB0qauY81MiIyXZCwIu?= =?us-ascii?Q?CVT4iaV+njocJHMdM7RkUl8RwKCQt0yGZEK5zuV9DEtHWJy5iKt6/434SV57?= =?us-ascii?Q?PdYWlIcorFNVA03HSpZvlJi2rtW2sj4CNi2f3hTTTExoUn991DE9rlQ29BE7?= =?us-ascii?Q?bdFp5rfQuiwfwOCf/ObmKNoU2PUkl+pY8LGDoIHA0mI0qB5YHR3G3RbOmbWD?= =?us-ascii?Q?dhsAlncHtuT3kXq8mTxUDRRYKLtYYGRyBXiAstsZw3e1BwzfInpnkoH2sWPF?= =?us-ascii?Q?b/7mRQ5riXDMfpQkJk30Cr3+p5Ie6K98eTbBy1Vn9wTzOLB0eYBl3EgsMG7e?= =?us-ascii?Q?BXSKIFSKRdx0NvH9hCGU9it2X4y32KmwDh2VKp1MCFE1rOijoFRIeydh3CYQ?= =?us-ascii?Q?3L3VUJZ8JCdaCMC9BooL1ZYBvWbVnXUn68Cgd3r0oMYJpmwdpB2npwGs+hx4?= =?us-ascii?Q?I9FsPjNQ77GnUxsiE2DFZQ+MZSXVzSP+57xs+ItA0vK3Rxj532V+TZfJ242J?= =?us-ascii?Q?hVTgFlKvfwblTdilBBix58dTCtUvMzGLHmMAnjPHpHfRXkbiBd2EBHvRYuKv?= =?us-ascii?Q?QyQPUkfaSx8c5S5iVb8/Ngq//7BSPRLRc6hJAgcGVtr7sBKPA46HNwDX07aU?= =?us-ascii?Q?h5+klMu3OrIEOauClAU4mdcqWE3I0n/buuoOEmxih/oi9Bx0jdkvWkgf0dOj?= =?us-ascii?Q?jLprq6MsKS1imPyM3yNvD3FPAx2MtIHBvMAE0t/voTRGYG8IsfqcOrGMVEG7?= =?us-ascii?Q?KmegzdZC6xnbVBcaYcTXICEpt3Y8hUV4eVI/yMsPgMWrweOJ5z+v+HckZva1?= =?us-ascii?Q?bJ6WRM45NjqOb9ZjUsn6wwvXBH5SV9xW46zr5B/ioWoziN9qXFUq5+TBa7Le?= =?us-ascii?Q?kdpV8iouVkSjoX8tKPWd+YKEV8RlaXtbFpC8Ob3QlPRgGLPxXjKyyPehng2H?= =?us-ascii?Q?MgQ0nHZUwLpFuH0JK3FDZQUOh6fquuRogM/4Z10igxx9DD56DiJPZhE1yp8+?= =?us-ascii?Q?i+iZJ4bpMi8tb5AqSpXFIjyI5ws1XNNmvRMBfVBvFFEINvBCX5eRS0df9BAa?= =?us-ascii?Q?UAXWW2aF136kKSA+claIwyAtr52x7W/Ei32KKGUP3ZIN6Y2msctfRiWWzPtL?= =?us-ascii?Q?l6pXsRzEkV5rI3Qlxv7ejzgvCB6B9iKWYBexSdXZym8UdSKVR4ZMxzSvyhXS?= =?us-ascii?Q?hSX1Y7NXy3Bybdgw5OslX5isgiSnGHExkvcP6547uk7jxe47vlZ9q9D8plsb?= =?us-ascii?Q?vALPbkBKZo8/2xmInMQcAthdPNAVcKYJy5Blm200mfD6CPFV8YDCWj6owhYv?= =?us-ascii?Q?aKJGytKYNEsqg1oPGUcnsco=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(376014)(7416014)(1800799024)(82310400026)(13003099007);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jan 2026 19:19:32.6210 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a8ad3bdd-c9cf-48f0-bbeb-08de56c68287 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN3PEPF0000B06F.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4358 Content-Type: text/plain; charset="utf-8" When MADV_COLLAPSE is called on file-backed mappings (e.g., executable text sections), the pages may still be dirty from recent writes. collapse_file() will trigger async writeback and fail with SCAN_PAGE_DIRTY_OR_WRITEBACK (-EAGAIN). MADV_COLLAPSE is a synchronous operation where userspace expects immediate results. If the collapse fails due to dirty pages, perform synchronous writeback on the specific range and retry once. This avoids spurious failures for freshly written executables while avoiding unnecessary synchronous I/O for mappings that are already clean. Reported-by: Branden Moore Closes: https://lore.kernel.org/all/4e26fe5e-7374-467c-a333-9dd48f85d7cc@am= d.com Fixes: 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAP= SE") Suggested-by: David Hildenbrand Tested-by: Lance Yang Signed-off-by: Shivank Garg Acked-by: David Hildenbrand (Red Hat) Reviewed-by: Dev Jain --- mm/khugepaged.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 219dfa2e523c..16582bdcb6ff 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -22,6 +22,7 @@ #include #include #include +#include =20 #include #include "internal.h" @@ -2788,7 +2789,9 @@ int madvise_collapse(struct vm_area_struct *vma, unsi= gned long start, =20 for (addr =3D hstart; addr < hend; addr +=3D HPAGE_PMD_SIZE) { int result =3D SCAN_FAIL; + bool triggered_wb =3D false; =20 +retry: if (!mmap_locked) { cond_resched(); mmap_read_lock(mm); @@ -2809,8 +2812,20 @@ int madvise_collapse(struct vm_area_struct *vma, uns= igned long start, =20 mmap_read_unlock(mm); mmap_locked =3D false; + *lock_dropped =3D true; result =3D hpage_collapse_scan_file(mm, addr, file, pgoff, cc); + + if (result =3D=3D SCAN_PAGE_DIRTY_OR_WRITEBACK && !triggered_wb && + mapping_can_writeback(file->f_mapping)) { + loff_t lstart =3D (loff_t)pgoff << PAGE_SHIFT; + loff_t lend =3D lstart + HPAGE_PMD_SIZE - 1; + + filemap_write_and_wait_range(file->f_mapping, lstart, lend); + triggered_wb =3D true; + fput(file); + goto retry; + } fput(file); } else { result =3D hpage_collapse_scan_pmd(mm, vma, addr, --=20 2.43.0