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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Steven Rostedt , Masami Hiramatsu , "Mathieu Desnoyers" , Zach O'Keefe , , , , , Branden Moore Subject: [PATCH V3 1/2] mm/khugepaged: map dirty/writeback pages failures to EAGAIN Date: Mon, 1 Dec 2025 18:56:09 +0000 Message-ID: <20251201185604.210634-8-shivankg@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251201185604.210634-6-shivankg@amd.com> References: <20251201185604.210634-6-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: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS2PEPF0000343B:EE_|LV3PR12MB9267:EE_ X-MS-Office365-Filtering-Correlation-Id: c14d6583-1fbc-499c-53f1-08de310c3e36 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|82310400026|7416014|36860700013|1800799024|13003099007; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?ctxtdUA609rcE/ENAHjARG7zeejxfhcL29IWHJpbPM/72efbF7wVa4uY0esa?= =?us-ascii?Q?DyZU2mNDc8CdH+3jG8PK3F5qPNRb0wMAxuKC4wKz560barDbF2GIQQDn0NvN?= =?us-ascii?Q?DpOmTe5neypQXnV6v4FOfsoY4Yh6KeoY0HCx+4WTbR3STf4dewgemT1+W2bV?= =?us-ascii?Q?p+y+UJigB5PhNnX8Zp1hYCFuD7MNOfhpjGD5Znr/eg+X193g6LyCFokKpKus?= =?us-ascii?Q?cDmKG/yVxwps/z1e3Lwj2FXigqHd5hbqu4NncF0N11jimCx2lVUc+3+aDMNe?= =?us-ascii?Q?OkGAUG6Sxhil9Hvi/aHT7wK/GMLfjGmduJL4u5jC1AdlrhRo0ibZJRGfgGWx?= =?us-ascii?Q?vdFUkOd8oBvOoVd3KUJRUQd61L7KZsGbpD0f4thk6+DDVz3EMMEZhfU6BJb8?= =?us-ascii?Q?xI/fiD2Ic55JXaH/zMB7tZo1rQFRVxYDGEkuN8C53feL71rov46po1e+GmW4?= =?us-ascii?Q?pDPTPuReLIfDm+HL5WCekU9KPFa94ylKKzy6aejLUDL2dyHtabnCt6iAIPt8?= =?us-ascii?Q?eno8R/DWoMWJTNJeBZWK+yis5vMsEmbiphmHX32p0VqIqmP+Jybd8HJNhQoZ?= =?us-ascii?Q?ZqRLiwYDyUwqEZdw7QV+MA8iKize2sXjryxuRsId9ivKRFzr7N/YVWx2xC2f?= =?us-ascii?Q?7CU4OJMwNRqYshKvItW83M644cyZHfwAybm/KaG8tnBb4ZPjPP8A9GlK5P08?= =?us-ascii?Q?lzm0OBA7vkLJ8NR+qggmJyV0I9IEujDiatQhggLSj6Ma7ndM7gbnVZ6ftOLo?= =?us-ascii?Q?HZeql40MmnQ7W9M9aG+1VxDZ61qZAa+4Mxm9JSmRwNcdWxKHoccZ+AixuPmy?= =?us-ascii?Q?w5XZhS0o8ndpYcTcNw+nXLHJEPvi/pUipna/Hh1uKnaStH5g2zk7C+X6312z?= =?us-ascii?Q?r0+1AF9K2TU+y5YHl55iLjRpQEhj8nj7rOXa32ZpQRzIyXm36yK5JWOdlkI0?= =?us-ascii?Q?pKwz1HyycgcUGcjAomIg5NN9o4qZdE4ALslofdxCWWeOCTIThum+C/LNGzaZ?= =?us-ascii?Q?OV0yUF3M6LCh7nT3I/fhVFaCoNqYKG63+dvE8GP8ET13xpuDBasjgw9vz8DM?= =?us-ascii?Q?yZgKp9j8gTciwhoeYV0U6HCmQrFbX3HeUxMWpne+kAVsIfRPA6Pu2eCifIY5?= =?us-ascii?Q?A7qwNasWU3TMOkeYvw05iDo1GrrDVsCtmgAMTxYct1/aR4WwdRKkDJAmjcuN?= =?us-ascii?Q?G9qDghktCFNqFjBo/cP71BPOH/gbMsVIWU7B7Hd0lwqLyy+T+BTWSLeAAl6O?= =?us-ascii?Q?Tc1LQiruvi+xxfC/OYSg3GxmFu5+RVQuzqEUFIiPKvHGyz/fP23cxsJmKx3u?= =?us-ascii?Q?vvno2ZPKEQlYBTXTOHj7Jl9oVu1XfIk0hrDiDBHUjIFGcO6lTLiw6oGFe7us?= =?us-ascii?Q?zmZsP74RJk/uRLfu2j/mnMZeF1E5fZyxY3fAjoYxskpF6bWL6R6aiU37zkGV?= =?us-ascii?Q?1ge9avjZo1twz21+UT5a23jCF/EKWnrlRYlohUSVLx/he14erscf+Wm/VdRn?= =?us-ascii?Q?w1ULGRQ7ICPFgtKW3ajOYM3/HfQRDDWPGFul?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(82310400026)(7416014)(36860700013)(1800799024)(13003099007);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Dec 2025 19:02:58.5487 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c14d6583-1fbc-499c-53f1-08de310c3e36 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: DS2PEPF0000343B.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV3PR12MB9267 Content-Type: text/plain; charset="utf-8" When collapse_file encounters dirty or writeback pages in file-backed mappings, it currently returns SCAN_FAIL which maps to -EINVAL. This is misleading as EINVAL suggests invalid arguments, whereas dirty/writeback pages represent transient conditions that may resolve on retry. Introduce SCAN_PAGE_DIRTY_OR_WRITEBACK to cover both dirty and writeback states, mapping it to -EAGAIN. For MADV_COLLAPSE, this provides userspace with a clear signal that retry may succeed after writeback completes. For khugepaged, this is harmless as it will naturally revisit the range during periodic scans after async writeback completes. 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") Reviewed-by: Dev Jain Reviewed-by: Lance Yang Signed-off-by: Shivank Garg --- include/trace/events/huge_memory.h | 3 ++- mm/khugepaged.c | 8 +++++--- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge= _memory.h index 4cde53b45a85..4e41bff31888 100644 --- a/include/trace/events/huge_memory.h +++ b/include/trace/events/huge_memory.h @@ -37,7 +37,8 @@ EM( SCAN_PAGE_HAS_PRIVATE, "page_has_private") \ EM( SCAN_STORE_FAILED, "store_failed") \ EM( SCAN_COPY_MC, "copy_poisoned_page") \ - EMe(SCAN_PAGE_FILLED, "page_filled") + EM( SCAN_PAGE_FILLED, "page_filled") \ + EMe(SCAN_PAGE_DIRTY_OR_WRITEBACK, "page_dirty_or_writeback") =20 #undef EM #undef EMe diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 97d1b2824386..219dfa2e523c 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -58,6 +58,7 @@ enum scan_result { SCAN_STORE_FAILED, SCAN_COPY_MC, SCAN_PAGE_FILLED, + SCAN_PAGE_DIRTY_OR_WRITEBACK, }; =20 #define CREATE_TRACE_POINTS @@ -1967,11 +1968,11 @@ static int collapse_file(struct mm_struct *mm, unsi= gned long addr, */ xas_unlock_irq(&xas); filemap_flush(mapping); - result =3D SCAN_FAIL; + result =3D SCAN_PAGE_DIRTY_OR_WRITEBACK; goto xa_unlocked; } else if (folio_test_writeback(folio)) { xas_unlock_irq(&xas); - result =3D SCAN_FAIL; + result =3D SCAN_PAGE_DIRTY_OR_WRITEBACK; goto xa_unlocked; } else if (folio_trylock(folio)) { folio_get(folio); @@ -2018,7 +2019,7 @@ static int collapse_file(struct mm_struct *mm, unsign= ed long addr, * folio is dirty because it hasn't been flushed * since first write. */ - result =3D SCAN_FAIL; + result =3D SCAN_PAGE_DIRTY_OR_WRITEBACK; goto out_unlock; } =20 @@ -2747,6 +2748,7 @@ static int madvise_collapse_errno(enum scan_result r) case SCAN_PAGE_LRU: case SCAN_DEL_PAGE_LRU: case SCAN_PAGE_FILLED: + case SCAN_PAGE_DIRTY_OR_WRITEBACK: return -EAGAIN; /* * Other: Trying again likely not to succeed / error intrinsic to --=20 2.43.0