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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 , wang lian Subject: [PATCH V4 1/2] mm/khugepaged: map dirty/writeback pages failures to EAGAIN Date: Mon, 15 Dec 2025 08:46:17 +0000 Message-ID: <20251215084615.5283-5-shivankg@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251215084615.5283-3-shivankg@amd.com> References: <20251215084615.5283-3-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: SJ5PEPF000001D2:EE_|IA1PR12MB9738:EE_ X-MS-Office365-Filtering-Correlation-Id: 109f7568-8e65-4bfe-9ec0-08de3bb69ef0 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|82310400026|36860700013|1800799024|13003099007; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?E4AUwYqcoxYe1ACX3jKzw+0inOcjalNdf8R6aVSA8SMiAcdTeQI8bfhEdDzo?= =?us-ascii?Q?4c0P9MS+1qy6rfKRgSdzeVNVmgvZpEDbY4PoMgijJyK92O9YDTDIcsZDkNPm?= =?us-ascii?Q?R4Xar1/iapDyOw8G4uF93ZH/RnriVL5vSCPZWXKMvQv2kOIs0V+8+r7pXPBc?= =?us-ascii?Q?6PE1fw647HfP/STKQlOKn/rjxDiPDSriPk7QrrOCQlncTIzzQQDBmqWbWwwW?= =?us-ascii?Q?M9wnCTmYAEVxGC8TYn8ui8Volc7t1MIHfMqB+SrGhhAa75ZxGCbVYKVuRE2+?= =?us-ascii?Q?YZeFLwdRIHs11xHk3UqSiR1PLOqumR+euz2JAnlSXwqcMsaFsnzeGgFI3ef/?= =?us-ascii?Q?bL67nWjRmNI+ymRbEkvRYyBIkQU52ZQE6rEBl+N5Z+r7uRf/i52G5XYdRpy3?= =?us-ascii?Q?+rSgJ7Q8uiqitr9mRvrHNwfWCL8r82YEQgak7KPXLXqVV9cy1+Dvw0VvPdDp?= =?us-ascii?Q?h/SYZOQImmOh/7I76rUa08QXZLnwdsr94EpI5mSGKNiBA6yThHba717Y5MST?= =?us-ascii?Q?+cunxsSk+277nuYdSZBlKRlltHLIT//uzytMbhfMBBLHzzafngEvlaVcOlR6?= =?us-ascii?Q?DMa24sEdMzcrfj7JcaYi7jZVZfiD/owBTeKofefj7ilqVZYCHmL6tPe2a7xT?= =?us-ascii?Q?X9kuHBBqjYfylJye6ZhxSWZMazGwuUNFqb15jyrMYjvNT4Wha1nHk6FWyHxW?= =?us-ascii?Q?occablTvBq4LUHx3JsfcH9SWSoIUF7uc6sj58m09aIK97HHGsKVvq7QzjGsQ?= =?us-ascii?Q?EQ6aB+MGjWQfwj4h4X3CHMxnG80+qCRUNleff/BZf2cRLjbHAlIYj2TVk4Va?= =?us-ascii?Q?SUF/CwzYZSdmOULe89U3577STDvMEensMAJBJhldUoERxAbejcHceWt4QfBQ?= =?us-ascii?Q?I6u6ecbhYlHXIZb/c67Q353uzomP+wreFz+JYEC9ZzmwK5ZNNivKz4V5j72K?= =?us-ascii?Q?G5dcbLVEplGzcb16o/TaKb3dQHfQ63SBuUCOlM5HXMolnwxtb8SfUpn2Zwdu?= =?us-ascii?Q?ZZAWPJy67RoEsMkTa4xxJ7ED/BVbwHncA3IJRiEHqTlLh217MvtkW1y6OVOj?= =?us-ascii?Q?HJsZycewlfcNafFGfMyQsKgV8YQqBGli0QPZhVFCISKgJJeRV0cXOG/bvLei?= =?us-ascii?Q?N5XsV2O3a8Qe6WBKhCeZjm3o9WB0tFdeC9N7o2x/wbA+4q4qCFiLFQf3nrjE?= =?us-ascii?Q?qsCOgqX+EvAN8o6OLw79zIyKO0igx8NQ8L3v8a5eVHUqlnAzgJ92VHUQGz9D?= =?us-ascii?Q?F2A2IIDeXnMNf4AmmB4Ue1OEcwUsC0TrnuFMml6o6PBwgkb5hRBGEKPUgiY9?= =?us-ascii?Q?yG9HMJxtL999nK7e0CLL5JZKFifHNIanJUwtgpusfXoKcoum+bW1PnY9PDZt?= =?us-ascii?Q?D47JbHBfgWJwAkh2hwJBHhuNIWf38djb6+6S5QnGm4cwDyj1d1QnvxH5pffT?= =?us-ascii?Q?6lPyvOYUpJ4Cqtp3yYzsbPaLuXZ7Xa/IM3JxpyY3kQRvxXBpc9VdMIPvfCue?= =?us-ascii?Q?Cq11oC5b9g/QlyQGnpuVb2Rc8D+DHwQP3UjPYNQvVar3X4nLtqKJA2l/KKSq?= =?us-ascii?Q?9aWzv22hQOSRLqb5S3M=3D?= 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)(7416014)(82310400026)(36860700013)(1800799024)(13003099007);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Dec 2025 08:47:46.8510 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 109f7568-8e65-4bfe-9ec0-08de3bb69ef0 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: SJ5PEPF000001D2.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB9738 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 Reviewed-by: Baolin Wang Reviewed-by: wang lian 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