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Piccoli" , muralidhara.mk@amd.com, naveenkrishna.chatradhi@amd.com, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] RAS/AMD/FMPM: Fix spurious BUG when ERST record enumeration fails Message-ID: <20260925143004.GA1859103@yaz-khff2.amd.com> References: <20260925030918.3428029-1-qirui.001@bytedance.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260925030918.3428029-1-qirui.001@bytedance.com> X-ClientProxiedBy: BL1PR13CA0210.namprd13.prod.outlook.com (2603:10b6:208:2be::35) To DM4PR12MB6374.namprd12.prod.outlook.com (2603:10b6:8:a3::18) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR12MB6374:EE_|SJ0PR12MB8615:EE_ X-MS-Office365-Filtering-Correlation-Id: 18a99d26-03ad-4bf5-7614-08df1b11baa5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|23010399003|366016|1800799024|10067099003|56012099006|22082099003|18002099003|11063799006; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?euXJg9BQ9mkNBk8PDEFgRJRi68Nh2TVQTo4oJCLFqZ9+lBJy5cf+PIp52D59?= =?us-ascii?Q?CNFqbIUGUAHxmXjzVMjOoOy6ETBA7qhlG30xdCuX79xv19G2dfgdWf5q1gor?= =?us-ascii?Q?6bLjdvPMqCJ21w419nL6pHv4Gae6BExO1u5NXwquhpr6SiZCJ1F+t07ViIlD?= =?us-ascii?Q?CZ9VmpsZzNuJT2xNAIuprlX4E6Nmwd31W/YuqitQv2bzKresQiZ7sKZBOB9F?= =?us-ascii?Q?j3WEyV6uefmCtvxCeq/jpBCGuZn3A8/tIbtzvfuqFtdHCL0y444o+iwcQGx9?= =?us-ascii?Q?5Ytd3tH9HlbmPDbcB18DuyzdcjJc9IQU5rNBW1IweM/dxTiuxcA6y4ZkCdDE?= =?us-ascii?Q?3gijkt5r9Ery2DjSONn1GnsIdZDjQo5sxwM6ZyQTdXELWC1PV9YlZ4VEZ99e?= =?us-ascii?Q?ocoSV+Y3dm7FazcLtzYEW5BpSwwC1i6Ejyxys/x3p825QHI0jAMfvkubFstl?= =?us-ascii?Q?KXX5izE2UrMZhDJbam4LjYEYOF4Px5SWgenHci0vBA4pIImxb4dfGA3hSXgc?= =?us-ascii?Q?gJjkMfBfH2b0kIsnq9wf6g5gHcgvebZzDsb5WzBd7K8V1x63B0h8D7ume5Ga?= =?us-ascii?Q?ttJgjlXIFjJxS51PgKjL/TB5PWlw1McKSCj8jCEr45ogJTCtLHS4R9VodGpy?= =?us-ascii?Q?4Hgyl75X0gvyrDllk4rQdTey60TGLy39TRLM93piR4NgPX5vdoSggdlRgnzM?= =?us-ascii?Q?PKC8RtzcldiF1SPJ8Ca+GyrGeUKOEJfkvZ1axDr6EX1n42sb3Hr4dxkLo3ig?= =?us-ascii?Q?7UKRn6afbldBKKlt4eaPrzynDS4VQmW6Xx0ohuI0W+rVGhIVYjSU4S4ggChO?= =?us-ascii?Q?20K4rPxZT4G4MB/G7136I72YieG3DXaqVJK5/uDn2BARM4khu2SeT3/rRoUv?= =?us-ascii?Q?YG2b8UkIdKHz8GohiApJYf4oNACS7C9gr8HOwmI+67ie3Tf6Pn62OEscdjym?= =?us-ascii?Q?Q7ZWHGJA7meTV3hri1vYygy3ux+qzkorrd4F96eCd8g3c4bHH+TsLUYdDo+H?= =?us-ascii?Q?y4l60+WXnfKXLkZl8RYOqp5Jhjypgt+A/BTx5XKiJ+4zfogLN8kh031ykI6Y?= =?us-ascii?Q?tm7NtDE0LEpfAwQnLE4P0NPhc7juitmx21RSVEd+nJd24zhowMSC7MR74OWE?= =?us-ascii?Q?CVHsKjHwiCNWayPmZJqxn8t3e+SCwJLDAvDlvaVqX4RIrThBEvwBbRA6oc0u?= =?us-ascii?Q?EutUAhLlnJ6xH746/aF7WeM5CSQwsRZXSLY1Mm+oZ+cKUgf4WNsGD2TcVWRw?= =?us-ascii?Q?tzK2WnZNA4hzYfeSStgS+OVRDInjz6FQssDWG4yYJ0jURFPPgc4Rf4eEukq9?= =?us-ascii?Q?M3sWLFVltoTRUQf6XoaFfJgK6pXRuG8LY8LEmNkKxb2DiAqM/2s4UFikv08S?= =?us-ascii?Q?KWkhiLdtXyGKo5ojgYKwTPNYtJfNHwt3VHlY8Ic/9pjdrm5GSTE5xwmogtfu?= =?us-ascii?Q?0EFeN7OV7Fv6I+D4jDfZTqwLDdrpsa2DUVzd1iHWzd2nrog84+NZHtruPm0P?= =?us-ascii?Q?EiTB0GcK/6KIfh57BIqXHszuhESYnt4tPaVy7Gz63Qvyls3fDWVV8OlhqFIs?= =?us-ascii?Q?655RbjqMKcZu1eeKC77nd0Y8pr3NkomgsVcrDQMCTu8sjCpSMEMfc+XRQ1Zo?= =?us-ascii?Q?nbQGhoBJZc1URDIOtkmBEiHDsKP+4V0thELMjkcAuppwvq1ZkwXT4xod5H+d?= =?us-ascii?Q?GNbOL8a1IlSygXockuSZsvMsU/ZO/OOBFYumRc+otOd6Egkl?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 18a99d26-03ad-4bf5-7614-08df1b11baa5 X-MS-Exchange-CrossTenant-AuthSource: DM4PR12MB6374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Sep 2026 14:31:47.2637 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ap8i9Kr6FVhPCLgcA/yM5w1sXsAXGl6sbGR5GZZ6fp4/srlbRibHmzlztEOnT9lIzHEe4AxiJLgw365c9PvtWg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB8615 On Fri, Sep 25, 2026 at 11:09:18AM +0800, Rui Qi wrote: > When erst_get_record_id_begin() returns an error, get_saved_records() > jumps to the out_end label and unconditionally calls > erst_get_record_id_end(). But begin() only bumps the > erst_record_id_cache refcount on success, so calling end() after a > failed begin() underflows it. > > This is reachable when fmpm is built as a module: if the cache lock > is contended (by pstore, erst-dbg, or apei_read_mce) and a signal > arrives, mutex_lock_interruptible() in begin() returns -EINTR without > incrementing the refcount. end() then takes the lock, decrements the > refcount below zero, and BUG_ON() fires while still holding it. The > loader dies with the mutex held, so every later ERST user blocks > indefinitely. > > Built-in fmpm is not affected, since its initcall runs before > userspace and mutex_lock_interruptible() can never see a signal. > > Fix it by jumping to the out label on begin() failure, skipping > erst_get_record_id_end(). kfree(old) moves to that shared label so > it still runs on every path. > > Fixes: 6f15e617cc99 ("RAS: Introduce a FRU memory poison manager") > Signed-off-by: Rui Qi > --- > Changes in v3: > - Reword the commit message per review feedback from Yazen Ghannam. > - No code changes. > > Patches 1-3 of the series are unchanged and already carry Reviewed-by > on v2; they are not resent. > > Link: https://lore.kernel.org/r/20260924161746.GI1080284@yaz-khff2.amd.com > > drivers/ras/amd/fmpm.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/ras/amd/fmpm.c b/drivers/ras/amd/fmpm.c > index c13db1f743e5..48a437042953 100644 > --- a/drivers/ras/amd/fmpm.c > +++ b/drivers/ras/amd/fmpm.c > @@ -673,7 +673,7 @@ static int get_saved_records(void) > > ret = erst_get_record_id_begin(&pos); > if (ret < 0) > - goto out_end; > + goto out; > > while (!erst_get_record_id_next(&pos, &record_id)) { > if (record_id == APEI_ERST_INVALID_RECORD_ID) > @@ -714,8 +714,8 @@ static int get_saved_records(void) > > out_end: > erst_get_record_id_end(); > - kfree(old); > out: > + kfree(old); > return ret; > } > > -- Looks good to me. Reviewed-by: Yazen Ghannam Thanks, Yazen