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Mon, 28 Oct 2024 22:57:57 +0000 Date: Mon, 28 Oct 2024 15:57:55 -0700 From: Dan Williams To: Thorsten Leemhuis , Dan Williams , CC: , , , Subject: Re: [PATCH v2] driver core: Fix userspace expectations of uevent_show() as a probe barrier Message-ID: <672016f35ed5d_bc69d2946a@dwillia2-xfh.jf.intel.com.notmuch> References: <172790598832.1168608.4519484276671503678.stgit@dwillia2-xfh.jf.intel.com> <67047c516045d_964fe294b1@dwillia2-xfh.jf.intel.com.notmuch> <42dfef93-eb8a-458b-b76b-b7de9077d0af@leemhuis.info> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <42dfef93-eb8a-458b-b76b-b7de9077d0af@leemhuis.info> X-ClientProxiedBy: MW2PR16CA0009.namprd16.prod.outlook.com (2603:10b6:907::22) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) 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: PH8PR11MB8107:EE_|LV8PR11MB8608:EE_ X-MS-Office365-Filtering-Correlation-Id: c372772c-6129-4db3-c324-08dcf7a3f70e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?TOeUoh5/uarTvqYj0xXg9s7mUJ4yR7364SXVw8s+sChVz7esOPMi5ngtt1CQ?= =?us-ascii?Q?3dwLK/NWtlfnlon3XLWLGcCaNd5AMV4CjDikOyo/T/M0Xr4Ofz6mYqXySGtE?= =?us-ascii?Q?EmgliHkeIdO7LFsljZpri8L95494QNIP+LfrBDFFuKlyP06XSFCE1kswUixM?= =?us-ascii?Q?8bQCFhic6RdfqpePZCKjjqc/ocAk+ctWQ83JM83Uei98TtQMPC7lJiNomq/o?= =?us-ascii?Q?oKq16UDy8QddMP2fD1FJTAu/QZAHA1yF8U1fSgpgqDjbKj1ZBFuJkIUC1Fu2?= =?us-ascii?Q?lt0+62nHFenDpFMscBqS7WcXKDOr9hpoItX8mWaY68sANJ/pA3JPfmPVCZdr?= =?us-ascii?Q?HKJ859QpVpZddswIun0p8xo5fbyAA91CrnsK5+vbWRpouXpeBm/X2wmuXYFj?= =?us-ascii?Q?H3gE18yJB0uyP9o5fypbfaePpIWf43Zs67E7E1+piYEQuA3LFEnclT7IErMQ?= =?us-ascii?Q?i9rk2Of+4NOE0V2b8J6Cr5arkTQfh6uwEvvENRwsr7mY956ydUEvE9HAuhtW?= =?us-ascii?Q?knO7mMLojQug5Z4w7aKcF8z9P4QN9foHp5gm6Ewo+P4KmvfaGSstfTl/GCLV?= =?us-ascii?Q?1msj6VFbf6dZwGrtNCBKEQReDLVB1cWfISS89DKqCQMBpTpHnYYj+/4s1pCv?= =?us-ascii?Q?H0AuVshThutXpCaKjtXKutkGVMNdtwsqxJ2CltJVR03q7JeZlDWpIyjvnOHa?= =?us-ascii?Q?JHdB7TUT+DckloHiGhNatUKa21mlOwqdLEqaDwBrTjTro3M0Ec6niQPx8Mh3?= =?us-ascii?Q?e0jsHaYCD8OkXtg1rV6u21q8eiyaU3yK7peLlCQJAD9F4JVYIGrY8e8plOU3?= =?us-ascii?Q?aRXnAG7gll3Qnrquac7tN4ddM4I3Xms2f9A0aP7sbztT/cxUk8bZ42vA6yyX?= =?us-ascii?Q?6TOaYe2OYrt2P1MjIhVxrQ5nE7cVNk4ibiEwuLBIppX3tFIziXrLj/4Vf4kT?= =?us-ascii?Q?GCDcvLroOmHrd0yHZXeKsEuLp9zj6Tf/hb0eyxEqluBY+TP4q5g/1HGuzfv1?= =?us-ascii?Q?U10P54xmWU8EGY71E7rswPsmlduncHWkNG1m7jXjC7s0jevlloPg1Xc2/ISm?= =?us-ascii?Q?cZjB4XaYmsk6WydDIS2frFVuqtKaG2GJsmnWfTfMLvtmvf8moGUuxxQ5bblb?= =?us-ascii?Q?IK2C1qSGTwdi6Y1y06jKgRFuiZvpv9Umtk902xks4E5JwbGAxGEkgCaw266b?= =?us-ascii?Q?8yt9YvySXdQw3Fb+ntoWA6X+ohVKaIbOiQZjf3xZq++PncQMdiB8S89O6Ovd?= =?us-ascii?Q?052q/u8fg1dK827aG+3rdJPAMF29jkpJwYX1wl8A79xI17FVnbSkLQE8P7By?= =?us-ascii?Q?ZU8R+Hy0OIteaq89Ahs3WSDAn1NOVqf55V1ySdD+qf8xQokCJZZzz19LwMOc?= =?us-ascii?Q?yElqITeAcU0acOdAJRWwN/IpA0wCr1r0gEiEpXS8MtibgiD7lpRibR49UbNP?= =?us-ascii?Q?FNCOZMEuIoSu/gfCALoz2lQGwxTrnXx7kUnAxOP5pzVFpLEesXZbOfUSjPQQ?= =?us-ascii?Q?3WMiC+UYUvo2/cboWBVpsEuzb35pdhMOcygvjldDdcbB17XsAE5okW0XJuYz?= =?us-ascii?Q?FYijC06CRmNguBft/wn5ysUzI7oYluS9xqyGx8THaMN3hpQt70FhfzU+MuCD?= =?us-ascii?Q?vA=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: c372772c-6129-4db3-c324-08dcf7a3f70e X-MS-Exchange-CrossTenant-AuthSource: PH8PR11MB8107.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Oct 2024 22:57:57.8074 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 2fgMxDue5/d8V28yIXaJ9xbBBCdUUSxYMlEHJxh0fn7k84LpZ0sRM5aN10AHbFoT9+F8yZ643m8RvtvCzTbkpIqYbIqP+mcFtR8yewB35E0= X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV8PR11MB8608 X-OriginatorOrg: intel.com Thorsten Leemhuis wrote: > On 08.10.24 02:26, Dan Williams wrote: > > Dan Williams wrote: > >> Changes since v1 [1]: > >> - Move the new "locked" infrastructure to private header files to make > >> it clear it is not approved for general usage (Greg) > > > > Greg, per the 0day report and further testing I am missing something > > subtle in using kernfs open files to pin device objects. So hold off on > > this for now until I can get that root caused. If someone else can spot > > what I missed feel free to chime in, but otherwise I will circle back. > > > > If I don't get back to this before -rc6 I think the theoretical deadlock > > that would be re-introduced by a revert of 15fffc6a5624 would be > > preferable to this reported regression. I am not aware of any reports of > > that deadlock triggering in practice. > Was there any progress? If not: given that Linus prefers to have things > fixed by -rc6 I wonder if now would be a good time to get the revert on > track for a merge later this week. Revert 15fffc6a5624 ("driver core: Fix uevent_show() vs driver detach race"), which reintroduces a theoretical lockdep splat, is my preference at this point. Even if I had a new version of this replacement patch in hand today I would still want it to be v6.13 material, not v6.12-rc. It deserves a full kernel cycle soak time to shake out issues before release.