** Package changed: ubuntu => nfs-utils (Ubuntu) ** Tags added: jammy
-- You received this bug notification because you are a member of Debcrafters packages, which is subscribed to nfs-utils in Ubuntu. https://bugs.launchpad.net/bugs/2111213 Title: System hang due refcount_t underflow issue and VFS: Close: file count is 0 Status in nfs-utils package in Ubuntu: New Bug description: ================ Environment details: ================ - Linux Kernel Version: 5.15.0-117 - Ubuntu 22.04 - nfs-utils package: 1:1.3.4-2.5ubuntu3.3 and 1:2.6.1-1ubuntu1.2 - Using NFSv3 ================ Issue observed: ================ - I see `refcount_t underflow` and `use-after-free` warnings associated specifically with `nfsd_write` operations in the syslogs. - After this occurs, the system eventually becomes non-functional, requiring a manual reboot. - The last NFS-related operation seems to be an `unexport` of a filesystem: exportfs -u 10.20.30.40:/fs/4d148fdf-6b18-48c8-8215-7c5dd58cac7d/c0 - After the problem occurs, syslogs flood continuously with these repetitive and only entries: VFS: Close: file count is 0 - On the system console, I consistently notice one `exportfs` process stuck in a CPU soft lockup—this persists until the system gets rebooted. ================ Stack trace ================ 2025-05-15T10:22:24.988837+00:00 <4> kernel - [7144513.654935] ------------[ cut here ]------------ 2025-05-15T10:22:24.989181+00:00 <4> kernel - [7144513.654941] refcount_t: underflow; use-after-free. 2025-05-15T10:22:24.989186+00:00 <4> kernel - [7144513.654963] WARNING: CPU: 71 PID: 2010514 at lib/refcount.c:28 refcount_warn_saturate+0xf7/0x150 ... ... 2025-05-15T10:22:24.989221+00:00 <4> kernel - [7144513.655146] RIP: 0010:refcount_warn_saturate+0xf7/0x150 2025-05-15T10:22:24.989229+00:00 <4> kernel - [7144513.655149] Code: eb 9e 0f b6 1d 12 2b b9 01 80 fb 01 0f 87 10 92 6f 00 83 e3 01 75 89 48 c7 c7 30 10 e4 8e c6 05 f6 2a b9 01 01 e8 b3 0b 6c 00 <0f> 0b e9 6f ff ff ff 0f b6 1d e1 2a b9 01 80 fb 01 0f 87 cd 91 6f 2025-05-15T10:22:24.989231+00:00 <4> kernel - [7144513.655153] RSP: 0018:ff297e72f41e7d48 EFLAGS: 00010286 2025-05-15T10:22:24.989232+00:00 <4> kernel - [7144513.655156] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000027 2025-05-15T10:22:24.989233+00:00 <4> kernel - [7144513.655158] RDX: ff249fc37fae0588 RSI: 0000000000000001 RDI: ff249fc37fae0580 2025-05-15T10:22:24.989234+00:00 <4> kernel - [7144513.655160] RBP: ff297e72f41e7d50 R08: 0000000000000003 R09: fffffffffff6bb28 2025-05-15T10:22:24.989235+00:00 <4> kernel - [7144513.655162] R10: ff249fc37f16bb30 R11: 0000000000000001 R12: ff249fb2124ba380 2025-05-15T10:22:24.989239+00:00 <4> kernel - [7144513.655164] R13: ff249fb2124ba3b8 R14: 00000000000000e5 R15: ff249f4589a40000 2025-05-15T10:22:24.989240+00:00 <4> kernel - [7144513.655166] FS: 0000000000000000(0000) GS:ff249fc37fac0000(0000) knlGS:0000000000000000 2025-05-15T10:22:24.989241+00:00 <4> kernel - [7144513.655169] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 2025-05-15T10:22:24.989242+00:00 <4> kernel - [7144513.655171] CR2: 00007f02a7291000 CR3: 000000413b00e006 CR4: 0000000000771ee0 2025-05-15T10:22:24.989243+00:00 <4> kernel - [7144513.655173] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 2025-05-15T10:22:24.989244+00:00 <4> kernel - [7144513.655175] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 2025-05-15T10:22:24.989247+00:00 <4> kernel - [7144513.655177] PKRU: 55555554 2025-05-15T10:22:24.989248+00:00 <4> kernel - [7144513.655178] Call Trace: 2025-05-15T10:22:24.989248+00:00 <4> kernel - [7144513.655181] <TASK> 2025-05-15T10:22:24.989249+00:00 <4> kernel - [7144513.655185] ? show_trace_log_lvl+0x1d6/0x2ea 2025-05-15T10:22:24.989250+00:00 <4> kernel - [7144513.655193] ? show_trace_log_lvl+0x1d6/0x2ea 2025-05-15T10:22:24.989251+00:00 <4> kernel - [7144513.655197] ? nfsd_file_put+0x10f/0x170 [nfsd] 2025-05-15T10:22:24.989251+00:00 <4> kernel - [7144513.655255] ? show_regs.part.0+0x23/0x29 2025-05-15T10:22:24.989255+00:00 <4> kernel - [7144513.655258] ? show_regs.cold+0x8/0xd 2025-05-15T10:22:24.989255+00:00 <4> kernel - [7144513.655260] ? refcount_warn_saturate+0xf7/0x150 2025-05-15T10:22:24.989256+00:00 <4> kernel - [7144513.655263] ? __warn+0x8c/0x100 2025-05-15T10:22:24.989257+00:00 <4> kernel - [7144513.655268] ? refcount_warn_saturate+0xf7/0x150 2025-05-15T10:22:24.989257+00:00 <4> kernel - [7144513.655270] ? report_bug+0xa4/0xd0 2025-05-15T10:22:24.989258+00:00 <4> kernel - [7144513.655275] ? handle_bug+0x39/0x90 2025-05-15T10:22:24.989261+00:00 <4> kernel - [7144513.655279] ? exc_invalid_op+0x19/0x70 2025-05-15T10:22:24.989262+00:00 <4> kernel - [7144513.655281] ? asm_exc_invalid_op+0x1b/0x20 2025-05-15T10:22:24.989262+00:00 <4> kernel - [7144513.655287] ? refcount_warn_saturate+0xf7/0x150 2025-05-15T10:22:24.989263+00:00 <4> kernel - [7144513.655290] ? refcount_warn_saturate+0xf7/0x150 2025-05-15T10:22:24.989264+00:00 <4> kernel - [7144513.655292] nfsd_file_put+0x10f/0x170 [nfsd] 2025-05-15T10:22:24.989265+00:00 <4> kernel - [7144513.655326] nfsd_write+0x8a/0x140 [nfsd] 2025-05-15T10:22:24.989267+00:00 <4> kernel - [7144513.655361] nfsd3_proc_write+0xe0/0x170 [nfsd] 2025-05-15T10:22:24.989268+00:00 <4> kernel - [7144513.655395] nfsd_dispatch+0x173/0x270 [nfsd] 2025-05-15T10:22:24.989268+00:00 <4> kernel - [7144513.655427] svc_process_common+0x3d7/0x720 [sunrpc] 2025-05-15T10:22:24.989269+00:00 <4> kernel - [7144513.655484] ? nfsd_svc+0x200/0x200 [nfsd] 2025-05-15T10:22:24.989270+00:00 <4> kernel - [7144513.655518] svc_process+0xbc/0x100 [sunrpc] 2025-05-15T10:22:24.989270+00:00 <4> kernel - [7144513.655561] nfsd+0xd3/0x100 [nfsd] 2025-05-15T10:22:24.989271+00:00 <4> kernel - [7144513.655590] ? trace_event_raw_event_nfsd_export_update+0x190/0x190 [nfsd] 2025-05-15T10:22:24.989272+00:00 <4> kernel - [7144513.655619] kthread+0x127/0x150 2025-05-15T10:22:24.989273+00:00 <4> kernel - [7144513.655624] ? set_kthread_struct+0x50/0x50 2025-05-15T10:22:24.989274+00:00 <4> kernel - [7144513.655628] ret_from_fork+0x1f/0x30 2025-05-15T10:22:24.989275+00:00 <4> kernel - [7144513.655636] </TASK> 2025-05-15T10:22:24.989276+00:00 <4> kernel - [7144513.655637] ---[ end trace 2c2d196f39b3f573 ]--- 2025-05-15T10:22:25.000964+00:00 <3> kernel - [7144513.668313] VFS: Close: file count is 0 2025-05-15T10:22:25.000984+00:00 <3> kernel - [7144513.668317] VFS: Close: file count is 0 2025-05-15T10:22:25.000986+00:00 <3> kernel - [7144513.668318] VFS: Close: file count is 0 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/2111213/+subscriptions -- Mailing list: https://launchpad.net/~debcrafters-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~debcrafters-packages More help : https://help.launchpad.net/ListHelp
