XPost: linux.debian.bugs.dist, linux.kernel
From: TWR@tylerwross.com
On Friday, November 14th, 2025 at 7:19 AM, Chuck Lever wrote:
> Then I would say further hunting for the broken commit is going to be
> fruitless. Adding the WARNs in net/sunrpc/xdr.c is a good next step so
> we see which XDR data item (assuming it's the same one every time) is
> failing to decode.
I added WARNs after each trace_rpc_xdr_overflow() call, and then a couple
pr_info() inside xdr_copy_to_scratch() as a follow-up.
If I'm understanding correctly, it's failing in the xdr_copy_to_scratch()
call inside xdr_inline_decode(), because the xdr_stream struct has an
unset/NULL scratch kvec. I don't understand the context enough to
speculate on why, though.
[ 26.844102] Entered xdr_copy_to_scratch()
[ 26.844105] xdr->scratch.iov_base: 0000000000000000
[ 26.844107] xdr->scratch.iov_len: 0
[ 26.844127] ------------[ cut here ]------------
[ 26.844128] WARNING: CPU: 1 PID: 886 at net/sunrpc/xdr.c:1490
xdr_inline_decode.cold+0x65/0x141 [sunrpc]
[ 26.844153] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs lockd
grace netfs binfmt_misc intel_rapl_msr intel_rapl_common kvm_amd ccp kvm
cfg80211 hid_generic usbhid hid irqbypass rfkill ghash_clmulni_intel
aesni_intel pcspkr 8021q garp stp
virtio_balloon llc mrp button evdev joydev sg auth_rpcgss sunrpc configfs
efi_pstore nfnetlink vsock_loopback vmw_vsock_virtio_transport_common
vmw_vsock_vmci_transport vsock vmw_vmci qemu_fw_cfg ip_tables x_tables autofs4
ext4 crc16 mbcache jbd2 crc32c_
cryptoapi sr_mod cdrom bochs uhci_hcd drm_client_lib drm_shmem_helper ehci_pci
ata_generic sd_mod drm_kms_helper ehci_hcd ata_piix libata drm virtio_net
usbcore virtio_scsi floppy psmouse net_failover failover scsi_mod serio_raw
i2c_piix4 usb_common scsi_
common i2c_smbus
[ 26.844217] CPU: 1 UID: 591200003 PID: 886 Comm: ls Not tainted
6.17.8-debbug1120598hack3 #9 PREEMPT(lazy)
[ 26.844220] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 26.844222] RIP: 0010:xdr_inline_decode.cold+0x65/0x141 [sunrpc]
[ 26.844238] Code: 24 48 c7 c7 e7 eb 8c c0 48 8b 71 28 e8 5a 36 fc d7 48 8b
0c 24 4c 8b 44 24 10 48 8b 54 24 08 4c 39 41 28 73 0c 0f 1f 44 00 00 <0f> 0b
e9 b7 fe fe ff 48 89 d8 48 89 cf 4c 89 44 24 08 48 29 d0 48
[ 26.844240] RSP: 0018:ffffd09e82ce3758 EFLAGS: 00010293
[ 26.844242] RAX: 0000000000000017 RBX: ffff8f1e0adcffe8 RCX:
fffd09e82ce3838
[ 26.844244] RDX: ffff8f1e0adcffe4 RSI: 0000000000000001 RDI:
fff8f1f37c5ce40
[ 26.844245] RBP: ffffd09e82ce37b4 R08: 0000000000000008 R09:
fffd09e82ce3600
[ 26.844246] R10: ffffffff9acdb348 R11: 00000000ffffefff R12:
00000000000001a
[ 26.844247] R13: ffff8f1e01151200 R14: 0000000000000000 R15:
000000000440000
[ 26.844250] FS: 00007fa5d13db240(0000) GS:ffff8f1f9c44a000(0000)
knlGS:0000000000000000
[ 26.844252] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 26.844253] CR2: 00007fa5d13b9000 CR3: 000000010ab82000 CR4:
000000000750ef0
[ 26.844255] PKRU: 55555554
[ 26.844257] Call Trace:
[ 26.844259]
[ 26.844263] __decode_op_hdr+0x20/0x120 [nfsv4]
[ 26.844288] nfs4_xdr_dec_readdir+0xbb/0x120 [nfsv4]
[ 26.844305] gss_unwrap_resp+0x9e/0x150 [auth_rpcgss]
[ 26.844311] call_decode+0x211/0x230 [sunrpc]
[ 26.844332] ? __pfx_call_decode+0x10/0x10 [sunrpc]
[ 26.844348] __rpc_execute+0xb6/0x480 [sunrpc]
[ 26.844369] ? rpc_new_task+0x17a/0x200 [sunrpc]
[ 26.844386] rpc_execute+0x133/0x160 [sunrpc]
[ 26.844401] rpc_run_task+0x103/0x160 [sunrpc]
[ 26.844419] nfs4_call_sync_sequence+0x74/0xb0 [nfsv4]
[ 26.844440] _nfs4_proc_readdir+0x28d/0x310 [nfsv4]
[ 26.844459] nfs4_proc_readdir+0x60/0xf0 [nfsv4]
[ 26.844475] nfs_readdir_xdr_to_array+0x1fb/0x410 [nfs]
[ 26.844494] nfs_readdir+0x2ed/0xf00 [nfs]
[ 26.844506] iterate_dir+0xaa/0x270
[ 26.844517] ? srso_alias_return_thunk+0x5/0xfbef5
[ 26.844521] __x64_sys_getdents64+0x7b/0x110
[ 26.844523] ? __pfx_filldir64+0x10/0x10
[ 26.844526] do_syscall_64+0x82/0x320
[ 26.844530] ? mod_memcg_lruvec_state+0xe7/0x2e0
[ 26.844533] ? srso_alias_return_thunk+0x5/0xfbef5
[ 26.844535] ? srso_alias_return_thunk+0x5/0xfbef5
[ 26.844537] ? __lruvec_stat_mod_folio+0x85/0xd0
[ 26.844539] ? srso_alias_return_thunk+0x5/0xfbef5
[ 26.844541] ? srso_alias_return_thunk+0x5/0xfbef5
[ 26.844550] ? set_ptes.isra.0+0x36/0x80
[ 26.844555] ? srso_alias_return_thunk+0x5/0xfbef5
[ 26.844557] ? srso_alias_return_thunk+0x5/0xfbef5
[ 26.844560] ? do_anonymous_page+0x101/0x970
[continued in next message]
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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