Hello Nicolin, Hope you are doing well. I am Chaitanya from the linux graphics team in Intel.
This mail is regarding a regression we are seeing in our CI runs[1] on linux-next repository. Since the version next-20250321 [2], we are seeing the following regression ````````````````````````````````````````````````````````````````````````````````` <4>[ 0.226495] Unpatched return thunk in use. This should not happen! <4>[ 0.226502] WARNING: CPU: 0 PID: 1 at arch/x86/kernel/cpu/bugs.c:3107 __warn_thunk+0x62/0x70 <4>[ 0.226513] Modules linked in: <4>[ 0.226521] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc7-next-20250321-next-20250321-g9388ec571cb1+ #1 PREEMPT(voluntary) <4>[ 0.226532] Hardware name: ASUS System Product Name/PRIME Z790-P WIFI, BIOS 0812 02/24/2023 <4>[ 0.226539] RIP: 0010:__warn_thunk+0x62/0x70 <4>[ 0.226544] Code: 34 4c 5d 02 01 e8 fe f6 a7 00 84 c0 75 d9 48 c7 c7 f8 bf 0d 83 e8 7e c6 08 00 48 c7 c7 a0 a2 a0 82 e8 e2 f6 a7 00 84 c0 75 bd <0f> 0b eb b9 cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 <4>[ 0.226559] RSP: 0000:ffffc90000067d78 EFLAGS: 00010246 <4>[ 0.226565] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 <4>[ 0.226571] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 <4>[ 0.226577] RBP: ffffc90000067d80 R08: 0000000000000000 R09: 0000000000000000 <4>[ 0.226583] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 <4>[ 0.226589] R13: ffffffff83c9417c R14: ffff88887f344bc0 R15: ffff888102370100 <4>[ 0.226595] FS: 0000000000000000(0000) GS:ffff8888dacfd000(0000) knlGS:0000000000000000 <4>[ 0.226602] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4>[ 0.226608] CR2: ffff88887f7ff000 CR3: 000000000344a000 CR4: 0000000000f50ef0 <4>[ 0.226614] PKRU: 55555554 <4>[ 0.226617] Call Trace: <4>[ 0.226620] <TASK> <4>[ 0.226624] ? show_regs+0x6c/0x80 <4>[ 0.226630] ? __warn+0x94/0x210 <4>[ 0.226635] ? __warn_thunk+0x62/0x70 <4>[ 0.226640] ? __report_bug+0x110/0x280 <4>[ 0.227000] ? __lock_acquire+0x447/0x2c70 <4>[ 0.227011] ? _prb_read_valid+0x25a/0x310 <4>[ 0.227018] ? __lock_acquire+0x447/0x2c70 <4>[ 0.227024] ? prb_read_valid+0x1c/0x30 <4>[ 0.227037] ? lock_acquire+0xc4/0x330 <4>[ 0.227055] ? _prb_read_valid+0x25a/0x310 <4>[ 0.227073] ? __warn_thunk+0x62/0x70 <4>[ 0.227081] ? report_bug+0x24/0x80 <4>[ 0.227089] ? handle_bug+0x16a/0x2a0 <4>[ 0.227098] ? exc_invalid_op+0x18/0x80 <4>[ 0.227106] ? asm_exc_invalid_op+0x1b/0x20 <4>[ 0.227122] ? __warn_thunk+0x62/0x70 <4>[ 0.227130] ? __warn_thunk+0x5e/0x70 <4>[ 0.227135] ? iommu_dma_ranges_sort+0x40/0x40 <4>[ 0.227144] warn_thunk_thunk+0x16/0x30 <4>[ 0.227157] do_one_initcall+0x5d/0x460 <4>[ 0.227171] kernel_init_freeable+0x3ac/0x530 <4>[ 0.227187] ? __pfx_kernel_init+0x10/0x10 <4>[ 0.227196] kernel_init+0x1b/0x200 <4>[ 0.227203] ret_from_fork+0x44/0x70 <4>[ 0.227210] ? __pfx_kernel_init+0x10/0x10 <4>[ 0.227217] ret_from_fork_asm+0x1a/0x30 <4>[ 0.227236] </TASK> ````````````````````````````````````````````````````````````````````````````````` Details log can be found in [3]. After bisecting the tree, the following patch [4] seems to be the first "bad" commit ````````````````````````````````````````````````````````````````````````````````````````````````````````` commit e009e088d88e8402539f9595b10c0014125a70c1 Author: Nicolin Chen mailto:[email protected] Date: Thu Mar 6 13:00:49 2025 -0800 iommu: Drop sw_msi from iommu_domain There are only two sw_msi implementations in the entire system, thus it's not very necessary to have an sw_msi pointer. Instead, check domain->cookie_type to call the two sw_msi implementations directly from the core code. ````````````````````````````````````````````````````````````````````````````````````````````````````````` We also verified that if we revert the patch the issue is not seen. Could you please check why the patch causes this regression and provide a fix if necessary? Thank you. Regards Chaitanya [1] https://intel-gfx-ci.01.org/tree/linux-next/combined-alt.html? [2] https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20250321 [3] https://intel-gfx-ci.01.org/tree/linux-next/next-20250321/bat-rpls-4/boot0.txt [4] https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20250321&id=e009e088d88e8402539f9595b10c0014125a70c1
