On 2026/9/18 05:20, [email protected] wrote: > On Thu, 2026-09-10 at 16:06 +0800, Peiyang He wrote: >> nouveau_bo_pin_locked() checks whether an already pinned BO is in a >> memory domain compatible with a new pin request. When the domains are >> incompatible, it sets -EBUSY but still calls ttm_bo_pin() before >> returning. >> >> Callers treat a failed nouveau_bo_pin() as not having acquired a new >> pin, >> so the extra pin count is never decreased by a matching unpin. >> This triggers the warning in ttm_bo_release(): >> >> WARN_ON_ONCE(bo->pin_count); >> >> Found when fuzzing the nouveau driver with a modified Syzkaller: >> >> WARNING: drivers/gpu/drm/ttm/ttm_bo.c:256 at >> ttm_bo_release+0x827/0x9e0 drivers/gpu/drm/ttm/ttm_bo.c:256, CPU#1: >> syz.3.24/2212 >> Modules linked in: >> CPU: 1 UID: 0 PID: 2212 Comm: syz.3.24 Not tainted 7.2.0 #24 >> PREEMPT(lazy) >> nouveau 0000:01:00.0: gsp:msg fn:103 len:0x40/0x20 res:0x19 >> resp:0x19 >> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS >> 1.16.3-debian-1.16.3-2 04/01/2014 >> RIP: 0010:ttm_bo_release+0x827/0x9e0 >> drivers/gpu/drm/ttm/ttm_bo.c:256 >> Code: 02 00 0f 85 51 01 00 00 48 8b 7b 08 e8 d2 20 01 00 e9 >> 80 fd ff ff e8 d8 15 c0 fe 90 0f 0b 90 e9 e1 f8 ff ff e8 ca 15 c0 fe >> 90 <0f> 0b 90 e9 a4 f8 ff ff e8 bc 15 c0 fe be 03 00 00 00 4c 89 e7 >> e8 >> msg: 00000000: 05 00 d0 c1 04 00 f0 f1 01 30 00 00 2d 90 00 >> 00 .........0..-... >> RSP: 0018:ffffc9000f5cf710 EFLAGS: 00010293 >> RAX: 0000000000000000 RBX: ffff888018e5d2a8 RCX: >> ffffffff82bb1b36 >> RDX: ffff888017b68000 RSI: 0000000000000004 RDI: >> ffff888018e5d2a8 >> msg: 00000010: 19 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> 00 ................ >> RBP: ffff88801261c720 R08: 0000000000000001 R09: >> ffffed10031cba55 >> R10: ffff888018e5d2ab R11: 00000000000000f3 R12: >> ffff888018e5d290 >> R13: ffff888018e5d2d4 R14: ffff88801b219c18 R15: >> dffffc0000000000 >> FS: 0000000000000000(0000) GS:ffff8880e0f6f000(0000) >> knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 0000001b31223ffc CR3: 0000000028e00005 CR4: >> 0000000000770ef0 >> PKRU: 80000000 >> Call Trace: >> <TASK> >> kref_put include/linux/kref.h:65 [inline] >> ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:325 [inline] >> ttm_bo_fini+0x55/0x80 drivers/gpu/drm/ttm/ttm_bo.c:330 >> nouveau_gem_object_del+0xb2/0x1b0 >> drivers/gpu/drm/nouveau/nouveau_gem.c:90 >> drm_gem_object_free+0x5f/0x90 drivers/gpu/drm/drm_gem.c:1165 >> kref_put include/linux/kref.h:65 [inline] >> __drm_gem_object_put include/drm/drm_gem.h:562 [inline] >> drm_gem_object_put include/drm/drm_gem.h:575 [inline] >> nouveau_abi16_chan_fini.constprop.0+0x44f/0x5a0 >> drivers/gpu/drm/nouveau/nouveau_abi16.c:195 >> nouveau 0000:01:00.0: syz.2.23[2209]: Unknown handle >> 0x00000000 >> nouveau_abi16_fini+0x1d0/0x340 >> drivers/gpu/drm/nouveau/nouveau_abi16.c:225 >> nouveau_drm_postclose+0x18b/0x3e0 >> drivers/gpu/drm/nouveau/nouveau_drm.c:1284 >> nouveau 0000:01:00.0: syz.2.23[2209]: validate_init >> drm_file_free.part.0+0x6d6/0xb60 >> drivers/gpu/drm/drm_file.c:267 >> drm_file_free drivers/gpu/drm/drm_file.c:237 [inline] >> drm_close_helper.isra.0+0x11a/0x160 >> drivers/gpu/drm/drm_file.c:290 >> drm_release+0x1ab/0x330 drivers/gpu/drm/drm_file.c:438 >> __fput+0x39c/0xa60 fs/file_table.c:512 >> nouveau 0000:01:00.0: syz.2.23[2209]: validate: -2 >> task_work_run+0x15a/0x230 kernel/task_work.c:233 >> exit_task_work include/linux/task_work.h:40 [inline] >> do_exit+0x82b/0x25a0 kernel/exit.c:1009 >> do_group_exit+0xc2/0x280 kernel/exit.c:1152 >> get_signal+0x1d6e/0x1f30 kernel/signal.c:3046 >> arch_do_signal_or_restart+0x7d/0x6e0 >> arch/x86/kernel/signal.c:337 >> __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] >> exit_to_user_mode_loop+0xdf/0x440 kernel/entry/common.c:101 >> __exit_to_user_mode_prepare include/linux/irq-entry- >> common.h:207 [inline] >> syscall_exit_to_user_mode_prepare include/linux/irq-entry- >> common.h:230 [inline] >> syscall_exit_to_user_mode include/linux/entry-common.h:318 >> [inline] >> do_syscall_64+0x4f8/0x690 arch/x86/entry/syscall_64.c:100 >> entry_SYSCALL_64_after_hwframe+0x77/0x7f >> RIP: 0033:0x7f12bac8594d >> Code: Unable to access opcode bytes at 0x7f12bac85923. >> RSP: 002b:00007f12b96e70d8 EFLAGS: 00000246 ORIG_RAX: >> 00000000000000ca >> RAX: 0000000000000001 RBX: 00007f12baf15fa8 RCX: >> 00007f12bac8594d >> RDX: 00000000000f4240 RSI: 0000000000000081 RDI: >> 00007f12baf15fac >> RBP: 00007f12baf15fa0 R08: 00007f12baee8000 R09: >> 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000246 R12: >> 0000000000000000 >> R13: 00007f12baf16038 R14: 0000000000000006 R15: >> 00007ffe2ed394b0 >> </TASK> >> irq event stamp: 47867 >> hardirqs last enabled at (47883): [<ffffffff815cafc6>] >> __up_console_sem+0x66/0x70 kernel/printk/printk.c:347 >> hardirqs last disabled at (47892): [<ffffffff815cafab>] >> __up_console_sem+0x4b/0x70 kernel/printk/printk.c:345 >> softirqs last enabled at (47880): [<ffffffff81434277>] >> __do_softirq kernel/softirq.c:656 [inline] >> softirqs last enabled at (47880): [<ffffffff81434277>] >> invoke_softirq kernel/softirq.c:496 [inline] >> softirqs last enabled at (47880): [<ffffffff81434277>] >> __irq_exit_rcu+0x137/0x1c0 kernel/softirq.c:735 >> softirqs last disabled at (47875): [<ffffffff81434277>] >> __do_softirq kernel/softirq.c:656 [inline] >> softirqs last disabled at (47875): [<ffffffff81434277>] >> invoke_softirq kernel/softirq.c:496 [inline] >> softirqs last disabled at (47875): [<ffffffff81434277>] >> __irq_exit_rcu+0x137/0x1c0 kernel/softirq.c:735 >> >> Fix by going to the out path as soon as the incompatible placement >> is detected. This matches the correct bahaviour in other DRM drivers >> such as amdgpu_bo_pin() in amdgpu. >> >> Cc: [email protected] >> Fixes: ad76b3f7c7a0 ("drm/nouveau: teach nouveau_bo_pin() how to >> force a contig vram allocation") >> Signed-off-by: Peiyang He <[email protected]> >> Assisted-by: Codex:gpt-5.5 > > This can and probably should just be: > > Assisted-by: LLM > > Instead of mentioning the LLM specifically used. > >> --- >> drivers/gpu/drm/nouveau/nouveau_bo.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c >> b/drivers/gpu/drm/nouveau/nouveau_bo.c >> index 0e8de6d4b36f..bdd0390b590e 100644 >> --- a/drivers/gpu/drm/nouveau/nouveau_bo.c >> +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c >> @@ -578,6 +578,7 @@ int nouveau_bo_pin_locked(struct nouveau_bo >> *nvbo, uint32_t domain, bool contig) >> "0x%08x vs 0x%08x\n", bo, >> bo->resource->mem_type, domain); >> ret = -EBUSY; >> + goto out; > > Would probably be better to just turn this into an else: > > if (error) { > NV_ERROR(drm, "bo %p pinned elsewhere: " > "0x%08x vs 0x%08x\n", bo, > bo->resource->mem_type, domain); > ret = -EBUSY; > } else { > ttm_bo_pin(&nvbo->bo); > } > > >> } >> ttm_bo_pin(&nvbo->bo); >> goto out; >> >> base-commit: df2908090cda368b01ff43709f51890076c56157 > >
Thanks for your review! V2 sent. Best, Peiyang He
