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Peiyang He 6a6870d307 drm/nouveau: don't bump pin count on failed re-pin in nouveau_bo_pin_locked()
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 calling ttm_bo_pin() only when the existing placement is compatible
with the new pin request. This matches the correct behavior in other DRM
drivers such as amdgpu_bo_pin() in amdgpu.

Cc: stable@vger.kernel.org
Fixes: ad76b3f7c7 ("drm/nouveau: teach nouveau_bo_pin() how to force a contig vram allocation")
Signed-off-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
Assisted-by: LLM
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patch.msgid.link/EACEF2F4E098413F+20260918025312.2814889-1-peiyang_he@smail.nju.edu.cn
History 2026-09-18 14:14:20 -04:00
arch Miscellaneous perf events fixes: 2026-09-13 08:44:54 -07:00
block block: save page offset gaps in cloned bio 2026-09-01 08:42:34 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This push fixes a memory allocation overrun in crypto acomp. 2026-08-28 09:28:40 -07:00
Documentation Changes since last update: 2026-09-12 08:18:50 -07:00
drivers drm/nouveau: don't bump pin count on failed re-pin in nouveau_bo_pin_locked() 2026-09-18 14:14:20 -04:00
fs xfs: fixes for 7.3-rc3 2026-09-12 08:44:12 -07:00
include Merge fdo/drm/drm-fixes into drm-misc-fixes 2026-09-16 09:43:25 +02:00
init Bootconfig fixes for v7.3-rc3 2026-09-13 09:16:36 -07:00
io_uring io_uring-7.3-20260911 2026-09-11 12:36:13 -07:00
ipc mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
kernel tracing fixes for 7.3: 2026-09-13 12:27:00 -07:00
lib block-7.3-20260911 2026-09-11 12:38:44 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm slab fixes for 7.3-rc2 2026-09-11 11:56:33 -07:00
net Nothing too exciting, usual stream of fixes. 2026-09-10 14:07:48 -07:00
rust Rust fixes for v7.3 (2nd) 2026-09-13 09:28:28 -07:00
samples rust: samples: add missing newlines in rust_print_main 2026-09-01 02:20:22 +02:00
scripts Fix misc objtool bugs: 2026-09-13 08:37:11 -07:00
security landlock: Test trace path output boundaries 2026-09-08 11:49:39 +02:00
sound sound fixes for 7.3-rc3 2026-09-11 10:00:07 -07:00
tools Bootconfig fixes for v7.3-rc3 2026-09-13 09:16:36 -07:00
usr usr: Correct a spelling by changing a letter 2026-08-05 14:51:58 +02:00
virt Arm: 2026-08-25 11:48:04 -07:00
.clang-format drm/bridge: rename drm_for_each_bridge_in_chain_scoped() to drm_for_each_bridge_in_chain() 2026-07-14 17:55:51 +02:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add Nathan Chancellor 2026-08-03 21:10:12 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap mailmap: update entry for Jens Axboe 2026-09-11 15:41:26 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Driver core fixes for 7.3-rc2 2026-09-05 11:59:05 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS IOMMU fixes for Linux v7.3-rc3: 2026-09-12 07:55:52 -07:00
Makefile Linux 7.3-rc3 2026-09-13 14:38:02 -07:00
README README: remove out of place emdashes 2026-07-15 10:51:29 -06:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer: Getting started with kernel development
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* System Administrator: Configuring and troubleshooting
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For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
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* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

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-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
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* Networking Stack: Documentation/networking/index.rst
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---------------

Security documentation and hardening guides:

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-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
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--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
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----------

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* Maintainer Handbook: Documentation/maintainer/index.rst
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-----------------------

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-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
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=========================

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