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d20b484c67
If *any* object of a certain WW mutex class is locked, lockdep will
consider *all* mutexes of that class as locked. Also the lock allocation
tracking code will apparently register only the address of the first
mutex of a given class locked in a sequence.
This has the odd consequence that if that first mutex is unlocked while
other mutexes of the same class remain locked and then its memory then
freed, the lock alloc tracking code will incorrectly assume that memory
is freed with a held lock in there.
For now, work around that for drm_exec by releasing the first grabbed
object lock last.
v2:
- Fix a typo (Danilo Krummrich)
- Reword the commit message a bit.
- Add a Fixes: tag
Related lock alloc tracking warning:
[ 322.660067] =========================
[ 322.660070] WARNING: held lock freed!
[ 322.660074] 6.5.0-rc7+ #155 Tainted: G U N
[ 322.660078] -------------------------
[ 322.660081] kunit_try_catch/4981 is freeing memory ffff888112adc000-ffff888112adc3ff, with a lock still held there!
[ 322.660089] ffff888112adc1a0 (reservation_ww_class_mutex){+.+.}-{3:3}, at: drm_exec_lock_obj+0x11a/0x600 [drm_exec]
[ 322.660104] 2 locks held by kunit_try_catch/4981:
[ 322.660108] #0: ffffc9000343fe18 (reservation_ww_class_acquire){+.+.}-{0:0}, at: test_early_put+0x22f/0x490 [drm_exec_test]
[ 322.660123] #1: ffff888112adc1a0 (reservation_ww_class_mutex){+.+.}-{3:3}, at: drm_exec_lock_obj+0x11a/0x600 [drm_exec]
[ 322.660135]
stack backtrace:
[ 322.660139] CPU: 7 PID: 4981 Comm: kunit_try_catch Tainted: G U N 6.5.0-rc7+ #155
[ 322.660146] Hardware name: ASUS System Product Name/PRIME B560M-A AC, BIOS 0403 01/26/2021
[ 322.660152] Call Trace:
[ 322.660155] <TASK>
[ 322.660158] dump_stack_lvl+0x57/0x90
[ 322.660164] debug_check_no_locks_freed+0x20b/0x2b0
[ 322.660172] slab_free_freelist_hook+0xa1/0x160
[ 322.660179] ? drm_exec_unlock_all+0x168/0x2a0 [drm_exec]
[ 322.660186] __kmem_cache_free+0xb2/0x290
[ 322.660192] drm_exec_unlock_all+0x168/0x2a0 [drm_exec]
[ 322.660200] drm_exec_fini+0xf/0x1c0 [drm_exec]
[ 322.660206] test_early_put+0x289/0x490 [drm_exec_test]
[ 322.660215] ? __pfx_test_early_put+0x10/0x10 [drm_exec_test]
[ 322.660222] ? __kasan_check_byte+0xf/0x40
[ 322.660227] ? __ksize+0x63/0x140
[ 322.660233] ? drmm_add_final_kfree+0x3e/0xa0 [drm]
[ 322.660289] ? _raw_spin_unlock_irqrestore+0x30/0x60
[ 322.660294] ? lockdep_hardirqs_on+0x7d/0x100
[ 322.660301] ? __pfx_kunit_try_run_case+0x10/0x10 [kunit]
[ 322.660310] ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10 [kunit]
[ 322.660319] kunit_generic_run_threadfn_adapter+0x4a/0x90 [kunit]
[ 322.660328] kthread+0x2e7/0x3c0
[ 322.660334] ? __pfx_kthread+0x10/0x10
[ 322.660339] ret_from_fork+0x2d/0x70
[ 322.660345] ? __pfx_kthread+0x10/0x10
[ 322.660349] ret_from_fork_asm+0x1b/0x30
[ 322.660358] </TASK>
[ 322.660818] ok 8 test_early_put
Cc: Christian König <christian.koenig@amd.com>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.