Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
OnePlus 5/5T, Xiaomi Mi 6, F(x)tec Pro¹ (2019 QX1000 model) & Sony Xperia XZ Premium (UNTESTED!)
c1d1746f6d
The idea of taking the reset lock around writing the fence register was to serialise the mmio write we also perform during the reset where those registers get clobbered. However, the lock is overkill as write tearing between reset and fence_update() is harmless; the final value of the fence register is the same. A race between revoke_fences() and fence_update() is also harmless at this point as on the fault path where this is necessary, we acquire the reset lock to coordinate ourselves in the upper layer. The danger of acquiring the reset lock again in fence_update() is that we may recurse from the shrinker along the i915_gem_fault() path. <4> [125.739646] ============================================ <4> [125.739652] WARNING: possible recursive locking detected <4> [125.739659] 5.0.0-rc6-ga6e4cbf00557-drmtip_223+ #1 Tainted: G U <4> [125.739666] -------------------------------------------- <4> [125.739672] gem_mmap_gtt/1017 is trying to acquire lock: <4> [125.739679] 00000000a730190a (&dev_priv->gpu_error.reset_backoff_srcu){+.+.}, at: i915_reset_trylock+0x0/0x310 [i915] <4> [125.739848] but task is already holding lock: <4> [125.739854] 00000000a730190a (&dev_priv->gpu_error.reset_backoff_srcu){+.+.}, at: i915_reset_trylock+0x192/0x310 [i915] <4> [125.739918] other info that might help us debug this: <4> [125.739925] Possible unsafe locking scenario: <4> [125.739930] CPU0 <4> [125.739934] ---- <4> [125.739937] lock(&dev_priv->gpu_error.reset_backoff_srcu); <4> [125.739944] lock(&dev_priv->gpu_error.reset_backoff_srcu); <4> [125.739950] *** DEADLOCK *** <4> [125.739958] May be due to missing lock nesting notation <4> [125.739966] 5 locks held by gem_mmap_gtt/1017: <4> [125.739972] #0: 00000000471f682c (&mm->mmap_sem){++++}, at: __do_page_fault+0x133/0x500 <4> [125.739987] #1: 0000000026542685 (&dev->struct_mutex){+.+.}, at: i915_gem_fault+0x1f6/0x860 [i915] <4> [125.740061] #2: 00000000a730190a (&dev_priv->gpu_error.reset_backoff_srcu){+.+.}, at: i915_reset_trylock+0x192/0x310 [i915] <4> [125.740126] #3: 00000000c828eb4f (fs_reclaim){+.+.}, at: fs_reclaim_acquire.part.25+0x0/0x30 <4> [125.740140] #4: 000000002d360d65 (shrinker_rwsem){++++}, at: shrink_slab+0x1cb/0x2c0 <4> [125.740151] stack backtrace: <4> [125.740159] CPU: 1 PID: 1017 Comm: gem_mmap_gtt Tainted: G U 5.0.0-rc6-ga6e4cbf00557-drmtip_223+ #1 <4> [125.740170] Hardware name: Dell Inc. OptiPlex 745 /0GW726, BIOS 2.3.1 05/21/2007 <4> [125.740180] Call Trace: <4> [125.740189] dump_stack+0x67/0x9b <4> [125.740199] __lock_acquire+0xc75/0x1b00 <4> [125.740209] ? arch_tlb_finish_mmu+0x2a/0xa0 <4> [125.740216] ? tlb_finish_mmu+0x1a/0x30 <4> [125.740222] ? zap_page_range_single+0xe2/0x130 <4> [125.740230] ? lock_acquire+0xa6/0x1c0 <4> [125.740237] lock_acquire+0xa6/0x1c0 <4> [125.740296] ? i915_clear_error_registers+0x280/0x280 [i915] <4> [125.740357] i915_reset_trylock+0x44/0x310 [i915] <4> [125.740417] ? i915_clear_error_registers+0x280/0x280 [i915] <4> [125.740426] ? lockdep_hardirqs_on+0xe0/0x1b0 <4> [125.740434] ? _raw_spin_unlock_irqrestore+0x39/0x60 <4> [125.740499] fence_update+0x218/0x470 [i915] <4> [125.740571] i915_vma_unbind+0xa6/0x550 [i915] <4> [125.740640] i915_gem_object_unbind+0xfa/0x190 [i915] <4> [125.740711] i915_gem_shrink+0x2dc/0x590 [i915] <4> [125.740722] ? ___preempt_schedule+0x16/0x18 <4> [125.740792] ? i915_gem_shrinker_scan+0xc9/0x130 [i915] <4> [125.740861] i915_gem_shrinker_scan+0xc9/0x130 [i915] <4> [125.740870] do_shrink_slab+0x143/0x3f0 <4> [125.740878] shrink_slab+0x228/0x2c0 <4> [125.740886] shrink_node+0x167/0x450 <4> [125.740894] do_try_to_free_pages+0xc4/0x340 <4> [125.740902] try_to_free_pages+0xdc/0x2e0 <4> [125.740911] __alloc_pages_nodemask+0x662/0x1110 <4> [125.740921] ? reacquire_held_locks+0xb5/0x1b0 <4> [125.740928] ? reacquire_held_locks+0xb5/0x1b0 <4> [125.740986] ? i915_reset_trylock+0x192/0x310 [i915] <4> [125.741045] ? i915_memcpy_init_early+0x30/0x30 [i915] <4> [125.741054] pte_alloc_one+0x12/0x70 <4> [125.741060] __pte_alloc+0x11/0xf0 <4> [125.741067] apply_to_page_range+0x37e/0x440 <4> [125.741127] remap_io_mapping+0x6c/0x100 [i915] <4> [125.741196] i915_gem_fault+0x5a9/0x860 [i915] <4> [125.741204] ? ptlock_alloc+0x15/0x30 <4> [125.741212] __do_fault+0x2c/0xb0 <4> [125.741218] __handle_mm_fault+0x8ee/0xfa0 <4> [125.741227] handle_mm_fault+0x196/0x3a0 <4> [125.741235] __do_page_fault+0x246/0x500 <4> [125.741243] ? page_fault+0x8/0x30 <4> [125.741250] page_fault+0x1e/0x30 <4> [125.741256] RIP: 0033:0x55d0cc456e12 <4> [125.741264] Code: b0 df ff ff 89 c2 8b 85 70 df ff ff 01 c2 8b 85 70 df ff ff 48 98 48 8d 0c 85 00 00 00 00 48 8b 85 e0 df ff ff 48 01 c8 f7 d2 <89> 10 83 85 70 df ff ff 01 81 bd 70 df ff ff ff 03 00 00 7e be 48 <4> [125.741280] RSP: 002b:00007ffc1bab7ab0 EFLAGS: 00010206 <4> [125.741287] RAX: 00007fc787cb6000 RBX: 0000000000000000 RCX: 0000000000000000 <4> [125.741295] RDX: 00000000ffffffff RSI: 0000000000005401 RDI: 0000000000000002 <4> [125.741303] RBP: 00007ffc1bab9b70 R08: 00007ffc1bab7920 R09: 000000000000001b <4> [125.741310] R10: 7165722074736554 R11: 0000000000000246 R12: 000055d0cc454a80 <4> [125.741318] R13: 00007ffc1bab9f60 R14: 0000000000000000 R15: 0000000000000000 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109665 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190219122215.8941-4-chris@chris-wilson.co.uk |
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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.