virtio-gpu + spice-guest-agent #3
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@jfouquart Thank you for the link. |
mszoek
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The capture code is typically run entirely in the fence signalling
critical path. We're about to add lockdep annotation in an upcoming patch
which reveals a lockdep splat similar to the below one.
Fix the associated potential deadlocks using __GFP_KSWAPD_RECLAIM
(which is the same as GFP_WAIT, but open-coded for clarity) rather than
GFP_KERNEL for memory allocation in the capture path. This has the
potential drawback that capture might fail in situations with memory
pressure.
[ 234.842048] WARNING: possible circular locking dependency detected
[ 234.842050] 5.15.0-rc7+ #20 Tainted: G U W
[ 234.842052] ------------------------------------------------------
[ 234.842054] gem_exec_captur/1180 is trying to acquire lock:
[ 234.842056] ffffffffa3e51c00 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc+0x4d/0x330
[ 234.842063]
but task is already holding lock:
[ 234.842064] ffffffffa3f57620 (dma_fence_map){++++}-{0:0}, at: i915_vma_snapshot_resource_pin+0x27/0x30 [i915]
[ 234.842138]
which lock already depends on the new lock.
[ 234.842140]
the existing dependency chain (in reverse order) is:
[ 234.842142]
-> #2 (dma_fence_map){++++}-{0:0}:
[ 234.842145] __dma_fence_might_wait+0x41/0xa0
[ 234.842149] dma_resv_lockdep+0x1dc/0x28f
[ 234.842151] do_one_initcall+0x58/0x2d0
[ 234.842154] kernel_init_freeable+0x273/0x2bf
[ 234.842157] kernel_init+0x16/0x120
[ 234.842160] ret_from_fork+0x1f/0x30
[ 234.842163]
-> #1 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}:
[ 234.842166] fs_reclaim_acquire+0x6d/0xd0
[ 234.842168] __kmalloc_node+0x51/0x3a0
[ 234.842171] alloc_cpumask_var_node+0x1b/0x30
[ 234.842174] native_smp_prepare_cpus+0xc7/0x292
[ 234.842177] kernel_init_freeable+0x160/0x2bf
[ 234.842179] kernel_init+0x16/0x120
[ 234.842181] ret_from_fork+0x1f/0x30
[ 234.842184]
-> #0 (fs_reclaim){+.+.}-{0:0}:
[ 234.842186] __lock_acquire+0x1161/0x1dc0
[ 234.842189] lock_acquire+0xb5/0x2b0
[ 234.842192] fs_reclaim_acquire+0xa1/0xd0
[ 234.842193] __kmalloc+0x4d/0x330
[ 234.842196] i915_vma_coredump_create+0x78/0x5b0 [i915]
[ 234.842253] intel_engine_coredump_add_vma+0x36/0xe0 [i915]
[ 234.842307] __i915_gpu_coredump+0x290/0x5e0 [i915]
[ 234.842365] i915_capture_error_state+0x57/0xa0 [i915]
[ 234.842415] intel_gt_handle_error+0x348/0x3e0 [i915]
[ 234.842462] intel_gt_debugfs_reset_store+0x3c/0x90 [i915]
[ 234.842504] simple_attr_write+0xc1/0xe0
[ 234.842507] full_proxy_write+0x53/0x80
[ 234.842509] vfs_write+0xbc/0x350
[ 234.842513] ksys_write+0x58/0xd0
[ 234.842514] do_syscall_64+0x38/0x90
[ 234.842516] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 234.842519]
other info that might help us debug this:
[ 234.842521] Chain exists of:
fs_reclaim --> mmu_notifier_invalidate_range_start --> dma_fence_map
[ 234.842526] Possible unsafe locking scenario:
[ 234.842528] CPU0 CPU1
[ 234.842529] ---- ----
[ 234.842531] lock(dma_fence_map);
[ 234.842532] lock(mmu_notifier_invalidate_range_start);
[ 234.842535] lock(dma_fence_map);
[ 234.842537] lock(fs_reclaim);
[ 234.842539]
*** DEADLOCK ***
[ 234.842540] 4 locks held by gem_exec_captur/1180:
[ 234.842543] #0: ffff9007812d9460 (sb_writers#17){.+.+}-{0:0}, at: ksys_write+0x58/0xd0
[ 234.842547] #1: ffff900781d9ecb8 (&attr->mutex){+.+.}-{3:3}, at: simple_attr_write+0x3a/0xe0
[ 234.842552] #2: ffffffffc11913a8 (capture_mutex){+.+.}-{3:3}, at: i915_capture_error_state+0x1a/0xa0 [i915]
[ 234.842602] #3: ffffffffa3f57620 (dma_fence_map){++++}-{0:0}, at: i915_vma_snapshot_resource_pin+0x27/0x30 [i915]
[ 234.842656]
stack backtrace:
[ 234.842658] CPU: 0 PID: 1180 Comm: gem_exec_captur Tainted: G U W 5.15.0-rc7+ #20
[ 234.842661] Hardware name: ASUS System Product Name/PRIME B560M-A AC, BIOS 0403 01/26/2021
[ 234.842664] Call Trace:
[ 234.842666] dump_stack_lvl+0x57/0x72
[ 234.842669] check_noncircular+0xde/0x100
[ 234.842672] ? __lock_acquire+0x3bf/0x1dc0
[ 234.842675] __lock_acquire+0x1161/0x1dc0
[ 234.842678] lock_acquire+0xb5/0x2b0
[ 234.842680] ? __kmalloc+0x4d/0x330
[ 234.842683] ? finish_task_switch.isra.0+0xf2/0x360
[ 234.842686] ? i915_vma_coredump_create+0x78/0x5b0 [i915]
[ 234.842734] fs_reclaim_acquire+0xa1/0xd0
[ 234.842737] ? __kmalloc+0x4d/0x330
[ 234.842739] __kmalloc+0x4d/0x330
[ 234.842742] i915_vma_coredump_create+0x78/0x5b0 [i915]
[ 234.842793] ? capture_vma+0xbe/0x110 [i915]
[ 234.842844] intel_engine_coredump_add_vma+0x36/0xe0 [i915]
[ 234.842892] __i915_gpu_coredump+0x290/0x5e0 [i915]
[ 234.842939] i915_capture_error_state+0x57/0xa0 [i915]
[ 234.842985] intel_gt_handle_error+0x348/0x3e0 [i915]
[ 234.843032] ? __mutex_lock+0x81/0x830
[ 234.843035] ? simple_attr_write+0x3a/0xe0
[ 234.843038] ? __lock_acquire+0x3bf/0x1dc0
[ 234.843041] intel_gt_debugfs_reset_store+0x3c/0x90 [i915]
[ 234.843083] ? _copy_from_user+0x45/0x80
[ 234.843086] simple_attr_write+0xc1/0xe0
[ 234.843089] full_proxy_write+0x53/0x80
[ 234.843091] vfs_write+0xbc/0x350
[ 234.843094] ksys_write+0x58/0xd0
[ 234.843096] do_syscall_64+0x38/0x90
[ 234.843098] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 234.843101] RIP: 0033:0x7fa467480877
[ 234.843103] Code: 75 05 48 83 c4 58 c3 e8 37 4e ff ff 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
[ 234.843108] RSP: 002b:00007ffd14d79b08 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 234.843112] RAX: ffffffffffffffda RBX: 00007ffd14d79b60 RCX: 00007fa467480877
[ 234.843114] RDX: 0000000000000014 RSI: 00007ffd14d79b60 RDI: 0000000000000007
[ 234.843116] RBP: 0000000000000007 R08: 0000000000000000 R09: 00007ffd14d79ab0
[ 234.843119] R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000014
[ 234.843121] R13: 0000000000000000 R14: 00007ffd14d79b60 R15: 0000000000000005
v5:
- Use __GFP_KSWAPD_RECLAIM rather than __GFP_NOWAIT for clarity.
(Daniel Vetter)
v6:
- Include an instance in execlists_capture_work().
- Rework the commit message due to patch reordering.
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211108174547.979714-3-thomas.hellstrom@linux.intel.com
mszoek
pushed a commit
that referenced
this issue
Dec 2, 2023
We have a debugfs hook to directly call into i915_gem_shrink() with the fs_reclaim acquire annotations to simulate hitting direct reclaim. However we should also annotate this with memalloc_noreclaim, which will set PF_MEMALLOC for us on the current context, to ensure we can't re-enter direct reclaim(just like "real" direct reclaim does). This is an issue now that ttm_bo_validate could potentially be called here, which might try to allocate a tiny amount of memory to hold the new ttm_resource struct, as per the below splat: [ 2507.913844] WARNING: possible recursive locking detected [ 2507.913848] 5.16.0-rc4+ #5 Tainted: G U [ 2507.913853] -------------------------------------------- [ 2507.913856] gem_exec_captur/1825 is trying to acquire lock: [ 2507.913861] ffffffffb9df2500 (fs_reclaim){..}-{0:0}, at: kmem_cache_alloc_trace+0x30/0x390 [ 2507.913875] but task is already holding lock: [ 2507.913879] ffffffffb9df2500 (fs_reclaim){..}-{0:0}, at: i915_drop_caches_set+0x1c9/0x2c0 [i915] [ 2507.913962] other info that might help us debug this: [ 2507.913966] Possible unsafe locking scenario: [ 2507.913970] CPU0 [ 2507.913973] ---- [ 2507.913975] lock(fs_reclaim); [ 2507.913979] lock(fs_reclaim); [ 2507.913983] DEADLOCK *** [ 2507.913988] May be due to missing lock nesting notation [ 2507.913992] 4 locks held by gem_exec_captur/1825: [ 2507.913997] #0: ffff888101f6e460 (sb_writers#17){..}-{0:0}, at: ksys_write+0xe9/0x1b0 [ 2507.914009] #1: ffff88812d99e2b8 (&attr->mutex){..}-{3:3}, at: simple_attr_write+0xbb/0x220 [ 2507.914019] #2: ffffffffb9df2500 (fs_reclaim){..}-{0:0}, at: i915_drop_caches_set+0x1c9/0x2c0 [i915] [ 2507.914085] #3: ffff8881b4a11b20 (reservation_ww_class_mutex){..}-{3:3}, at: ww_mutex_trylock+0x43f/0xcb0 [ 2507.914097] stack backtrace: [ 2507.914102] CPU: 0 PID: 1825 Comm: gem_exec_captur Tainted: G U 5.16.0-rc4+ #5 [ 2507.914109] Hardware name: ASUS System Product Name/PRIME B560M-A AC, BIOS 0403 01/26/2021 [ 2507.914115] Call Trace: [ 2507.914118] <TASK> [ 2507.914121] dump_stack_lvl+0x59/0x73 [ 2507.914128] __lock_acquire.cold+0x227/0x3b0 [ 2507.914135] ? lockdep_hardirqs_on_prepare+0x410/0x410 [ 2507.914141] ? __lock_acquire+0x23ca/0x5000 [ 2507.914147] lock_acquire+0x19c/0x4b0 [ 2507.914152] ? kmem_cache_alloc_trace+0x30/0x390 [ 2507.914157] ? lock_release+0x690/0x690 [ 2507.914163] ? lock_is_held_type+0xe4/0x140 [ 2507.914170] ? ttm_sys_man_alloc+0x47/0xb0 [ttm] [ 2507.914178] fs_reclaim_acquire+0x11a/0x160 [ 2507.914183] ? kmem_cache_alloc_trace+0x30/0x390 [ 2507.914188] kmem_cache_alloc_trace+0x30/0x390 [ 2507.914192] ? lock_release+0x37f/0x690 [ 2507.914198] ttm_sys_man_alloc+0x47/0xb0 [ttm] [ 2507.914206] ttm_bo_pipeline_gutting+0x70/0x440 [ttm] [ 2507.914214] ? ttm_mem_io_free+0x150/0x150 [ttm] [ 2507.914221] ? lock_is_held_type+0xe4/0x140 [ 2507.914227] ttm_bo_validate+0x2fb/0x370 [ttm] [ 2507.914234] ? lock_acquire+0x19c/0x4b0 [ 2507.914239] ? ttm_bo_bounce_temp_buffer.constprop.0+0xf0/0xf0 [ttm] [ 2507.914246] ? lock_acquire+0x131/0x4b0 [ 2507.914251] ? lock_is_held_type+0xe4/0x140 [ 2507.914257] i915_ttm_shrinker_release_pages+0x2bc/0x490 [i915] [ 2507.914339] ? i915_ttm_swap_notify+0x130/0x130 [i915] [ 2507.914429] ? i915_gem_object_release_mmap_offset+0x32/0x250 [i915] [ 2507.914529] i915_gem_shrink+0xb14/0x1290 [i915] [ 2507.914616] ? ___i915_gem_object_make_shrinkable+0x3e0/0x3e0 [i915] [ 2507.914698] ? _raw_spin_unlock_irqrestore+0x2d/0x60 [ 2507.914705] ? track_intel_runtime_pm_wakeref+0x180/0x230 [i915] [ 2507.914777] i915_gem_shrink_all+0x4b/0x70 [i915] [ 2507.914857] i915_drop_caches_set+0x227/0x2c0 [i915] Reported-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Signed-off-by: Matthew Auld <matthew.auld@intel.com> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20211213125530.3960007-1-matthew.auld@intel.com
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Hi,
I'm using this channel to give you an information, I hope you won't mind too much. Indeed I've been following your work for a while now and I've noticed in particular that you're trying to make wayland work on VM. So I would like to give you a link that I hope will help you to progress freebsd/drm-kmod#119. I also have a port to submit to you if you want https://github.com/jfouquart/spice-guest-agent to simplify the integration with spices clients.
Thanks for your great work and good luck to you.
jfouquart.
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