On Mon, 2024-07-01 at 12:43 +0200, Christian König wrote:
> Am 28.06.24 um 20:13 schrieb Daniel Vetter:
> > On Fri, Jun 28, 2024 at 03:51:33PM +0000, Matthew Brost wrote:
> > > On Fri, Jun 28, 2024 at 05:38:48PM +0200, Thomas Hellström wrote:
> > > > Bos can be put with multiple unrelated dma-resv locks held. But
> > > > imported bos attempt to grab the bo dma-resv during dma-buf
> > > > detach
> > > > that typically happens during cleanup. That leads to lockde
> > > > splats
> > > > similar to the below and a potential ABBA deadlock.
> > > >
> > > > Fix this by always taking the delayed workqueue cleanup path
> > > > for
> > > > imported bos.
> > > >
> > > > Requesting stable fixes from when the Xe driver was introduced,
> > > > since its usage of drm_exec and wide vm dma_resvs appear to be
> > > > the first reliable trigger of this.
> > > >
> > > > [22982.116427] ============================================
> > > > [22982.116428] WARNING: possible recursive locking detected
> > > > [22982.116429] 6.10.0-rc2+ #10 Tainted: G U W
> > > > [22982.116430] --------------------------------------------
> > > > [22982.116430] glxgears:sh0/5785 is trying to acquire lock:
> > > > [22982.116431] ffff8c2bafa539a8
> > > > (reservation_ww_class_mutex){+.+.}-{3:3}, at:
> > > > dma_buf_detach+0x3b/0xf0
> > > > [22982.116438]
> > > > but task is already holding lock:
> > > > [22982.116438] ffff8c2d9aba6da8
> > > > (reservation_ww_class_mutex){+.+.}-{3:3}, at:
> > > > drm_exec_lock_obj+0x49/0x2b0 [drm_exec]
> > > > [22982.116442]
> > > > other info that might help us debug this:
> > > > [22982.116442] Possible unsafe locking scenario:
> > > >
> > > > [22982.116443] CPU0
> > > > [22982.116444] ----
> > > > [22982.116444] lock(reservation_ww_class_mutex);
> > > > [22982.116445] lock(reservation_ww_class_mutex);
> > > > [22982.116447]
> > > > *** DEADLOCK ***
> > > >
> > > > [22982.116447] May be due to missing lock nesting notation
> > > >
> > > > [22982.116448] 5 locks held by glxgears:sh0/5785:
> > > > [22982.116449] #0: ffff8c2d9aba58c8 (&xef->vm.lock){+.+.}-
> > > > {3:3}, at: xe_file_close+0xde/0x1c0 [xe]
> > > > [22982.116507] #1: ffff8c2e28cc8480 (&vm->lock){++++}-{3:3},
> > > > at: xe_vm_close_and_put+0x161/0x9b0 [xe]
> > > > [22982.116578] #2: ffff8c2e31982970 (&val->lock){.+.+}-{3:3},
> > > > at: xe_validation_ctx_init+0x6d/0x70 [xe]
> > > > [22982.116647] #3: ffffacdc469478a8
> > > > (reservation_ww_class_acquire){+.+.}-{0:0}, at:
> > > > xe_vma_destroy_unlocked+0x7f/0xe0 [xe]
> > > > [22982.116716] #4: ffff8c2d9aba6da8
> > > > (reservation_ww_class_mutex){+.+.}-{3:3}, at:
> > > > drm_exec_lock_obj+0x49/0x2b0 [drm_exec]
> > > > [22982.116719]
> > > > stack backtrace:
> > > > [22982.116720] CPU: 8 PID: 5785 Comm: glxgears:sh0 Tainted:
> > > > G U W 6.10.0-rc2+ #10
> > > > [22982.116721] Hardware name: ASUS System Product Name/PRIME
> > > > B560M-A AC, BIOS 2001 02/01/2023
> > > > [22982.116723] Call Trace:
> > > > [22982.116724] <TASK>
> > > > [22982.116725] dump_stack_lvl+0x77/0xb0
> > > > [22982.116727] __lock_acquire+0x1232/0x2160
> > > > [22982.116730] lock_acquire+0xcb/0x2d0
> > > > [22982.116732] ? dma_buf_detach+0x3b/0xf0
> > > > [22982.116734] ? __lock_acquire+0x417/0x2160
> > > > [22982.116736] __ww_mutex_lock.constprop.0+0xd0/0x13b0
> > > > [22982.116738] ? dma_buf_detach+0x3b/0xf0
> > > > [22982.116741] ? dma_buf_detach+0x3b/0xf0
> > > > [22982.116743] ? ww_mutex_lock+0x2b/0x90
> > > > [22982.116745] ww_mutex_lock+0x2b/0x90
> > > > [22982.116747] dma_buf_detach+0x3b/0xf0
> > > > [22982.116749] drm_prime_gem_destroy+0x2f/0x40 [drm]
> > > > [22982.116775] xe_ttm_bo_destroy+0x32/0x220 [xe]
> > > > [22982.116818] ? __mutex_unlock_slowpath+0x3a/0x290
> > > > [22982.116821] drm_exec_unlock_all+0xa1/0xd0 [drm_exec]
> > > > [22982.116823] drm_exec_fini+0x12/0xb0 [drm_exec]
> > > > [22982.116824] xe_validation_ctx_fini+0x15/0x40 [xe]
> > > > [22982.116892] xe_vma_destroy_unlocked+0xb1/0xe0 [xe]
> > > > [22982.116959] xe_vm_close_and_put+0x41a/0x9b0 [xe]
> > > > [22982.117025] ? xa_find+0xe3/0x1e0
> > > > [22982.117028] xe_file_close+0x10a/0x1c0 [xe]
> > > > [22982.117074] drm_file_free+0x22a/0x280 [drm]
> > > > [22982.117099] drm_release_noglobal+0x22/0x70 [drm]
> > > > [22982.117119] __fput+0xf1/0x2d0
> > > > [22982.117122] task_work_run+0x59/0x90
> > > > [22982.117125] do_exit+0x330/0xb40
> > > > [22982.117127] do_group_exit+0x36/0xa0
> > > > [22982.117129] get_signal+0xbd2/0xbe0
> > > > [22982.117131] arch_do_signal_or_restart+0x3e/0x240
> > > > [22982.117134] syscall_exit_to_user_mode+0x1e7/0x290
> > > > [22982.117137] do_syscall_64+0xa1/0x180
> > > > [22982.117139] ? lock_acquire+0xcb/0x2d0
> > > > [22982.117140] ? __set_task_comm+0x28/0x1e0
> > > > [22982.117141] ? find_held_lock+0x2b/0x80
> > > > [22982.117144] ? __set_task_comm+0xe1/0x1e0
> > > > [22982.117145] ? lock_release+0xca/0x290
> > > > [22982.117147] ? __do_sys_prctl+0x245/0xab0
> > > > [22982.117149] ? lockdep_hardirqs_on_prepare+0xde/0x190
> > > > [22982.117150] ? syscall_exit_to_user_mode+0xb0/0x290
> > > > [22982.117152] ? do_syscall_64+0xa1/0x180
> > > > [22982.117154] ? __lock_acquire+0x417/0x2160
> > > > [22982.117155] ? reacquire_held_locks+0xd1/0x1f0
> > > > [22982.117156] ? do_user_addr_fault+0x30c/0x790
> > > > [22982.117158] ? lock_acquire+0xcb/0x2d0
> > > > [22982.117160] ? find_held_lock+0x2b/0x80
> > > > [22982.117162] ? do_user_addr_fault+0x357/0x790
> > > > [22982.117163] ? lock_release+0xca/0x290
> > > > [22982.117164] ? do_user_addr_fault+0x361/0x790
> > > > [22982.117166] ? trace_hardirqs_off+0x4b/0xc0
> > > > [22982.117168] ? clear_bhb_loop+0x45/0xa0
> > > > [22982.117170] ? clear_bhb_loop+0x45/0xa0
> > > > [22982.117172] ? clear_bhb_loop+0x45/0xa0
> > > > [22982.117174] entry_SYSCALL_64_after_hwframe+0x76/0x7e
> > > > [22982.117176] RIP: 0033:0x7f943d267169
> > > > [22982.117192] Code: Unable to access opcode bytes at
> > > > 0x7f943d26713f.
> > > > [22982.117193] RSP: 002b:00007f9430bffc80 EFLAGS: 00000246
> > > > ORIG_RAX: 00000000000000ca
> > > > [22982.117195] RAX: fffffffffffffe00 RBX: 0000000000000000 RCX:
> > > > 00007f943d267169
> > > > [22982.117196] RDX: 0000000000000000 RSI: 0000000000000189 RDI:
> > > > 00005622f89579d0
> > > > [22982.117197] RBP: 00007f9430bffcb0 R08: 0000000000000000 R09:
> > > > 00000000ffffffff
> > > > [22982.117198] R10: 0000000000000000 R11: 0000000000000246 R12:
> > > > 0000000000000000
> > > > [22982.117199] R13: 0000000000000000 R14: 0000000000000000 R15:
> > > > 00005622f89579d0
> > > > [22982.117202] </TASK>
> > > >
> > > > Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for
> > > > Intel GPUs")
> > > > Cc: Christian König <christian.koenig@xxxxxxx>
> > > > Cc: Daniel Vetter <daniel@xxxxxxxx>
> > > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > Cc: intel-xe@xxxxxxxxxxxxxxxxxxxxx
> > > > Cc: <stable@xxxxxxxxxxxxxxx> # v6.8+
> > > Patch and explaination makes sense to me.
> > >
> > > Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> > I guess for stable this is good since minimal, but after Thomas
> > explaine
> > what he meant with dma_buf_detach_unlocked I think that total sense
> > as a
> > follow-up patch maybe.
> >
> > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
>
> IIRC the last time this issue came up a possible solution discussed
> was
> to change dma_buf_detach() so that it should always be called with
> the
> reservation lock held.
>
> The problem at the time was that this meant changing
> dmabuf->ops->detach() to also be called with that lock held and after
> that nobody looked into it any more.
>
> Anyway Reviewed-by: Christian König <christian.koenig@xxxxxxx> for
> this
> patch.
Thanks for review. It looks like a dma-buf fix would involve a number
of drivers so pushed this to drm-misc-fixes for now. It looks like both
radeon and amdgpu may potentially suffer from this. Nouveau does detach
in gem_release which looks incorrect if gpu access is going on at that
point.
So will probably need to be properly revisited.
/Thomas
>
> Regards,
> Christian.
>
> >
> > Cheers, Sima
> > > > Signed-off-by: Thomas Hellström
> > > > <thomas.hellstrom@xxxxxxxxxxxxxxx>
> > > > ---
> > > > drivers/gpu/drm/ttm/ttm_bo.c | 1 +
> > > > 1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
> > > > b/drivers/gpu/drm/ttm/ttm_bo.c
> > > > index 6396dece0db1..2427be8bc97f 100644
> > > > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > > > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > > > @@ -346,6 +346,7 @@ static void ttm_bo_release(struct kref
> > > > *kref)
> > > > if (!dma_resv_test_signaled(bo->base.resv,
> > > >
> > > > DMA_RESV_USAGE_BOOKKEEP) ||
> > > > (want_init_on_free() && (bo->ttm != NULL))
> > > > ||
> > > > + bo->type == ttm_bo_type_sg ||
> > > > !dma_resv_trylock(bo->base.resv)) {
> > > > /* The BO is not idle, resurrect it
> > > > for delayed destroy */
> > > > ttm_bo_flush_all_fences(bo);
> > > > --
> > > > 2.44.0
> > > >
>
