On 07/05/ , Matthew Auld wrote: > On Wed, 5 Jul 2023 at 11:08, Lang Yu <Lang.Yu@xxxxxxx> wrote: > > > > bo->kref is increased once(kref_init()) in ttm_bo_release, > > but decreased twice(ttm_bo_put()) respectively in > > ttm_bo_delayed_delete and ttm_bo_cleanup_refs, > > which is unbalanced. > > > > Just clean up bo resource in one place for a delayed deleted bo. > > > > Fixes: 9bff18d13473 ("drm/ttm: use per BO cleanup workers") > > > > [ 67.399887] refcount_t: underflow; use-after-free. > > [ 67.399901] WARNING: CPU: 0 PID: 3172 at lib/refcount.c:28 refcount_warn_saturate+0xc2/0x110 > > [ 67.400124] RIP: 0010:refcount_warn_saturate+0xc2/0x110 > > [ 67.400173] Call Trace: > > [ 67.400176] <TASK> > > [ 67.400181] ttm_mem_evict_first+0x4fe/0x5b0 [ttm] > > [ 67.400216] ttm_bo_mem_space+0x1e3/0x240 [ttm] > > [ 67.400239] ttm_bo_validate+0xc7/0x190 [ttm] > > [ 67.400253] ? ww_mutex_trylock+0x1b1/0x390 > > [ 67.400266] ttm_bo_init_reserved+0x183/0x1c0 [ttm] > > [ 67.400280] ? __rwlock_init+0x3d/0x70 > > [ 67.400292] amdgpu_bo_create+0x1cd/0x4f0 [amdgpu] > > [ 67.400607] ? __pfx_amdgpu_bo_user_destroy+0x10/0x10 [amdgpu] > > [ 67.400980] amdgpu_bo_create_user+0x38/0x70 [amdgpu] > > [ 67.401291] amdgpu_gem_object_create+0x77/0xb0 [amdgpu] > > [ 67.401641] ? __pfx_amdgpu_bo_user_destroy+0x10/0x10 [amdgpu] > > [ 67.401958] amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu+0x228/0xa30 [amdgpu] > > [ 67.402433] kfd_ioctl_alloc_memory_of_gpu+0x14e/0x390 [amdgpu] > > [ 67.402824] ? lock_release+0x13f/0x290 > > [ 67.402838] kfd_ioctl+0x1e0/0x640 [amdgpu] > > [ 67.403205] ? __pfx_kfd_ioctl_alloc_memory_of_gpu+0x10/0x10 [amdgpu] > > [ 67.403579] ? tomoyo_file_ioctl+0x19/0x20 > > [ 67.403590] __x64_sys_ioctl+0x95/0xd0 > > [ 67.403601] do_syscall_64+0x3b/0x90 > > [ 67.403609] entry_SYSCALL_64_after_hwframe+0x72/0xdc > > > > Signed-off-by: Lang Yu <Lang.Yu@xxxxxxx> > > --- > > drivers/gpu/drm/ttm/ttm_bo.c | 89 ++++-------------------------------- > > 1 file changed, 10 insertions(+), 79 deletions(-) > > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c > > index 326a3d13a829..1e073dfb1332 100644 > > --- a/drivers/gpu/drm/ttm/ttm_bo.c > > +++ b/drivers/gpu/drm/ttm/ttm_bo.c > > @@ -224,82 +224,6 @@ static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo) > > dma_resv_iter_end(&cursor); > > } > > > > -/** > > - * ttm_bo_cleanup_refs > > - * If bo idle, remove from lru lists, and unref. > > - * If not idle, block if possible. > > - * > > - * Must be called with lru_lock and reservation held, this function > > - * will drop the lru lock and optionally the reservation lock before returning. > > - * > > - * @bo: The buffer object to clean-up > > - * @interruptible: Any sleeps should occur interruptibly. > > - * @no_wait_gpu: Never wait for gpu. Return -EBUSY instead. > > - * @unlock_resv: Unlock the reservation lock as well. > > - */ > > - > > -static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo, > > - bool interruptible, bool no_wait_gpu, > > - bool unlock_resv) > > -{ > > - struct dma_resv *resv = &bo->base._resv; > > - int ret; > > - > > - if (dma_resv_test_signaled(resv, DMA_RESV_USAGE_BOOKKEEP)) > > - ret = 0; > > - else > > - ret = -EBUSY; > > - > > - if (ret && !no_wait_gpu) { > > - long lret; > > - > > - if (unlock_resv) > > - dma_resv_unlock(bo->base.resv); > > - spin_unlock(&bo->bdev->lru_lock); > > - > > - lret = dma_resv_wait_timeout(resv, DMA_RESV_USAGE_BOOKKEEP, > > - interruptible, > > - 30 * HZ); > > - > > - if (lret < 0) > > - return lret; > > - else if (lret == 0) > > - return -EBUSY; > > - > > - spin_lock(&bo->bdev->lru_lock); > > - if (unlock_resv && !dma_resv_trylock(bo->base.resv)) { > > - /* > > - * We raced, and lost, someone else holds the reservation now, > > - * and is probably busy in ttm_bo_cleanup_memtype_use. > > - * > > - * Even if it's not the case, because we finished waiting any > > - * delayed destruction would succeed, so just return success > > - * here. > > - */ > > - spin_unlock(&bo->bdev->lru_lock); > > - return 0; > > - } > > - ret = 0; > > - } > > - > > - if (ret) { > > - if (unlock_resv) > > - dma_resv_unlock(bo->base.resv); > > - spin_unlock(&bo->bdev->lru_lock); > > - return ret; > > - } > > - > > - spin_unlock(&bo->bdev->lru_lock); > > - ttm_bo_cleanup_memtype_use(bo); > > - > > - if (unlock_resv) > > - dma_resv_unlock(bo->base.resv); > > - > > - ttm_bo_put(bo); > > The put() here is indeed broken and leads to some nasty uaf I think, > but we fixed that a while back in: c00133a9e87e ("drm/ttm: drop extra > ttm_bo_put in ttm_bo_cleanup_refs"). It looks like you are using an > old tree? Perhaps the issue you are seeing was also fixed with that? Thanks. I can see this commit in my tree but it was overrode by other patches. It fixed this issue. Regards, Lang > > - > > - return 0; > > -} > > - > > /* > > * Block for the dma_resv object to become idle, lock the buffer and clean up > > * the resource and tt object. > > @@ -622,8 +546,10 @@ int ttm_mem_evict_first(struct ttm_device *bdev, > > } > > > > if (bo->deleted) { > > - ret = ttm_bo_cleanup_refs(bo, ctx->interruptible, > > - ctx->no_wait_gpu, locked); > > + if (locked) > > + dma_resv_unlock(bo->base.resv); > > + spin_unlock(&bdev->lru_lock); > > + ret = ttm_bo_wait_ctx(bo, ctx); > > ttm_bo_put(bo); > > return ret; > > } > > @@ -1146,7 +1072,12 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx, > > } > > > > if (bo->deleted) { > > - ret = ttm_bo_cleanup_refs(bo, false, false, locked); > > + struct ttm_operation_ctx ctx = { false, false }; > > + > > + if (locked) > > + dma_resv_unlock(bo->base.resv); > > + spin_unlock(&bo->bdev->lru_lock); > > + ret = ttm_bo_wait_ctx(bo, &ctx); > > ttm_bo_put(bo); > > return ret == -EBUSY ? -ENOSPC : ret; > > } > > -- > > 2.25.1 > >