Hi Christian,
On 2021/4/3 0:25, Christian König wrote:
Hi Qu,
Am 02.04.21 um 05:18 schrieb Qu Huang:
Before dma_resv_lock(bo->base.resv, NULL) in amdgpu_bo_release_notify(), the bo->base.resv lock may be held by ttm_mem_evict_first(),
That can't happen since when bo_release_notify is called the BO has not more references and is therefore deleted.
And we never evict a deleted BO, we just wait for it to become idle.
Yes, the bo reference counter return to zero will enter ttm_bo_release(),but notify bo release (call amdgpu_bo_release_notify()) first happen, and then test if a reservation object's fences have been signaled, and then mark bo as deleted and remove bo from the LRU list.
When ttm_bo_release() and ttm_mem_evict_first() is concurrent, the Bo has not been removed from the LRU list and is not marked as deleted, this will happen.
As a test, when we use CPU memset instead of SDMA fill in amdgpu_bo_release_notify(), the result is page fault:
PID: 5490 TASK: ffff8e8136e04100 CPU: 4 COMMAND: "gemmPerf" #0 [ffff8e79eaa17970] machine_kexec at ffffffffb2863784 #1 [ffff8e79eaa179d0] __crash_kexec at ffffffffb291ce92 #2 [ffff8e79eaa17aa0] crash_kexec at ffffffffb291cf80 #3 [ffff8e79eaa17ab8] oops_end at ffffffffb2f6c768 #4 [ffff8e79eaa17ae0] no_context at ffffffffb2f5aaa6 #5 [ffff8e79eaa17b30] __bad_area_nosemaphore at ffffffffb2f5ab3d #6 [ffff8e79eaa17b80] bad_area_nosemaphore at ffffffffb2f5acae #7 [ffff8e79eaa17b90] __do_page_fault at ffffffffb2f6f6c0 #8 [ffff8e79eaa17c00] do_page_fault at ffffffffb2f6f925 #9 [ffff8e79eaa17c30] page_fault at ffffffffb2f6b758 [exception RIP: memset+31] RIP: ffffffffb2b8668f RSP: ffff8e79eaa17ce8 RFLAGS: 00010a17 RAX: bebebebebebebebe RBX: ffff8e747bff10c0 RCX: 0000060b00200000 RDX: 0000000000000000 RSI: 00000000000000be RDI: ffffab807f000000 RBP: ffff8e79eaa17d10 R8: ffff8e79eaa14000 R9: ffffab7c80000000 R10: 000000000000bcba R11: 00000000000001ba R12: ffff8e79ebaa4050 R13: ffffab7c80000000 R14: 0000000000022600 R15: ffff8e8136e04100 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #10 [ffff8e79eaa17ce8] amdgpu_bo_release_notify at ffffffffc092f2d1 [amdgpu] #11 [ffff8e79eaa17d18] ttm_bo_release at ffffffffc08f39dd [amdttm] #12 [ffff8e79eaa17d58] amdttm_bo_put at ffffffffc08f3c8c [amdttm] #13 [ffff8e79eaa17d68] amdttm_bo_vm_close at ffffffffc08f7ac9 [amdttm] #14 [ffff8e79eaa17d80] remove_vma at ffffffffb29ef115 #15 [ffff8e79eaa17da0] exit_mmap at ffffffffb29f2c64 #16 [ffff8e79eaa17e58] mmput at ffffffffb28940c7 #17 [ffff8e79eaa17e78] do_exit at ffffffffb289dc95 #18 [ffff8e79eaa17f10] do_group_exit at ffffffffb289e4cf #19 [ffff8e79eaa17f40] sys_exit_group at ffffffffb289e544 #20 [ffff8e79eaa17f50] system_call_fastpath at ffffffffb2f74ddb
Regards, Qu.
Regards, Christian.
and the VRAM mem will be evicted, mem region was replaced by Gtt mem region. amdgpu_bo_release_notify() will then hold the bo->base.resv lock, and SDMA will get an invalid address in amdgpu_fill_buffer(), resulting in a VMFAULT or memory corruption.
To avoid it, we have to hold bo->base.resv lock first, and check whether the mem.mem_type is TTM_PL_VRAM.
Signed-off-by: Qu Huang jinsdb@126.com
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c index 4b29b82..8018574 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c @@ -1300,12 +1300,16 @@ void amdgpu_bo_release_notify(struct ttm_buffer_object *bo) if (bo->base.resv == &bo->base._resv) amdgpu_amdkfd_remove_fence_on_pt_pd_bos(abo);
- if (bo->mem.mem_type != TTM_PL_VRAM || !bo->mem.mm_node || - !(abo->flags & AMDGPU_GEM_CREATE_VRAM_WIPE_ON_RELEASE)) + if (!(abo->flags & AMDGPU_GEM_CREATE_VRAM_WIPE_ON_RELEASE)) return;
dma_resv_lock(bo->base.resv, NULL);
+ if (bo->mem.mem_type != TTM_PL_VRAM || !bo->mem.mm_node) { + dma_resv_unlock(bo->base.resv); + return; + }
r = amdgpu_fill_buffer(abo, AMDGPU_POISON, bo->base.resv, &fence); if (!WARN_ON(r)) { amdgpu_bo_fence(abo, fence, false); -- 1.8.3.1