Hi Naresh,

On Tue, May 16, 2023 at 11:58:40AM +0530, Naresh Kamboju wrote:

Following kernel BUG noticed while running selftests arm64 fp-stress running stable rc kernel versions 6.1.29-rc1 and 6.3.3-rc1.

Is there a known-good build so that we could attempt a bisection?

Reported-by: Linux Kernel Functional Testing lkft@linaro.org

# selftests: arm64: fp-stress # TAP version 13 # 1..80 # # 8 CPUs, 3 SVE VLs, 3 SME VLs, SME2 absent # # Will run for 10s ...

# # ZA-VL-32-4: PID: 1091

# # [ 263.834190]

[ 263.834270] BUG: KFENCE: memory corruption in fpsimd_release_task+0x28/0x50 [ 263.834270] ZA-V[ 263.834419] Corrupted memory at 0x00000000d9c0a375 [ ! ! ! ! ! ! . . . . . . . . . . ] (in kfence-#158): L-64-[ 263.834929] fpsimd_release_task+0x28/0x50 [ 263.835074] arch_release_task_struct+0x1c/0x30 [ 263.835221] __put_task_struct+0x164/0x220 [ 263.835336] delayed_put_task_struct+0x60/0x128 4: [ 263.835484] rcu_core+0x318/0x950 [ 263.835632] rcu_core_si+0x1c/0x30 [ 263.835770] __do_softirq+0x110/0x3d8 Stre[ 263.835874] run_ksoftirqd+0x40/0xe0 [ 263.835994] smpboot_thread_fn+0x1d0/0x260 [ 263.836105] kthread+0xec/0x190 [ 263.836221] ret_from_fork+0x10/0x20 [ 263.836342] ami[ 263.836393] kfence-#158: 0x00000000c8819329-0x000000009e00cc22, size=546, cache=kmalloc-1k [ 263.836393] [ 263.836527] allocated by task 1112 on cpu 5 at 252.422888s: [ 263.836697] do_sme_acc+0xa8/0x230 ng m[ 263.836821] el0_sme_acc+0x40/0xa0 [ 263.836966] el0t_64_sync_handler+0xa8/0xf0 [ 263.837114] el0t_64_sync+0x190/0x198

Mark -- given that this is an SME allocation, please can you take a look? I think the implication of the kfence report is that we're writing beyond the end of 'task->thread.sme_state' at some point and corrupting the redzone.

There are two reports here, so hopefully it's not too hard to repro.

Will