On Thu, Mar 01, 2018 at 09:33:35AM -0500, Farhan Ali wrote: > Hi, > > I have been noticing some segfaults for QEMU on s390x, and I have been > hitting this issue quite reliably (at least once in 10 runs of a test case). > The qemu version is 2.11.50, and I have systemd created coredumps > when this happens. > > Here is a back trace of the segfaulting thread:
The backtrace looks normal. Please post the QEMU command-line and the details of the segfault (which memory access faulted?). > #0 0x000003ffafed202c in swapcontext () from /lib64/libc.so.6 > #1 0x000002aa355c02ee in qemu_coroutine_new () at > util/coroutine-ucontext.c:164 > #2 0x000002aa355bec34 in qemu_coroutine_create > (entry=entry@entry=0x2aa3550f7a8 <blk_aio_read_entry>, > opaque=opaque@entry=0x3ffa002afa0) at util/qemu-coroutine.c:76 > #3 0x000002aa35510262 in blk_aio_prwv (blk=0x2aa65fbefa0, offset=<optimized > out>, bytes=<optimized out>, qiov=0x3ffa002a9c0, > co_entry=co_entry@entry=0x2aa3550f7a8 <blk_aio_read_entry>, flags=0, > cb=0x2aa35340a50 <virtio_blk_rw_complete>, opaque=0x3ffa002a960) at > block/block-backend.c:1299 > #4 0x000002aa35510376 in blk_aio_preadv (blk=<optimized out>, > offset=<optimized out>, qiov=<optimized out>, flags=<optimized out>, > cb=<optimized out>, opaque=0x3ffa002a960) at block/block-backend.c:1392 > #5 0x000002aa3534114e in submit_requests (niov=<optimized out>, > num_reqs=<optimized out>, start=<optimized out>, mrb=<optimized out>, > blk=<optimized out>) at > /usr/src/debug/qemu-2.11.50/hw/block/virtio-blk.c:372 > #6 virtio_blk_submit_multireq (blk=<optimized out>, > mrb=mrb@entry=0x3ffad77e640) at > /usr/src/debug/qemu-2.11.50/hw/block/virtio-blk.c:402 > #7 0x000002aa353422e0 in virtio_blk_handle_vq (s=0x2aa6611e7d8, > vq=0x3ffb0f5f010) at /usr/src/debug/qemu-2.11.50/hw/block/virtio-blk.c:620 > #8 0x000002aa3536655a in virtio_queue_notify_aio_vq > (vq=vq@entry=0x3ffb0f5f010) at > /usr/src/debug/qemu-2.11.50/hw/virtio/virtio.c:1515 > #9 0x000002aa35366cd6 in virtio_queue_notify_aio_vq (vq=0x3ffb0f5f010) at > /usr/src/debug/qemu-2.11.50/hw/virtio/virtio.c:1511 > #10 virtio_queue_host_notifier_aio_poll (opaque=0x3ffb0f5f078) at > /usr/src/debug/qemu-2.11.50/hw/virtio/virtio.c:2409 > #11 0x000002aa355a8ba4 in run_poll_handlers_once > (ctx=ctx@entry=0x2aa65f99310) at util/aio-posix.c:497 > #12 0x000002aa355a9b74 in run_poll_handlers (max_ns=<optimized out>, > ctx=0x2aa65f99310) at util/aio-posix.c:534 > #13 try_poll_mode (blocking=true, ctx=0x2aa65f99310) at util/aio-posix.c:562 > #14 aio_poll (ctx=0x2aa65f99310, blocking=blocking@entry=true) at > util/aio-posix.c:602 > #15 0x000002aa353d2d0a in iothread_run (opaque=0x2aa65f990f0) at > iothread.c:60 > #16 0x000003ffb0f07e82 in start_thread () from /lib64/libpthread.so.0 > #17 0x000003ffaff91596 in thread_start () from /lib64/libc.so.6 > > > I don't have much knowledge about i/o threads and the block layer code in > QEMU, so I would like to report to the community about this issue. > I believe this very similar to the bug that I reported upstream couple of > days ago > (https://lists.gnu.org/archive/html/qemu-devel/2018-02/msg04452.html). > > Any help would be greatly appreciated. > > Thanks > Farhan >
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