On Wed, 2012-07-25 at 20:13 +0800, Wang Sen wrote: > When using the commands below to write some data to a virtio-scsi LUN of the > QEMU guest(32-bit) with 1G physical memory(qemu -m 1024), the qemu will crash. > > # sudo mkfs.ext4 /dev/sdb (/dev/sdb is the virtio-scsi LUN.) > # sudo mount /dev/sdb /mnt > # dd if=/dev/zero of=/mnt/file bs=1M count=1024 > > In current implementation, sg_set_buf is called to add buffers to sg list which > is put into the virtqueue eventually. But if there are some HighMem pages in > table->sgl you can not get virtual address by sg_virt. So, sg_virt(sg_elem) may > return NULL value. This will cause QEMU exit when virtqueue_map_sg is called > in QEMU because an invalid GPA is passed by virtqueue. > > I take Paolo's solution mentioned in last thread to avoid failure on handling > flag bits. > > I have tested the patch on my workstation. QEMU would not crash any more. > > Signed-off-by: Wang Sen <senwang@xxxxxxxxxxxxxxxxxx> [...] This is not the correct way to submit a change for stable. See Documentation/stable_kernel_rules.txt. Ben. -- Ben Hutchings If more than one person is responsible for a bug, no one is at fault.
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