Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-09 Thread Michael S. Tsirkin
On Wed, Jan 04, 2017 at 08:25:05AM +0300, Christoph Hellwig wrote: > Most users of BLOCK_PC requests allocate the sense buffer on the stack, > so to avoid DMA to the stack copy them to a field in the heap allocated > virtblk_req structure. Without that any attempt at SCSI passthrough I/O, > includ

Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-09 Thread Jens Axboe
On 01/09/2017 06:35 AM, Christoph Hellwig wrote: > Is someone going to pick the patch up and send it to Linus? I keep > running into all kinds of boot failures whenever I forget to cherry > pick it into my development trees.. I'll add it. -- Jens Axboe _

Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-09 Thread Christoph Hellwig
Is someone going to pick the patch up and send it to Linus? I keep running into all kinds of boot failures whenever I forget to cherry pick it into my development trees.. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://

Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-06 Thread 王金浦
Hi Christoph, 2017-01-04 6:25 GMT+01:00 Christoph Hellwig : > Most users of BLOCK_PC requests allocate the sense buffer on the stack, > so to avoid DMA to the stack copy them to a field in the heap allocated > virtblk_req structure. Without that any attempt at SCSI passthrough I/O, > including th

Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-06 Thread 王金浦
2017-01-05 10:57 GMT+01:00 Christoph Hellwig : > On Wed, Jan 04, 2017 at 04:47:03PM +0100, 王金浦 wrote: >> This sounds scary. >> Could you share how to reproduce it, this should go into stable if >> it's the case. > > Step 1: Build your kernel with CONFIG_VMAP_STACK=y > Step 2: issue a SG_IO ioctl, e

Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-05 Thread Christoph Hellwig
On Thu, Jan 05, 2017 at 11:37:46AM +0100, 王金浦 wrote: > Thanks, so it's only relevant to kernel > 4.9, as CONFIG_VMAP_STACK > only introduced in 4.9 kernel. kernel >= 4.9, but otherwise, yes. ___ Virtualization mailing list Virtualization@lists.linux-fo

Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-05 Thread Christoph Hellwig
On Wed, Jan 04, 2017 at 04:47:03PM +0100, 王金浦 wrote: > This sounds scary. > Could you share how to reproduce it, this should go into stable if > it's the case. Step 1: Build your kernel with CONFIG_VMAP_STACK=y Step 2: issue a SG_IO ioctl, e.g. sg_inq /dev/vda

Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-03 Thread Jason Wang
On 2017年01月04日 13:25, Christoph Hellwig wrote: Most users of BLOCK_PC requests allocate the sense buffer on the stack, so to avoid DMA to the stack copy them to a field in the heap allocated virtblk_req structure. Without that any attempt at SCSI passthrough I/O, including the SG_IO ioctl from

[PATCH] virtio_blk: avoid DMA to stack for the sense buffer

2017-01-03 Thread Christoph Hellwig
Most users of BLOCK_PC requests allocate the sense buffer on the stack, so to avoid DMA to the stack copy them to a field in the heap allocated virtblk_req structure. Without that any attempt at SCSI passthrough I/O, including the SG_IO ioctl from userspace will crash the kernel. Note that this i