Messages in this thread | | | Date | Fri, 30 Dec 2016 10:01:39 -0500 | From | Dave Jones <> | Subject | Re: sg_io HARDENED_USERCOPY_PAGESPAN trace |
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On Fri, Dec 30, 2016 at 05:37:12AM -0800, Christoph Hellwig wrote: > On Thu, Dec 29, 2016 at 10:43:51AM -0500, Dave Jones wrote: > > On Wed, Dec 28, 2016 at 11:56:42PM -0800, Christoph Hellwig wrote: > > > On Wed, Dec 28, 2016 at 04:40:16PM -0500, Dave Jones wrote: > > > > sg_io+0x113/0x470 > > > > > > Can you resolve that to a source line using a gdb? > > > > It's the copy_from_user in an inlined copy of blk_fill_sghdr_rq. > > That must be this line right at the beginning of blk_fill_sghdr_rq > > if (copy_from_user(rq->cmd, hdr->cmdp, hdr->cmd_len)) > return -EFAULT; > > We're copying the SCSI CDB from the userspace pointer inside the hdr > we copied earlier into the request. > > req->cmd is set to req->__cmd which is a u8 array with 16 members in > struct request by default, but if hdr->cmd_len is bigger than BLK_MAX_CDB > (16) we do a separate allocation for it in the caller: > > if (hdr->cmd_len > BLK_MAX_CDB) { > rq->cmd = kzalloc(hdr->cmd_len, GFP_KERNEL); > if (!rq->cmd) > goto out_put_request; > } > > so I'm not really sure what the problem here could be.
I threw this debug printk into the pagespan code to see what exactly it was complaining about..
ptr:ffff88042614cff8 end:ffff88042614d003 n:c
so it was copying 12 bytes that spanned two pages. From my reading of the config option help text, this thing is complaining that wasn't allocated with __GFP_COMP maybe ?
Dave
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