Messages in this thread | | | Date | Fri, 30 Dec 2016 07:10:49 -0800 | From | Christoph Hellwig <> | Subject | Re: sg_io HARDENED_USERCOPY_PAGESPAN trace |
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On Fri, Dec 30, 2016 at 10:01:39AM -0500, Dave Jones wrote: > 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 ?
If this is on a devie using blk-mq the block core will use high order allocations (as high as possible) to allocate the requests for each queue, so struct request could very well span multiple pages. But I don't see what __GFP_COMP would have to do with user copy annoations. As all requests for a queue are freed togeth again there is no point in setting __GFP_COMP for the request allocations.
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