Messages in this thread | | | Subject | Re: [PATCH 10 of 20] ipath - support for userspace apps using core driver | From | Bryan O'Sullivan <> | Date | Thu, 16 Mar 2006 09:40:32 -0800 |
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On Thu, 2006-03-16 at 17:23 +0000, Hugh Dickins wrote:
> You're safe to drop the VM_SHM everywhere. But your backport driver will > have to be using PageReserved still, not relying on __GFP_COMP: although > __GFP_COMP was defined in 2.6.9 and a few earlier, it used to take effect > only when #ifdef CONFIG_HUGETLB_PAGE - only in 2.6.15 did we make it > available to all configurations. You'll have irritating accounting > differences between the two drivers: it used to be the case that put_page > on a PageReserved page did nothing, so you had to avoid get_page on it to > get the page accounting right; we straightened that out in 2.6.15.
OK, that's very helpful to know, thanks.
> So, if your driver allows userspace to pin an otherwise unlimited > number of user pages for an indefinite length of time, you ought > to follow uverbs_mem.c's locked_vm accounting.
This is exactly the case, and we are in fact aping uverbs_mem.c quite carefully :-)
> And I'll have confused you by mentioning that under VM_LOCKED: > I was thinking uverbs_mem.c set VM_LOCKED, but it does not, nor > should it.
OK, thanks.
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