lkml.org 
[lkml]   [2006]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 10 of 20] ipath - support for userspace apps using core driver
    From
    Date
    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.

    <b

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-03-16 18:43    [W:3.334 / U:0.128 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site