On Thu, Jun 08, 2023 at 01:49:27PM -0700, Mike Kravetz wrote:
> This effectively reverts commit 16c243e99d33 ("udmabuf: Add support
> for mapping hugepages (v4)"). Recently, Junxiao Chang found a BUG
> with page map counting as described here [1]. This issue pointed out
> that the udmabuf driver
Skimming over at shmem_read_mapping_page() users, I assume most of
them
use a VM_PFNMAP mapping (or don't mmap them at all), where we won't be
messing with the struct page at all.
(That might even allow you to mmap hugetlb sub-pages, because the struct
page -- and mapcount -- will be ignored c
Hi David,
>
> On 13.06.23 10:26, Kasireddy, Vivek wrote:
> > Hi David,
> >
> >>
> >> On 12.06.23 09:10, Kasireddy, Vivek wrote:
> >>> Hi Mike,
> >>
> >> Hi Vivek,
> >>
> >>>
> >>> Sorry for the late reply; I just got back from vacation.
> >>> If it is unsafe to directly use the subpages of a huge
On Tue, 13 Jun 2023, David Hildenbrand wrote:
> On 13.06.23 10:26, Kasireddy, Vivek wrote:
> >> On 12.06.23 09:10, Kasireddy, Vivek wrote:
> >>> Sorry for the late reply; I just got back from vacation.
> >>> If it is unsafe to directly use the subpages of a hugetlb page, then
> >>> reverting
> >>>
On 13.06.23 10:26, Kasireddy, Vivek wrote:
Hi David,
On 12.06.23 09:10, Kasireddy, Vivek wrote:
Hi Mike,
Hi Vivek,
Sorry for the late reply; I just got back from vacation.
If it is unsafe to directly use the subpages of a hugetlb page, then reverting
this patch seems like the only option
From: Kasireddy, Vivek
> Sent: 13 June 2023 09:26
...
> > Is my understanding correct, that we can effectively long-term pin
> > (worse than mlock) 64 MiB per UDMABUF_CREATE, allowing eventually !root
> > users
>
> The 64 MiB limit is the theoretical upper bound that we have not seen hit in
> prac
Hi David,
>
> On 12.06.23 09:10, Kasireddy, Vivek wrote:
> > Hi Mike,
>
> Hi Vivek,
>
> >
> > Sorry for the late reply; I just got back from vacation.
> > If it is unsafe to directly use the subpages of a hugetlb page, then
> > reverting
> > this patch seems like the only option for addressing
On 12.06.23 09:10, Kasireddy, Vivek wrote:
Hi Mike,
Hi Vivek,
Sorry for the late reply; I just got back from vacation.
If it is unsafe to directly use the subpages of a hugetlb page, then reverting
this patch seems like the only option for addressing this issue immediately.
So, this patch is
Hi Mike,
Sorry for the late reply; I just got back from vacation.
If it is unsafe to directly use the subpages of a hugetlb page, then reverting
this patch seems like the only option for addressing this issue immediately.
So, this patch is
Acked-by: Vivek Kasireddy
As far as the use-case is conc
On Thu, Jun 08, 2023 at 01:49:27PM -0700, Mike Kravetz wrote:
> This effectively reverts commit 16c243e99d33 ("udmabuf: Add support
> for mapping hugepages (v4)"). Recently, Junxiao Chang found a BUG
> with page map counting as described here [1]. This issue pointed out
> that the udmabuf driver
This effectively reverts commit 16c243e99d33 ("udmabuf: Add support
for mapping hugepages (v4)"). Recently, Junxiao Chang found a BUG
with page map counting as described here [1]. This issue pointed out
that the udmabuf driver was making direct use of subpages of hugetlb
pages. This is not a goo
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