Dne Út 10. května 2011 14:27:43 Michal Hocko napsal(a):
On Tue 10-05-11 10:40:37, Mel Gorman wrote:
On Fri, Apr 29, 2011 at 12:28:50PM +0200, Michal Hocko wrote:
On Thu 28-04-11 13:35:13, Jeff Mahoney wrote: [...]
Mel Gorman / Michal Hocko: - - patches.fixes/grab-swap-token-oops
There are still no in-kernel users of gup from kernel threads AFAICS. Besides that I think there is no issue in the current upstream because we do not get to handle_mm_fault (and grab_swap_token) path if there is no mm_struct. find_extend_vma will return NULL for (mm == NULL) and so we either go into gate_vma path (which is not handled by the patch and still can be an issue because of pgd_offset_gate) or fail with -EFAULT.
The same applies to openSUSE-11.4 and SLES10_SP4_BRANCH branches. If Mel doesn't see anything I would vote for dropping the patch from all supported branches.
That patch belongs to an SGI developer so there is a possibility that they have an RDMA driver or MPI accelerator that was doing direct writes to userspace after pinning the page with get_user_pages(). GPFS could also be doing weird things from kernel threads and pinning pages for IO a kernel thread context.
Then we should keep the patch. We shouldn't risk any "regression" even though they might be bugs in the external code. Thanks for the clarification I missed that 3rd party modules can really matter here.
That's completely true for the SLE products, but can't we drop it from the master branch? Then the "regression" will be discovered by partners in early alpha or beta phases of the next SLE product, which is the right way to deal with such features, IMO. Petr Tesarik L3 International -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-kernel+help@opensuse.org