Have any influence on set_memory_** about below patch ??

On 2016/1/13 19:18, Mark Rutland wrote:

On Wed, Jan 13, 2016 at 06:30:06PM +0800, Xishi Qiu wrote:

quoted

Hi Mark,

If I create swapper page tables by 4kb, not large page, then I use
set_memory_ro() to change the pate table flag, does it have the problem
too?

The splitting/merging problem would not apply.

However, you're going to waste a reasonable amount of memory by not
using section mappings in the swapper, and we gain additional complexity
in the page table setup code (which is shared with others things that
want section mappings).

What are you exactly actually trying to achieve?

If module allocates some pages and save data on them, and the data will
not be changed during the module running. So we want to use set_memory_ro()
to increase the security. If the data is changed, we can catch someone.

What memory do you want to mark RO, and why?

The key data, and it will not be changed during the running time.

quoted

From a previous discussion [1], we figured out alternative approaches

for common cases. Do none of those work for your case?

I have not read the patchset carefully, could you tell me the general meaning
of the approaches?

Thanks,
Xishi Qiu

Thanks,
Mark.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/397320.html

.