Re: [v3] fs/proc/task_mmu: Implement IOCTL for efficient page table scanning

From: Paul Gofman
Date: Thu Jul 27 2023 - 13:15:54 EST


On Windows GetWriteWatch won't work if the range is not withing a single memory view regardless of MEM_LARGE_PAGES (that is, single VirtualAlloc result, somewhat analogous to VMA but not quite), such a call will result in an error.

For the context, Windows never auto splits or joins memory views, and basically nothing can be done across views boundary (merging placeholder views is an exception, while unrelated). VirtualProtect (which stands for mprotect) can be done for individual pages withing the view of course, but it is purely per page and doesn't affect view protection flags or result in any splitting of those. VirtualProtect across views adjacent in memory will also fail.

On 7/27/23 05:18, Michał Mirosław wrote:

Is it possible (on Windows) to have MEM_LARGE_PAGES allocation near a
normal one and run GetWriteWatch() on both in one call? If so, how
does it behave / what is expected?

Best Regards
Michał Mirosław