Messages in this thread | | | Date | Fri, 24 Aug 2012 15:01:54 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2] mm: hugetlb: add arch hook for clearing page flags before entering pool |
| |
On Thu, 23 Aug 2012 18:36:02 +0100 Will Deacon <will.deacon@arm.com> wrote:
> On Thu, Aug 23, 2012 at 06:11:56PM +0100, Michal Hocko wrote: > > On Thu 23-08-12 17:37:13, Will Deacon wrote: > > > The core page allocator ensures that page flags are zeroed when freeing > > > pages via free_pages_check. A number of architectures (ARM, PPC, MIPS) > > > rely on this property to treat new pages as dirty with respect to the > > > data cache and perform the appropriate flushing before mapping the pages > > > into userspace. > > > > > > This can lead to cache synchronisation problems when using hugepages, > > > since the allocator keeps its own pool of pages above the usual page > > > allocator and does not reset the page flags when freeing a page into > > > the pool. > > > > > > This patch adds a new architecture hook, arch_clear_hugepage_flags, so > > > that architectures which rely on the page flags being in a particular > > > state for fresh allocations can adjust the flags accordingly when a > > > page is freed into the pool.
You could have used __weak here quite neatly, but whatever.
> Next step: start posting the ARM code!
I suggest you keep this patch in whichever tree holds that arm code. If I see this patch turn up in linux-next then I'll just drop my copy, expecting that this patch will be merged alongside the ARM changes.
| |