Messages in this thread | | | Date | Thu, 24 Jun 2004 16:19:59 +0900 | From | IWAMOTO Toshihiro <> | Subject | Re: Atomic operation for physically moving a page (for memory defragmentation) |
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At Wed, 23 Jun 2004 13:56:30 -0700, Dave Hansen wrote: > > On Wed, 2004-06-23 at 04:59, Hirokazu Takahashi wrote: > > We should know that many part of kernel code will access the page > > without holding a lock_page(). The lock_page() can't block them. > > No, but it will block them from establishing a new PTE to the page. You > need to: > > 1. make sure no new PTEs can be established to the page > 2. make sure there are no valid PTEs to the page. > 3. do the move > > My suggestion relates to 1, only.
I wonder if you are talking exclusively about swap (anonymous) pages, where lock_page() might work.
(I wonder why lock_page() is needed in do_swap_page(), btw.)
For page caches, usually lock_page() cannot prevent accesses to them, and there are several kernel functions which don't need PTE mappings for access. One of such functions is do_generic_mapping_read().
-- IWAMOTO Toshihiro - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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