Messages in this thread | | | Date | Thu, 12 Feb 2015 13:59:22 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH 2/4] mm: rename __mlock_vma_pages_range() to populate_vma_page_range() |
| |
On Thu, 12 Feb 2015, Kirill A. Shutemov wrote:
> > I think it makes sense to drop the references about "downgrading" > > mm->mmap_sem in the documentation since populate_vma_page_range() can be > > called with it held either for read or write depending on the context. > > I'm not sure what references you're talking about. > > Is it about this part: > > * If @nonblocking is non-NULL, it must held for read only and may be > * released. If it's released, *@nonblocking will be set to 0. > > ? >
No, I was agreeing with your removal from the documentation:
@@ -463,21 +463,11 @@ populate the page table.
To mlock a range of memory under the unevictable/mlock infrastructure, the mmap() handler and task address space expansion functions call -mlock_vma_pages_range() specifying the vma and the address range to mlock. -mlock_vma_pages_range() filters VMAs like mlock_fixup(), as described above in -"Filtering Special VMAs". It will clear the VM_LOCKED flag, which will have -already been set by the caller, in filtered VMAs. Thus these VMA's need not be -visited for munlock when the region is unmapped. - -For "normal" VMAs, mlock_vma_pages_range() calls __mlock_vma_pages_range() to -fault/allocate the pages and mlock them. Again, like mlock_fixup(), -mlock_vma_pages_range() downgrades the mmap semaphore to read mode before -attempting to fault/allocate and mlock the pages and "upgrades" the semaphore -back to write mode before returning. - -The callers of mlock_vma_pages_range() will have already added the memory range +populate_vma_page_range() specifying the vma and the address range to mlock. + +The callers of populate_vma_page_range() will have already added the memory range to be mlocked to the task's "locked_vm". To account for filtered VMAs, -mlock_vma_pages_range() returns the number of pages NOT mlocked. All of the +populate_vma_page_range() returns the number of pages NOT mlocked. All of the callers then subtract a non-negative return value from the task's locked_vm. A negative return value represent an error - for example, from get_user_pages() attempting to fault in a VMA with PROT_NONE access. In this case, we leave the
| |