Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH] Add notification of page becoming writable to VMA ops | Date | Tue, 25 Oct 2005 11:12:19 +0100 |
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Hugh Dickins <hugh@veritas.com> wrote:
> > + if (vma->vm_ops->page_mkwrite && > > + vma->vm_ops->page_mkwrite(vma, new_page) < 0) > > + return VM_FAULT_SIGBUS; > > + } > > } > > This isn't necessarily wrong, and may be exactly how it was before, > I don't remember. But it implies that when page_mkwrite fails, > it page_cache_releases the page. Is that desirable? Or should > that be left to the caller?
You're right. I've added a release. That may explain a memory leak I was seeing that I couldn't find.
> > @@ -1945,7 +1998,7 @@ static int do_file_page(struct mm_struct > > Drop all those changes to do_file_page (which I added), they're no > longer necessary. A case appeared which made it clear that we cannot > rely on resolving this issue for get_user_pages in a single call to > handle_mm_fault, and that's why the VM_FAULT_WRITE stuff got added.
I take it then that:
(1) the write_access parameter to do_file_page() is there purely so that handle_pte_fault() can jump to it rather than calling it since they have the same parameter set and return value;
(2) and that do_file_page() always installs a read-only PTE so that do_wp_page() will be called subsequently on a write attempt.
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