3.16.69-rc1 review patch. If anyone has any objections, please let me know.
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From: Oleg Nesterov oleg@redhat.com
commit b5330628546616af14ff23075fbf8d4ad91f6e25 upstream.
special_mapping_fault() is absolutely broken. It seems it was always wrong, but this didn't matter until vdso/vvar started to use more than one page.
And after this change vma_is_anonymous() becomes really trivial, it simply checks vm_ops == NULL. However, I do think the helper makes sense. There are a lot of ->vm_ops != NULL checks, the helper makes the caller's code more understandable (self-documented) and this is more grep-friendly.
This patch (of 3):
Preparation. Add the new simple helper, vma_is_anonymous(vma), and change handle_pte_fault() to use it. It will have more users.
The name is not accurate, say a hpet_mmap()'ed vma is not anonymous. Perhaps it should be named vma_has_fault() instead. But it matches the logic in mmap.c/memory.c (see next changes). "True" just means that a page fault will use do_anonymous_page().
Signed-off-by: Oleg Nesterov oleg@redhat.com Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Andy Lutomirski luto@kernel.org Cc: Hugh Dickins hughd@google.com Cc: Pavel Emelyanov xemul@parallels.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org [bwh: Backported to 3.16 as dependency of "mm/mincore.c: make mincore() more conservative"; adjusted context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- include/linux/mm.h | 5 +++++ mm/memory.c | 8 ++++---- 2 files changed, 9 insertions(+), 4 deletions(-)
--- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1241,6 +1241,11 @@ int get_cmdline(struct task_struct *task
int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t);
+static inline bool vma_is_anonymous(struct vm_area_struct *vma) +{ + return !vma->vm_ops; +} + extern unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long old_addr, struct vm_area_struct *new_vma, unsigned long new_addr, unsigned long len, --- a/mm/memory.c +++ b/mm/memory.c @@ -3105,12 +3105,12 @@ static int handle_pte_fault(struct mm_st entry = *pte; if (!pte_present(entry)) { if (pte_none(entry)) { - if (vma->vm_ops) + if (vma_is_anonymous(vma)) + return do_anonymous_page(mm, vma, address, + pte, pmd, flags); + else return do_fault(mm, vma, address, pte, pmd, flags, entry); - - return do_anonymous_page(mm, vma, address, - pte, pmd, flags); } return do_swap_page(mm, vma, address, pte, pmd, flags, entry);