BACKPORT: FROMGIT: userfaultfd: hugetlbfs: only compile UFFD helpers if config enabled
For background, mm/userfaultfd.c provides a general mcopy_atomic
implementation. But some types of memory (i.e., hugetlb and shmem) need a
slightly different implementation, so they provide their own helpers for
this. In other words, userfaultfd is the only caller of these functions.
This patch achieves two things:
1. Don't spend time compiling code which will end up never being
referenced anyway (a small build time optimization).
2. In patches later in this series, we extend the signature of these
helpers with UFFD-specific state (a mode enumeration). Once this
happens, we *have to* either not compile the helpers, or
unconditionally define the UFFD-only state (which seems messier to me).
This includes the declarations in the headers, as otherwise they'd
yield warnings about implicitly defining the type of those arguments.
Link: https://lkml.kernel.org/r/20210301222728.176417-4-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Adam Ruprecht <ruprecht@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Cannon Matthews <cannonmatthews@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michal Koutn" <mkoutny@suse.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shawn Anastasio <shawn@anastas.io>
Cc: Steven Price <steven.price@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
(cherry picked from commit 0e6e243e1d9a252c047c4cb1b032cfb31caf87ea
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm)
Link: https://lore.kernel.org/patchwork/patch/1388133/
Conflicts: include/linux/hugetlb.h
(Manual rebase, required as 1f9dccb25b8fb48778149a002bb25d4ac2899633
isn't CP'ed)
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Bug: 160737021
Bug: 169683130
Change-Id: I765cff74cde5fb4ce8141fb95e41848890ced961
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index acdaf6c..3025fa1 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -108,11 +108,13 @@
unsigned long hugetlb_total_pages(void);
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags);
+#ifdef CONFIG_USERFAULTFD
int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
struct page **pagep);
+#endif /* CONFIG_USERFAULTFD */
int hugetlb_reserve_pages(struct inode *inode, long from, long to,
struct vm_area_struct *vma,
vm_flags_t vm_flags);
@@ -205,8 +207,10 @@
#define is_hugepage_only_range(mm, addr, len) 0
#define hugetlb_free_pgd_range(tlb, addr, end, floor, ceiling) ({BUG(); 0; })
#define hugetlb_fault(mm, vma, addr, flags) ({ BUG(); 0; })
+#ifdef CONFIG_USERFAULTFD
#define hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
src_addr, pagep) ({ BUG(); 0; })
+#endif /* CONFIG_USERFAULTFD */
#define huge_pte_offset(mm, address, sz) 0
static inline bool isolate_huge_page(struct page *page, struct list_head *list)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index af77e67..e0e4a1a 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4133,6 +4133,7 @@
return ret;
}
+#ifdef CONFIG_USERFAULTFD
/*
* Used by userfaultfd UFFDIO_COPY. Based on mcopy_atomic_pte with
* modifications for huge pages.
@@ -4273,6 +4274,7 @@
put_page(page);
goto out;
}
+#endif /* CONFIG_USERFAULTFD */
long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,