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authorAndy Lutomirski <luto@amacapital.net>2015-12-29 20:12:19 -0800
committerIngo Molnar <mingo@kernel.org>2016-01-12 11:59:34 +0100
commitf872f5400cc01373d8e29d9c7a5296ccfaf4ccf3 (patch)
tree5874745ea7393545d7bb1a1d0dd3c7961dd59dd6 /mm/mmap.c
parentaa0421410fc540832f0fd267ff0f2657c3276053 (diff)
downloadlinux-f872f5400cc01373d8e29d9c7a5296ccfaf4ccf3.tar.bz2
mm: Add a vm_special_mapping.fault() method
Requiring special mappings to give a list of struct pages is inflexible: it prevents sane use of IO memory in a special mapping, it's inefficient (it requires arch code to initialize a list of struct pages, and it requires the mm core to walk the entire list just to figure out how long it is), and it prevents arch code from doing anything fancy when a special mapping fault occurs. Add a .fault method as an alternative to filling in a .pages array. Looks-OK-to: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a26d1677c0bc7e774c33f469451a78ca31e9e6af.1451446564.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 2ce04a649f6b..f717453b1a57 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3030,11 +3030,16 @@ static int special_mapping_fault(struct vm_area_struct *vma,
pgoff_t pgoff;
struct page **pages;
- if (vma->vm_ops == &legacy_special_mapping_vmops)
+ if (vma->vm_ops == &legacy_special_mapping_vmops) {
pages = vma->vm_private_data;
- else
- pages = ((struct vm_special_mapping *)vma->vm_private_data)->
- pages;
+ } else {
+ struct vm_special_mapping *sm = vma->vm_private_data;
+
+ if (sm->fault)
+ return sm->fault(sm, vma, vmf);
+
+ pages = sm->pages;
+ }
for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
pgoff--;