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authorMichel Lespinasse <walken@google.com>2013-02-22 16:32:37 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-23 17:50:10 -0800
commitbebeb3d68b24bb4132d452c5707fe321208bcbcd (patch)
tree6e609cb7323fb1b4b7026fa0e35867145a181094 /mm/mmap.c
parent940e7da5163029978c2f6b5bbe213607add59062 (diff)
downloadlwn-bebeb3d68b24bb4132d452c5707fe321208bcbcd.tar.gz
lwn-bebeb3d68b24bb4132d452c5707fe321208bcbcd.zip
mm: introduce mm_populate() for populating new vmas
When creating new mappings using the MAP_POPULATE / MAP_LOCKED flags (or with MCL_FUTURE in effect), we want to populate the pages within the newly created vmas. This may take a while as we may have to read pages from disk, so ideally we want to do this outside of the write-locked mmap_sem region. This change introduces mm_populate(), which is used to defer populating such mappings until after the mmap_sem write lock has been released. This is implemented as a generalization of the former do_mlock_pages(), which accomplished the same task but was using during mlock() / mlockall(). Signed-off-by: Michel Lespinasse <walken@google.com> Reported-by: Andy Lutomirski <luto@amacapital.net> Acked-by: Rik van Riel <riel@redhat.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Cc: Greg Ungerer <gregungerer@westnet.com.au> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 09da0b264982..9b12e3047a86 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1154,12 +1154,15 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
- unsigned long flags, unsigned long pgoff)
+ unsigned long flags, unsigned long pgoff,
+ bool *populate)
{
struct mm_struct * mm = current->mm;
struct inode *inode;
vm_flags_t vm_flags;
+ *populate = false;
+
/*
* Does the application expect PROT_READ to imply PROT_EXEC?
*
@@ -1280,7 +1283,12 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
}
}
- return mmap_region(file, addr, len, flags, vm_flags, pgoff);
+ addr = mmap_region(file, addr, len, flags, vm_flags, pgoff);
+ if (!IS_ERR_VALUE(addr) &&
+ ((vm_flags & VM_LOCKED) ||
+ (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
+ *populate = true;
+ return addr;
}
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
@@ -1531,10 +1539,12 @@ out:
vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
if (vm_flags & VM_LOCKED) {
- if (!mlock_vma_pages_range(vma, addr, addr + len))
+ if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
+ vma == get_gate_vma(current->mm)))
mm->locked_vm += (len >> PAGE_SHIFT);
- } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
- make_pages_present(addr, addr + len);
+ else
+ vma->vm_flags &= ~VM_LOCKED;
+ }
if (file)
uprobe_mmap(vma);