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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
parent940e7da5163029978c2f6b5bbe213607add59062 (diff)
downloadlinux-linaro-stable-bebeb3d68b24bb4132d452c5707fe321208bcbcd.tar.gz
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')
-rw-r--r--mm/mlock.c17
-rw-r--r--mm/mmap.c20
-rw-r--r--mm/nommu.c5
-rw-r--r--mm/util.c6
4 files changed, 35 insertions, 13 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
index c9bd528b01d2..a296a49865df 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -416,7 +416,14 @@ static int do_mlock(unsigned long start, size_t len, int on)
return error;
}
-static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
+/*
+ * __mm_populate - populate and/or mlock pages within a range of address space.
+ *
+ * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
+ * flags. VMAs must be already marked with the desired vm_flags, and
+ * mmap_sem must not be held.
+ */
+int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
{
struct mm_struct *mm = current->mm;
unsigned long end, nstart, nend;
@@ -498,7 +505,7 @@ SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
error = do_mlock(start, len, 1);
up_write(&current->mm->mmap_sem);
if (!error)
- error = do_mlock_pages(start, len, 0);
+ error = __mm_populate(start, len, 0);
return error;
}
@@ -564,10 +571,8 @@ SYSCALL_DEFINE1(mlockall, int, flags)
capable(CAP_IPC_LOCK))
ret = do_mlockall(flags);
up_write(&current->mm->mmap_sem);
- if (!ret && (flags & MCL_CURRENT)) {
- /* Ignore errors */
- do_mlock_pages(0, TASK_SIZE, 1);
- }
+ if (!ret && (flags & MCL_CURRENT))
+ mm_populate(0, TASK_SIZE);
out:
return ret;
}
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);
diff --git a/mm/nommu.c b/mm/nommu.c
index b20db4e22263..7296a5a280e7 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1250,7 +1250,8 @@ unsigned long do_mmap_pgoff(struct file *file,
unsigned long len,
unsigned long prot,
unsigned long flags,
- unsigned long pgoff)
+ unsigned long pgoff,
+ bool *populate)
{
struct vm_area_struct *vma;
struct vm_region *region;
@@ -1260,6 +1261,8 @@ unsigned long do_mmap_pgoff(struct file *file,
kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
+ *populate = false;
+
/* decide whether we should attempt the mapping, and if so what sort of
* mapping */
ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
diff --git a/mm/util.c b/mm/util.c
index c55e26b17d93..13467e043e9e 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -355,12 +355,16 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
{
unsigned long ret;
struct mm_struct *mm = current->mm;
+ bool populate;
ret = security_mmap_file(file, prot, flag);
if (!ret) {
down_write(&mm->mmap_sem);
- ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff);
+ ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
+ &populate);
up_write(&mm->mmap_sem);
+ if (!IS_ERR_VALUE(ret) && populate)
+ mm_populate(ret, len);
}
return ret;
}