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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 /ipc
parent940e7da5163029978c2f6b5bbe213607add59062 (diff)
downloadlinux-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 'ipc')
-rw-r--r--ipc/shm.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 4fa6d8fee73..9f047ba69e6 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -967,11 +967,11 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
unsigned long flags;
unsigned long prot;
int acc_mode;
- unsigned long user_addr;
struct ipc_namespace *ns;
struct shm_file_data *sfd;
struct path path;
fmode_t f_mode;
+ bool populate = false;
err = -EINVAL;
if (shmid < 0)
@@ -1070,13 +1070,15 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
goto invalid;
}
- user_addr = do_mmap_pgoff(file, addr, size, prot, flags, 0);
- *raddr = user_addr;
+ addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate);
+ *raddr = addr;
err = 0;
- if (IS_ERR_VALUE(user_addr))
- err = (long)user_addr;
+ if (IS_ERR_VALUE(addr))
+ err = (long)addr;
invalid:
up_write(&current->mm->mmap_sem);
+ if (populate)
+ mm_populate(addr, size);
out_fput:
fput(file);