diff options
| author | Michel Lespinasse <walken@google.com> | 2013-02-22 16:32:37 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-23 17:50:10 -0800 |
| commit | bebeb3d68b24bb4132d452c5707fe321208bcbcd (patch) | |
| tree | 6e609cb7323fb1b4b7026fa0e35867145a181094 /ipc/shm.c | |
| parent | 940e7da5163029978c2f6b5bbe213607add59062 (diff) | |
| download | lwn-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 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 4fa6d8fee730..9f047ba69e62 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(¤t->mm->mmap_sem); + if (populate) + mm_populate(addr, size); out_fput: fput(file); |