From bebeb3d68b24bb4132d452c5707fe321208bcbcd Mon Sep 17 00:00:00 2001 From: Michel Lespinasse Date: Fri, 22 Feb 2013 16:32:37 -0800 Subject: 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 Reported-by: Andy Lutomirski Acked-by: Rik van Riel Tested-by: Andy Lutomirski Cc: Greg Ungerer Cc: David Howells Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mlock.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) (limited to 'mm/mlock.c') 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(¤t->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(¤t->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; } -- cgit v1.2.3-59-g8ed1b