Messages in this thread | | | Date | Thu, 8 Oct 2009 11:37:52 +0200 | From | Johannes Weiner <> | Subject | Re: [PATCH v2][RFC] add MAP_UNLOCKED mmap flag |
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On Tue, Oct 06, 2009 at 08:53:44PM +0200, Gleb Natapov wrote: > On Tue, Oct 06, 2009 at 08:34:36PM +0200, Johannes Weiner wrote: > > On Tue, Oct 06, 2009 at 07:02:18PM +0200, Gleb Natapov wrote: > > > diff --git a/include/asm-generic/mman.h b/include/asm-generic/mman.h > > > index 32c8bd6..59e0f29 100644 > > > --- a/include/asm-generic/mman.h > > > +++ b/include/asm-generic/mman.h > > > @@ -12,6 +12,7 @@ > > > #define MAP_NONBLOCK 0x10000 /* do not block on IO */ > > > #define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */ > > > #define MAP_HUGETLB 0x40000 /* create a huge page mapping */ > > > +#define MAP_UNLOCKED 0x80000 /* force page unlocking */ > > > > > > #define MCL_CURRENT 1 /* lock all current mappings */ > > > #define MCL_FUTURE 2 /* lock all future mappings */ > > > diff --git a/mm/mmap.c b/mm/mmap.c > > > index 73f5e4b..7c2abdb 100644 > > > --- a/mm/mmap.c > > > +++ b/mm/mmap.c > > > @@ -985,6 +985,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, > > > if (!can_do_mlock()) > > > return -EPERM; > > > > > > + if (flags & MAP_UNLOKED) > > > + vm_flags &= ~VM_LOCKED; > > > Should we do something special about (MAP_UNLOCKED | MAP_LOCKED)? > > It is simpler to just ignore it. What do you think?
I think we should filter it out. It's unlocking even when MAP_LOCKED is set and doing mlock-specific checks also no mlock will happen.
Hannes
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