[PATCH] MAP_POPULATE prot 0

[PATCH] MAP_POPULATE prot 0

[Hugh Dickins]

It seems eccentric to implement MAP_POPULATE only on PROT_NONE mappings:
do_mmap_pgoff is passing down prot, then sys_remap_file_pages verifies
it's not set.  I guess that's an oversight from when we realized that
the prot arg to sys_remap_file_pages was misdesigned.

There's another oddity whose heritage is harder for me to understand,
so please let me leave it to you: sys_remap_file_pages is declared as
asmlinkage in mm/fremap.c, but is the one syscall declared without
asmlinkage in include/linux/syscalls.h.

Signed-off-by: Hugh Dickins <hugh@veritas.com>

--- 2.6.7-rc1/mm/mmap.c	2004-05-24 12:17:56.209179464 +0100
+++ linux/mm/mmap.c	2004-05-24 19:33:40.265678752 +0100
@@ -951,7 +951,7 @@ out:	
 	}
 	if (flags & MAP_POPULATE) {
 		up_write(&mm->mmap_sem);
-		sys_remap_file_pages(addr, len, prot,
+		sys_remap_file_pages(addr, len, 0,
 					pgoff, flags & MAP_NONBLOCK);
 		down_write(&mm->mmap_sem);
 	}

Re: [PATCH] MAP_POPULATE prot 0

[Ingo Molnar]

* Hugh Dickins <hugh@veritas.com> wrote:

> It seems eccentric to implement MAP_POPULATE only on PROT_NONE
> mappings: do_mmap_pgoff is passing down prot, then
> sys_remap_file_pages verifies it's not set.  I guess that's an
> oversight from when we realized that the prot arg to
> sys_remap_file_pages was misdesigned.

yeah.

> There's another oddity whose heritage is harder for me to understand,
> so please let me leave it to you: sys_remap_file_pages is declared as
> asmlinkage in mm/fremap.c, but is the one syscall declared without
> asmlinkage in include/linux/syscalls.h.

i think that's just an oversight.

	Ingo