Re: 2.6.23-mm1

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 17 Oct 2007 16:01:01 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> I noticed 32bit binary on x86_64 behavior is changed on 2.6.23-mm1.
> 
> This is a result of pmap after process returns -ENOMEM.(see attached program)
> == on 2.6.23 ==
> errno 12
> 3531:   ./malloc
> 0000000000001000   6272K -----    [ anon ]
> 0000000000621000    100K r-x--  /lib/ld-2.5.so
> 000000000063a000      4K r----  /lib/ld-2.5.so
> 000000000063b000      4K rw---  /lib/ld-2.5.so
> 000000000063c000      8K -----    [ anon ]
> 000000000063e000   1244K r-x--  /lib/libc-2.5.so
> 0000000000775000      8K r----  /lib/libc-2.5.so
> 0000000000777000      4K rw---  /lib/libc-2.5.so
> 0000000000778000     12K rw---    [ anon ]
> 000000000077b000 123700K -----    [ anon ]
> 0000000008048000      4K r-x--  /home/kamezawa/malloc
> 0000000008049000      4K rw---  /home/kamezawa/malloc
> 000000000804a000 3929824K -----    [ anon ]
> 00000000f7f02000      8K rw---    [ anon ]
> 00000000f7f04000    100K -----    [ anon ]
> 00000000f7f1d000      4K rw---    [ anon ]
> 00000000f7f1e000 131812K -----    [ anon ]
> 00000000fffd7000     84K rw---    [ stack ]
> 00000000fffec000     72K -----    [ anon ]
> 00000000ffffe000      4K r-x--    [ anon ]
>  total          4193272K
> ==
> 
> == on 2.6.23-mm1==
> errno 12
> 3504:   ./malloc
> 0000000000621000    100K r-x--  /lib/ld-2.5.so
> 000000000063a000      4K r----  /lib/ld-2.5.so
> 000000000063b000      4K rw---  /lib/ld-2.5.so
> 000000000063e000   1244K r-x--  /lib/libc-2.5.so
> 0000000000775000      8K r----  /lib/libc-2.5.so
> 0000000000777000      4K rw---  /lib/libc-2.5.so
> 0000000000778000     12K rw---    [ anon ]
> 0000000008048000      4K r-x--  /home/kamezawa/malloc
> 0000000008049000      4K rw---  /home/kamezawa/malloc
> 0000000055555000      4K rw---    [ anon ]
> 0000000055556000    100K -----    [ anon ]
> 000000005556f000      8K rw---    [ anon ]
> 0000000055671000 2789016K -----    [ anon ]
> 00000000ffa17000     84K rw---    [ stack ]
> 00000000ffa2c000   5960K -----    [ anon ]
> 00000000ffffe000      4K r-x--    [ anon ]
>  total          2796560K
> ==

So it only managed to allocate half as much virtual memory?  Lovely.
Thanks for the test case.

> Maybe get_unmapped_area() had some change.
> Is this intended ?

It had better not be.

It is due to pie-executable-randomization.patch.  That patch has been an
ongoing source of trouble.  I'll drop it.  Again.  Guys, please don't resend
it until it actually works.