Revert "x86 get_unmapped_area(): use proper mmap base for bottom-up direction"

This reverts commit df54d6fa54.

The commit isn't necessarily wrong, but because it recalculates the
random mmap_base every time, it seems to confuse user memory allocators
that expect contiguous mmap allocations even when the mmap address isn't
specified.

In particular, the MATLAB Java runtime seems to be unhappy. See

  https://bugzilla.kernel.org/show_bug.cgi?id=60774

So we'll want to apply the random offset only once, and Radu has a patch
for that.  Revert this older commit in order to apply the other one.

Reported-by: Jeff Shorey <shoreyjeff@gmail.com>
Cc: Radu Caragea <sinaelgl@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2013-08-22 09:13:06 -07:00
parent d936d2d452
commit 5ea80f76a5
3 changed files with 2 additions and 3 deletions

View file

@ -101,7 +101,7 @@ static void find_start_end(unsigned long flags, unsigned long *begin,
*begin = new_begin;
}
} else {
*begin = mmap_legacy_base();
*begin = TASK_UNMAPPED_BASE;
*end = TASK_SIZE;
}
}

View file

@ -98,7 +98,7 @@ static unsigned long mmap_base(void)
* Bottom-up (legacy) layout on X86_32 did not support randomization, X86_64
* does, but not when emulating X86_32
*/
unsigned long mmap_legacy_base(void)
static unsigned long mmap_legacy_base(void)
{
if (mmap_is_ia32())
return TASK_UNMAPPED_BASE;

View file

@ -314,7 +314,6 @@ struct nsproxy;
struct user_namespace;
#ifdef CONFIG_MMU
extern unsigned long mmap_legacy_base(void);
extern void arch_pick_mmap_layout(struct mm_struct *mm);
extern unsigned long
arch_get_unmapped_area(struct file *, unsigned long, unsigned long,