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Commit 5ea80f76 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

This reverts commit df54d6fa.

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: default avatarJeff Shorey <shoreyjeff@gmail.com>
Cc: Radu Caragea <sinaelgl@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d936d2d4

arch/x86/kernel/sys_x86_64.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

}

arch/x86/mm/mmap.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/sched.h

+0 −1
Original line number Diff line number Diff line
@@ -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,