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

This reverts commit df54d6fa54275ce59660453e29d1228c2b45a826.

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>

diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 48f8375e4c6b07edfbcefd819a8210f6e0839dfe..dbded5aedb818d511a46967ccb1d26d77233110f 100644 (file)
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -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;
        }
 }

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index f63778cb2363981ad8f98d0e068e4d789c2136b0..62c29a5bfe26aeb67bf63fb545294b79765e445f 100644 (file)
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -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;

diff --git a/include/linux/sched.h b/include/linux/sched.h
index e9995eb5985cd50b28aaae49f528487acf3f018c..078066daffd486d426027e9c97c3a40b8202e950 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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,