Revert "x86 get_unmapped_area(): use proper mmap base for bottom-up direction" (5ea80f76) · Commits · 戴 / test

This reverts commit . 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>

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,

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