NOMMU: Teach kobjsize() about VMA regions. (ab2e83ea) · Commits · e / devices / android_kernel_xiaomi_markw

Now that we no longer use compound pages for all large allocations, kobjsize() actively breaks things like binfmt_flat by always handing back PAGE_SIZE for mmap'ed regions. Fix this up by looking up the VMA region for non-compounds. Ideally binfmt_flat wants to get rid of kobjsize() completely, but this is an incremental step. Signed-off-by:

Paul Mundt <lethal@linux-sh.org> Signed-off-by:

David Howells <dhowells@redhat.com> Tested-by:

Mike Frysinger <vapier.adi@gmail.com>

mm/nommu.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -148,6 +148,20 @@ unsigned int kobjsize(const void *objp)
		if (PageSlab(page))
		return ksize(objp);

		/*
		* If it's not a compound page, see if we have a matching VMA
		* region. This test is intentionally done in reverse order,
		* so if there's no VMA, we still fall through and hand back
		* PAGE_SIZE for 0-order pages.
		*/
		if (!PageCompound(page)) {
		struct vm_area_struct *vma;

		vma = find_vma(current->mm, (unsigned long)objp);
		if (vma)
		return vma->vm_end - vma->vm_start;
		}

		/*
		* The ksize() function is only guaranteed to work for pointers
		* returned by kmalloc(). So handle arbitrary pointers here.