linux/arch/unicore32
Kirill A. Shutemov b30fe6c7ce mm: fix false-positive warning on exit due mm_nr_pmds(mm)
The problem is that we check nr_ptes/nr_pmds in exit_mmap() which happens
*before* pgd_free().  And if an arch does pte/pmd allocation in
pgd_alloc() and frees them in pgd_free() we see offset in counters by the
time of the checks.

We tried to workaround this by offsetting expected counter value according
to FIRST_USER_ADDRESS for both nr_pte and nr_pmd in exit_mmap().  But it
doesn't work in some cases:

1. ARM with LPAE enabled also has non-zero USER_PGTABLES_CEILING, but
   upper addresses occupied with huge pmd entries, so the trick with
   offsetting expected counter value will get really ugly: we will have
   to apply it nr_pmds, but not nr_ptes.

2. Metag has non-zero FIRST_USER_ADDRESS, but doesn't do allocation
   pte/pmd page tables allocation in pgd_alloc(), just setup a pgd entry
   which is allocated at boot and shared accross all processes.

The proposal is to move the check to check_mm() which happens *after*
pgd_free() and do proper accounting during pgd_alloc() and pgd_free()
which would bring counters to zero if nothing leaked.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Tyler Baker <tyler.baker@linaro.org>
Tested-by: Tyler Baker <tyler.baker@linaro.org>
Tested-by: Nishanth Menon <nm@ti.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:04 -08:00
..
boot lib: Move fonts from drivers/video/console/ to lib/fonts/ 2013-06-28 10:28:22 +02:00
configs USB: delete CONFIG_USB_DEVICEFS from defconfig 2014-05-27 16:07:13 -07:00
include unicore32: drop pte_file()-related helpers 2015-02-10 14:30:33 -08:00
kernel nosave: consolidate __nosave_{begin,end} in <asm/sections.h> 2014-10-09 22:26:04 -04:00
lib unicore32: fix build error for find bitops 2011-11-15 17:13:14 +08:00
mm mm: fix false-positive warning on exit due mm_nr_pmds(mm) 2015-02-11 17:06:04 -08:00
.gitignore
Kconfig unicore32: Remove ARCH_HAS_CPUFREQ config option 2014-06-20 08:22:41 +08:00
Kconfig.debug unicore32: drop unused Kconfig symbols 2011-11-15 17:13:18 +08:00
Makefile unicore32: Use generic init_task 2012-05-05 13:00:26 +02:00