From b30fe6c7ced70f62862c3d09357e7e8084e98d9f Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 11 Feb 2015 15:26:53 -0800 Subject: [PATCH] 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 Reported-by: Tyler Baker Tested-by: Tyler Baker Tested-by: Nishanth Menon Cc: Russell King Cc: James Hogan Cc: Guan Xuetao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-format-patch failed