Re: mm: BUG in unmap_page_range
From: Aneesh Kumar K.V <hidden>
Date: 2014-08-06 07:15:03
Also in:
linux-mm, lkml
Mel Gorman [off-list ref] writes:
From d0c77a2b497da46c52792ead066d461e5111a594 Mon Sep 17 00:00:00 2001 From: Mel Gorman <mgorman@suse.de> Date: Tue, 5 Aug 2014 12:06:50 +0100 Subject: [PATCH] mm: Remove misleading ARCH_USES_NUMA_PROT_NONE ARCH_USES_NUMA_PROT_NONE was defined for architectures that implemented _PAGE_NUMA using _PROT_NONE. This saved using an additional PTE bit and relied on the fact that PROT_NONE vmas were skipped by the NUMA hinting fault scanner. This was found to be conceptually confusing with a lot of implicit assumptions and it was asked that an alternative be found. Commit c46a7c81 "x86: define _PAGE_NUMA by reusing software bits on the PMD and PTE levels" redefined _PAGE_NUMA on x86 to be one of the swap PTE bits and shrunk the maximum possible swap size but it did not go far enough. There are no architectures that reuse _PROT_NONE as _PROT_NUMA but the relics still exist. This patch removes ARCH_USES_NUMA_PROT_NONE and removes some unnecessary duplication in powerpc vs the generic implementation by defining the types the core NUMA helpers expected to exist from x86 with their ppc64 equivalent. The unification for ppc64 is less than ideal because types do not exist that the "generic" code expects to. This patch works around the problem but it would be preferred if the powerpc people would look at this to see if they have opinions on what might suit them better. Signed-off-by: Mel Gorman <mgorman@suse.de> --- arch/powerpc/include/asm/pgtable.h | 55 ++++++++------------------------------ arch/x86/Kconfig | 1 - include/asm-generic/pgtable.h | 35 ++++++++++++------------ init/Kconfig | 11 -------- 4 files changed, 29 insertions(+), 73 deletions(-)
....
quoted hunk
- #define pmdp_set_numa pmdp_set_numa static inline void pmdp_set_numa(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp)@@ -109,16 +71,21 @@ static inline void pmdp_set_numa(struct mm_struct *mm, unsigned long addr, return; } -#define pmd_mknonnuma pmd_mknonnuma -static inline pmd_t pmd_mknonnuma(pmd_t pmd) +/* + * Generic NUMA pte helpers expect pteval_t and pmdval_t types to exist + * which was inherited from x86. For the purposes of powerpc pte_basic_t is + * equivalent + */ +#define pteval_t pte_basic_t +#define pmdval_t pmd_t +static inline pteval_t pte_flags(pte_t pte) { - return pte_pmd(pte_mknonnuma(pmd_pte(pmd))); + return pte_val(pte) & PAGE_PROT_BITS;
PAGE_PROT_BITS don't get the _PAGE_NUMA and _PAGE_PRESENT. I will have to check further to find out why the mask doesn't include _PAGE_PRESENT.
}
-#define pmd_mknuma pmd_mknuma
-static inline pmd_t pmd_mknuma(pmd_t pmd)
+static inline pteval_t pmd_flags(pte_t pte)
{static inline pmdval_t ?
- return pte_pmd(pte_mknuma(pmd_pte(pmd))); + return pmd_val(pte) & PAGE_PROT_BITS; }
-aneesh