From 47ed954900cca6220d0f58f220045e0765111af8 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 18 Mar 2015 13:42:38 -0400 Subject: [PATCH] parisc: mm: don't count preallocated pmds The patch 93fe92fd208c6998c8b56cc8bdbea87b44b9bfad that counts pmds allocated for a process introduced a bug on 64-bit PA-RISC kernels. The PA-RISC architecture preallocates one pmd with each pgd. This preallocated pmd can never be freed - pmd_free does nothing when it is called with this pmd. When the kernel attempts to free this preallocated pmd, it decreases the count of allocated pmds. The result is that the counter underflows and this error is reported. This patch fixes the bug by artifically incrementing the counter in pmd_free when the kernel tries to free the preallocated pmd. Signed-off-by: Mikulas Patocka Acked-by: Kirill A. Shutemov Signed-off-by: Helge Deller --- arch/parisc/include/asm/pgalloc.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/parisc/include/asm/pgalloc.h b/arch/parisc/include/asm/pgalloc.h index f213f5b4c4239..63e9ecae13103 100644 --- a/arch/parisc/include/asm/pgalloc.h +++ b/arch/parisc/include/asm/pgalloc.h @@ -74,8 +74,13 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd) { #ifdef CONFIG_64BIT if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED) - /* This is the permanent pmd attached to the pgd; - * cannot free it */ + /* + * This is the permanent pmd attached to the pgd; + * cannot free it. + * Increment the counter to compensate for the decrement + * done by generic mm code. + */ + mm_inc_nr_pmds(mm); return; #endif free_pages((unsigned long)pmd, PMD_ORDER); -- 2.39.5