Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754500AbaBKUif (ORCPT ); Tue, 11 Feb 2014 15:38:35 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:39786 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753129AbaBKTGA (ORCPT ); Tue, 11 Feb 2014 14:06:00 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Aneesh Kumar K.V" , "Kirill A. Shutemov" , Benjamin Herrenschmidt Subject: [PATCH 3.13 110/120] powerpc/thp: Fix crash on mremap Date: Tue, 11 Feb 2014 11:05:51 -0800 Message-Id: <20140211184826.770819750@linuxfoundation.org> X-Mailer: git-send-email 1.8.5.1.163.gd7aced9 In-Reply-To: <20140211184823.492407127@linuxfoundation.org> References: <20140211184823.492407127@linuxfoundation.org> User-Agent: quilt/0.61-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Aneesh Kumar K.V" commit b3084f4db3aeb991c507ca774337c7e7893ed04f upstream. This patch fix the below crash NIP [c00000000004cee4] .__hash_page_thp+0x2a4/0x440 LR [c0000000000439ac] .hash_page+0x18c/0x5e0 ... Call Trace: [c000000736103c40] [00001ffffb000000] 0x1ffffb000000(unreliable) [437908.479693] [c000000736103d50] [c0000000000439ac] .hash_page+0x18c/0x5e0 [437908.479699] [c000000736103e30] [c00000000000924c] .do_hash_page+0x4c/0x58 On ppc64 we use the pgtable for storing the hpte slot information and store address to the pgtable at a constant offset (PTRS_PER_PMD) from pmd. On mremap, when we switch the pmd, we need to withdraw and deposit the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset from new pmd. We also want to move the withdraw and deposit before the set_pmd so that, when page fault find the pmd as trans huge we can be sure that pgtable can be located at the offset. Signed-off-by: Aneesh Kumar K.V Acked-by: Kirill A. Shutemov Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/pgtable-ppc64.h | 14 ++++++++++++++ include/asm-generic/pgtable.h | 12 ++++++++++++ mm/huge_memory.c | 14 +++++--------- 3 files changed, 31 insertions(+), 9 deletions(-) --- a/arch/powerpc/include/asm/pgtable-ppc64.h +++ b/arch/powerpc/include/asm/pgtable-ppc64.h @@ -558,5 +558,19 @@ extern pgtable_t pgtable_trans_huge_with #define __HAVE_ARCH_PMDP_INVALIDATE extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp); + +#define pmd_move_must_withdraw pmd_move_must_withdraw +typedef struct spinlock spinlock_t; +static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, + spinlock_t *old_pmd_ptl) +{ + /* + * Archs like ppc64 use pgtable to store per pmd + * specific information. So when we switch the pmd, + * we should also withdraw and deposit the pgtable + */ + return true; +} + #endif /* __ASSEMBLY__ */ #endif /* _ASM_POWERPC_PGTABLE_PPC64_H_ */ --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -558,6 +558,18 @@ static inline pmd_t pmd_read_atomic(pmd_ } #endif +#ifndef pmd_move_must_withdraw +static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, + spinlock_t *old_pmd_ptl) +{ + /* + * With split pmd lock we also need to move preallocated + * PTE page table if new_pmd is on different PMD page table. + */ + return new_pmd_ptl != old_pmd_ptl; +} +#endif + /* * This function is meant to be used by sites walking pagetables with * the mmap_sem hold in read mode to protect against MADV_DONTNEED and --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1502,19 +1502,15 @@ int move_huge_pmd(struct vm_area_struct spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); VM_BUG_ON(!pmd_none(*new_pmd)); - set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); - if (new_ptl != old_ptl) { - pgtable_t pgtable; - /* - * Move preallocated PTE page table if new_pmd is on - * different PMD page table. - */ + if (pmd_move_must_withdraw(new_ptl, old_ptl)) { + pgtable_t pgtable; pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); pgtable_trans_huge_deposit(mm, new_pmd, pgtable); - - spin_unlock(new_ptl); } + set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); + if (new_ptl != old_ptl) + spin_unlock(new_ptl); spin_unlock(old_ptl); } out: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/