From patchwork Mon Jan 13 06:04:24 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aneesh Kumar K.V" X-Patchwork-Id: 309691 X-Patchwork-Delegate: benh@kernel.crashing.org Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [IPv6:::1]) by ozlabs.org (Postfix) with ESMTP id 45E152C00D0 for ; Mon, 13 Jan 2014 17:05:14 +1100 (EST) Received: from e28smtp03.in.ibm.com (e28smtp03.in.ibm.com [122.248.162.3]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id E79432C0081 for ; Mon, 13 Jan 2014 17:04:48 +1100 (EST) Received: from /spool/local by e28smtp03.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 13 Jan 2014 11:34:42 +0530 Received: from d28relay01.in.ibm.com (d28relay01.in.ibm.com [9.184.220.58]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id 697173940063 for ; Mon, 13 Jan 2014 11:34:41 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay01.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s0D64bnw50135162 for ; Mon, 13 Jan 2014 11:34:38 +0530 Received: from d28av01.in.ibm.com (localhost [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s0D64dIx010776 for ; Mon, 13 Jan 2014 11:34:40 +0530 Received: from skywalker.in.ibm.com (skywalker.in.ibm.com [9.124.35.175] (may be forged)) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id s0D64dqd010767; Mon, 13 Jan 2014 11:34:39 +0530 From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, paulus@samba.org, aarcange@redhat.com, kirill.shutemov@linux.intel.com Subject: [PATCH V4] powerpc: thp: Fix crash on mremap Date: Mon, 13 Jan 2014 11:34:24 +0530 Message-Id: <1389593064-32664-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.3.2 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14011306-3864-0000-0000-00000BEC09EA Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.16 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: "Aneesh Kumar K.V" 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 --- Changes from V3: * Drop "powerpc: mm: Move ppc64 page table range definitions to separate header"" patch 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(-) diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h index 4a191c472867..d27960c89a71 100644 --- 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_withdraw(struct mm_struct *mm, pmd_t *pmdp); #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_ */ diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index db0923458940..8e4f41d9af4d 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -558,6 +558,18 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp) } #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 diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 95d1acb0f3d2..5d80c53b87cb 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1502,19 +1502,15 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, 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: