From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp09.au.ibm.com (e23smtp09.au.ibm.com [202.81.31.142]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 85C822C00A0 for ; Sat, 8 Feb 2014 00:52:13 +1100 (EST) Received: from /spool/local by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 7 Feb 2014 23:52:08 +1000 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [9.190.234.120]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 0B64B2CE8051 for ; Sat, 8 Feb 2014 00:52:06 +1100 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s17DWhWY3866956 for ; Sat, 8 Feb 2014 00:32:43 +1100 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s17Dq40T019216 for ; Sat, 8 Feb 2014 00:52:05 +1100 From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, paulus@samba.org, stable@vger.kernel.org Subject: [PATCH V2] powerpc: thp: Fix crash on mremap Date: Fri, 7 Feb 2014 19:21:57 +0530 Message-Id: <1391781117-19045-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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. variant of upstream SHA1: b3084f4db3aeb991c507ca774337c7e7893ed04f for 3.12 stable series Signed-off-by: Aneesh Kumar K.V --- arch/Kconfig | 3 +++ arch/powerpc/platforms/Kconfig.cputype | 1 + mm/huge_memory.c | 12 ++++++++++++ 3 files changed, 16 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index af2cc6eabcc7..bca9e7a18bd2 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -365,6 +365,9 @@ config HAVE_ARCH_TRANSPARENT_HUGEPAGE config HAVE_ARCH_SOFT_DIRTY bool +config ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW + bool + config HAVE_MOD_ARCH_SPECIFIC bool help diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype index 6704e2e20e6b..0225011231ea 100644 --- a/arch/powerpc/platforms/Kconfig.cputype +++ b/arch/powerpc/platforms/Kconfig.cputype @@ -71,6 +71,7 @@ config PPC_BOOK3S_64 select PPC_FPU select PPC_HAVE_PMU_SUPPORT select SYS_SUPPORTS_HUGETLBFS + select ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW select HAVE_ARCH_TRANSPARENT_HUGEPAGE if PPC_64K_PAGES config PPC_BOOK3E_64 diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 292a266e0d42..89b7a647f1cb 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1474,8 +1474,20 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, ret = __pmd_trans_huge_lock(old_pmd, vma); if (ret == 1) { +#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW + pgtable_t pgtable; +#endif pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); VM_BUG_ON(!pmd_none(*new_pmd)); +#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW + /* + * 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 + */ + pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); + pgtable_trans_huge_deposit(mm, new_pmd, pgtable); +#endif set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); spin_unlock(&mm->page_table_lock); } -- 1.8.3.2