Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760520AbaLLG0s (ORCPT ); Fri, 12 Dec 2014 01:26:48 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51974 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759337AbaLLGQ7 (ORCPT ); Fri, 12 Dec 2014 01:16:59 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Andrea Arcangeli" , "Linus Torvalds" , "Kirill A. Shutemov" , "David Rientjes" , "Suleiman Souhlal" Date: Fri, 12 Dec 2014 06:14:25 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 094/164] mm, thp: fix collapsing of hugepages on madvise In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:c97:8151:cc89:c28d X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.65-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: David Rientjes commit 6d50e60cd2edb5a57154db5a6f64eef5aa59b751 upstream. If an anonymous mapping is not allowed to fault thp memory and then madvise(MADV_HUGEPAGE) is used after fault, khugepaged will never collapse this memory into thp memory. This occurs because the madvise(2) handler for thp, hugepage_madvise(), clears VM_NOHUGEPAGE on the stack and it isn't stored in vma->vm_flags until the final action of madvise_behavior(). This causes the khugepaged_enter_vma_merge() to be a no-op in hugepage_madvise() when the vma had previously had VM_NOHUGEPAGE set. Fix this by passing the correct vma flags to the khugepaged mm slot handler. There's no chance khugepaged can run on this vma until after madvise_behavior() returns since we hold mm->mmap_sem. It would be possible to clear VM_NOHUGEPAGE directly from vma->vm_flags in hugepage_advise(), but I didn't want to introduce special case behavior into madvise_behavior(). I think it's best to just let it always set vma->vm_flags itself. Signed-off-by: David Rientjes Reported-by: Suleiman Souhlal Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings --- include/linux/khugepaged.h | 17 ++++++++++------- mm/huge_memory.c | 11 ++++++----- mm/mmap.c | 8 ++++---- 3 files changed, 20 insertions(+), 16 deletions(-) --- a/include/linux/khugepaged.h +++ b/include/linux/khugepaged.h @@ -6,7 +6,8 @@ #ifdef CONFIG_TRANSPARENT_HUGEPAGE extern int __khugepaged_enter(struct mm_struct *mm); extern void __khugepaged_exit(struct mm_struct *mm); -extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma); +extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma, + unsigned long vm_flags); #define khugepaged_enabled() \ (transparent_hugepage_flags & \ @@ -35,13 +36,13 @@ static inline void khugepaged_exit(struc __khugepaged_exit(mm); } -static inline int khugepaged_enter(struct vm_area_struct *vma) +static inline int khugepaged_enter(struct vm_area_struct *vma, + unsigned long vm_flags) { if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags)) if ((khugepaged_always() || - (khugepaged_req_madv() && - vma->vm_flags & VM_HUGEPAGE)) && - !(vma->vm_flags & VM_NOHUGEPAGE)) + (khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) && + !(vm_flags & VM_NOHUGEPAGE)) if (__khugepaged_enter(vma->vm_mm)) return -ENOMEM; return 0; @@ -54,11 +55,13 @@ static inline int khugepaged_fork(struct static inline void khugepaged_exit(struct mm_struct *mm) { } -static inline int khugepaged_enter(struct vm_area_struct *vma) +static inline int khugepaged_enter(struct vm_area_struct *vma, + unsigned long vm_flags) { return 0; } -static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma) +static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma, + unsigned long vm_flags) { return 0; } --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -682,7 +682,7 @@ int do_huge_pmd_anonymous_page(struct mm if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { if (unlikely(anon_vma_prepare(vma))) return VM_FAULT_OOM; - if (unlikely(khugepaged_enter(vma))) + if (unlikely(khugepaged_enter(vma, vma->vm_flags))) return VM_FAULT_OOM; page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), vma, haddr, numa_node_id(), 0); @@ -1493,7 +1493,7 @@ int hugepage_madvise(struct vm_area_stru * register it here without waiting a page fault that * may not happen any time soon. */ - if (unlikely(khugepaged_enter_vma_merge(vma))) + if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) return -ENOMEM; break; case MADV_NOHUGEPAGE: @@ -1625,7 +1625,8 @@ int __khugepaged_enter(struct mm_struct return 0; } -int khugepaged_enter_vma_merge(struct vm_area_struct *vma) +int khugepaged_enter_vma_merge(struct vm_area_struct *vma, + unsigned long vm_flags) { unsigned long hstart, hend; if (!vma->anon_vma) @@ -1641,11 +1642,11 @@ int khugepaged_enter_vma_merge(struct vm * If is_pfn_mapping() is true is_learn_pfn_mapping() must be * true too, verify it here. */ - VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); + VM_BUG_ON(is_linear_pfn_mapping(vma) || vm_flags & VM_NO_THP); hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; hend = vma->vm_end & HPAGE_PMD_MASK; if (hstart < hend) - return khugepaged_enter(vma); + return khugepaged_enter(vma, vm_flags); return 0; } --- a/mm/mmap.c +++ b/mm/mmap.c @@ -796,7 +796,7 @@ struct vm_area_struct *vma_merge(struct end, prev->vm_pgoff, NULL); if (err) return NULL; - khugepaged_enter_vma_merge(prev); + khugepaged_enter_vma_merge(prev, vm_flags); return prev; } @@ -815,7 +815,7 @@ struct vm_area_struct *vma_merge(struct next->vm_pgoff - pglen, NULL); if (err) return NULL; - khugepaged_enter_vma_merge(area); + khugepaged_enter_vma_merge(area, vm_flags); return area; } @@ -1741,7 +1741,7 @@ int expand_upwards(struct vm_area_struct } } vma_unlock_anon_vma(vma); - khugepaged_enter_vma_merge(vma); + khugepaged_enter_vma_merge(vma, vma->vm_flags); return error; } #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ @@ -1792,7 +1792,7 @@ int expand_downwards(struct vm_area_stru } } vma_unlock_anon_vma(vma); - khugepaged_enter_vma_merge(vma); + khugepaged_enter_vma_merge(vma, vma->vm_flags); return error; } -- 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/