lkml.org 
[lkml]   [2010]   [Jan]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[RFC][PATCH 6/8] mm: handle_speculative_fault()
Generic speculative fault handler, tries to service a pagefault
without holding mmap_sem.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/mm.h | 2 +
mm/memory.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 60 insertions(+), 1 deletion(-)
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -1998,7 +1998,7 @@ again:
if (!*ptep)
goto out;

- if (vma_is_dead(vma, seq))
+ if (vma && vma_is_dead(vma, seq))
goto unlock;

unpin_page_tables();
@@ -3112,6 +3112,63 @@ int handle_mm_fault(struct mm_struct *mm
return handle_pte_fault(mm, vma, address, entry, pmd, flags, 0);
}

+int handle_speculative_fault(struct mm_struct *mm, unsigned long address,
+ unsigned int flags)
+{
+ pmd_t *pmd = NULL;
+ pte_t *pte, entry;
+ spinlock_t *ptl;
+ struct vm_area_struct *vma;
+ unsigned int seq;
+ int ret = VM_FAULT_RETRY;
+ int dead;
+
+ __set_current_state(TASK_RUNNING);
+ flags |= FAULT_FLAG_SPECULATIVE;
+
+ count_vm_event(PGFAULT);
+
+ rcu_read_lock();
+ if (!pte_map_lock(mm, NULL, address, pmd, flags, 0, &pte, &ptl))
+ goto out_unlock;
+
+ vma = find_vma(mm, address);
+
+ if (!vma)
+ goto out_unmap;
+
+ dead = RB_EMPTY_NODE(&vma->vm_rb);
+ seq = vma->vm_sequence.sequence;
+ /*
+ * Matches both the wmb in write_seqcount_begin/end() and
+ * the wmb in detach_vmas_to_be_unmapped()/__unlink_vma().
+ */
+ smp_rmb();
+ if (dead || seq & 1)
+ goto out_unmap;
+
+ if (!(vma->vm_end > address && vma->vm_start <= address))
+ goto out_unmap;
+
+ if (read_seqcount_retry(&vma->vm_sequence, seq))
+ goto out_unmap;
+
+ entry = *pte;
+
+ pte_unmap_unlock(pte, ptl);
+
+ ret = handle_pte_fault(mm, vma, address, entry, pmd, flags, seq);
+
+out_unlock:
+ rcu_read_unlock();
+ return ret;
+
+out_unmap:
+ pte_unmap_unlock(pte, ptl);
+ goto out_unlock;
+}
+
+
#ifndef __PAGETABLE_PUD_FOLDED
/*
* Allocate page upper directory.
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -829,6 +829,8 @@ int invalidate_inode_page(struct page *p
#ifdef CONFIG_MMU
extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags);
+extern int handle_speculative_fault(struct mm_struct *mm,
+ unsigned long address, unsigned int flags);
#else
static inline int handle_mm_fault(struct mm_struct *mm,
struct vm_area_struct *vma, unsigned long address,
--



\
 
 \ /
  Last update: 2010-01-04 21:51    [from the cache]
©2003-2011 Jasper Spaans