Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=34bbd704051c9d053d69e90569a3a2365f4c7b50
Commit: 34bbd704051c9d053d69e90569a3a2365f4c7b50
Parent: 48dba8ab9b93c3b6b57946bd45ae013402b0b054
Author: Oleg Nesterov <[EMAIL PROTECTED]>
AuthorDate: Wed Feb 28 20:13:49 2007 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Mar 1 14:53:39 2007 -0800
[PATCH] adapt page_lock_anon_vma() to PREEMPT_RCU
page_lock_anon_vma() uses spin_lock() to block RCU. This doesn't work with
PREEMPT_RCU, we have to do rcu_read_lock() explicitely. Otherwise, it is
theoretically possible that slab returns anon_vma's memory to the system
before we do spin_unlock(&anon_vma->lock).
[ Hugh points out that this only matters for PREEMPT_RCU, which isn't merged
yet, and may never be. Regardless, this patch is conceptually the
right thing to do, even if it doesn't matter at this point. - Linus ]
Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]>
Cc: Paul McKenney <[EMAIL PROTECTED]>
Cc: Nick Piggin <[EMAIL PROTECTED]>
Cc: Christoph Lameter <[EMAIL PROTECTED]>
Acked-by: Hugh Dickins <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
mm/rmap.c | 17 +++++++++++++----
1 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c
index 669acb2..22ed3f7 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -183,7 +183,7 @@ void __init anon_vma_init(void)
*/
static struct anon_vma *page_lock_anon_vma(struct page *page)
{
- struct anon_vma *anon_vma = NULL;
+ struct anon_vma *anon_vma;
unsigned long anon_mapping;
rcu_read_lock();
@@ -195,9 +195,16 @@ static struct anon_vma *page_lock_anon_vma(struct page
*page)
anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
spin_lock(&anon_vma->lock);
+ return anon_vma;
out:
rcu_read_unlock();
- return anon_vma;
+ return NULL;
+}
+
+static void page_unlock_anon_vma(struct anon_vma *anon_vma)
+{
+ spin_unlock(&anon_vma->lock);
+ rcu_read_unlock();
}
/*
@@ -333,7 +340,8 @@ static int page_referenced_anon(struct page *page)
if (!mapcount)
break;
}
- spin_unlock(&anon_vma->lock);
+
+ page_unlock_anon_vma(anon_vma);
return referenced;
}
@@ -802,7 +810,8 @@ static int try_to_unmap_anon(struct page *page, int
migration)
if (ret == SWAP_FAIL || !page_mapped(page))
break;
}
- spin_unlock(&anon_vma->lock);
+
+ page_unlock_anon_vma(anon_vma);
return ret;
}
-
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