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authorMiklos Szeredi <mszeredi@suse.cz>2011-02-23 13:49:47 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2011-07-13 05:29:27 +0200
commitffdd12eabed263a487ddc05fdf65be6e4fc717b4 (patch)
tree1aa5afa34a1acf0deb2060e37b08d5ea10d3c651
parent453d61c441601d3f4ed9df7cfade4c5c35e98526 (diff)
mm: prevent concurrent unmap_mapping_range() on the same inode
commit 2aa15890f3c191326678f1bd68af61ec6b8753ec upstream. Michael Leun reported that running parallel opens on a fuse filesystem can trigger a "kernel BUG at mm/truncate.c:475" Gurudas Pai reported the same bug on NFS. The reason is, unmap_mapping_range() is not prepared for more than one concurrent invocation per inode. For example: thread1: going through a big range, stops in the middle of a vma and stores the restart address in vm_truncate_count. thread2: comes in with a small (e.g. single page) unmap request on the same vma, somewhere before restart_address, finds that the vma was already unmapped up to the restart address and happily returns without doing anything. Another scenario would be two big unmap requests, both having to restart the unmapping and each one setting vm_truncate_count to its own value. This could go on forever without any of them being able to finish. Truncate and hole punching already serialize with i_mutex. Other callers of unmap_mapping_range() do not, and it's difficult to get i_mutex protection for all callers. In particular ->d_revalidate(), which calls invalidate_inode_pages2_range() in fuse, may be called with or without i_mutex. This patch adds a new mutex to 'struct address_space' to prevent running multiple concurrent unmap_mapping_range() on the same mapping. [ We'll hopefully get rid of all this with the upcoming mm preemptibility series by Peter Zijlstra, the "mm: Remove i_mmap_mutex lockbreak" patch in particular. But that is for 2.6.39 ] Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reported-by: Michael Leun <lkml20101129@newton.leun.net> Reported-by: Gurudas Pai <gurudas.pai@oracle.com> Tested-by: Gurudas Pai <gurudas.pai@oracle.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--fs/inode.c22
-rw-r--r--fs/nilfs2/btnode.c13
-rw-r--r--fs/nilfs2/btnode.h1
-rw-r--r--fs/nilfs2/super.c2
-rw-r--r--include/linux/fs.h2
-rw-r--r--mm/memory.c2
6 files changed, 20 insertions, 22 deletions
diff --git a/fs/inode.c b/fs/inode.c
index 4d8e3be55976..8bbe00541e7f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -256,6 +256,20 @@ void destroy_inode(struct inode *inode)
kmem_cache_free(inode_cachep, (inode));
}
+void address_space_init_once(struct address_space *mapping)
+{
+ memset(mapping, 0, sizeof(*mapping));
+ INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
+ spin_lock_init(&mapping->tree_lock);
+ spin_lock_init(&mapping->i_mmap_lock);
+ INIT_LIST_HEAD(&mapping->private_list);
+ spin_lock_init(&mapping->private_lock);
+ INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
+ INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
+ mutex_init(&mapping->unmap_mutex);
+}
+EXPORT_SYMBOL(address_space_init_once);
+
/*
* These are initializations that only need to be done
* once, because the fields are idempotent across use
@@ -267,13 +281,7 @@ void inode_init_once(struct inode *inode)
INIT_HLIST_NODE(&inode->i_hash);
INIT_LIST_HEAD(&inode->i_dentry);
INIT_LIST_HEAD(&inode->i_devices);
- INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
- spin_lock_init(&inode->i_data.tree_lock);
- spin_lock_init(&inode->i_data.i_mmap_lock);
- INIT_LIST_HEAD(&inode->i_data.private_list);
- spin_lock_init(&inode->i_data.private_lock);
- INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
- INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
+ address_space_init_once(&inode->i_data);
i_size_ordered_init(inode);
#ifdef CONFIG_INOTIFY
INIT_LIST_HEAD(&inode->inotify_watches);
diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
index 84c25382f8e3..8dff3176111b 100644
--- a/fs/nilfs2/btnode.c
+++ b/fs/nilfs2/btnode.c
@@ -34,19 +34,6 @@
#include "btnode.h"
-void nilfs_btnode_cache_init_once(struct address_space *btnc)
-{
- memset(btnc, 0, sizeof(*btnc));
- INIT_RADIX_TREE(&btnc->page_tree, GFP_ATOMIC);
- spin_lock_init(&btnc->tree_lock);
- INIT_LIST_HEAD(&btnc->private_list);
- spin_lock_init(&btnc->private_lock);
-
- spin_lock_init(&btnc->i_mmap_lock);
- INIT_RAW_PRIO_TREE_ROOT(&btnc->i_mmap);
- INIT_LIST_HEAD(&btnc->i_mmap_nonlinear);
-}
-
static const struct address_space_operations def_btnode_aops = {
.sync_page = block_sync_page,
};
diff --git a/fs/nilfs2/btnode.h b/fs/nilfs2/btnode.h
index 3e2275172ed6..067913ea2b0e 100644
--- a/fs/nilfs2/btnode.h
+++ b/fs/nilfs2/btnode.h
@@ -37,7 +37,6 @@ struct nilfs_btnode_chkey_ctxt {
struct buffer_head *newbh;
};
-void nilfs_btnode_cache_init_once(struct address_space *);
void nilfs_btnode_cache_init(struct address_space *, struct backing_dev_info *);
void nilfs_btnode_cache_clear(struct address_space *);
int nilfs_btnode_submit_block(struct address_space *, __u64, sector_t,
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 63e7b108ff83..93c11af3562a 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -166,7 +166,7 @@ static void init_once(void *obj)
#ifdef CONFIG_NILFS_XATTR
init_rwsem(&ii->xattr_sem);
#endif
- nilfs_btnode_cache_init_once(&ii->i_btnode_cache);
+ address_space_init_once(&ii->i_btnode_cache);
ii->i_bmap = (struct nilfs_bmap *)&ii->i_bmap_union;
inode_init_once(&ii->vfs_inode);
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1ff096263b59..1b9a47abb014 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -635,6 +635,7 @@ struct address_space {
spinlock_t private_lock; /* for use by the address_space */
struct list_head private_list; /* ditto */
struct address_space *assoc_mapping; /* ditto */
+ struct mutex unmap_mutex; /* to protect unmapping */
} __attribute__((aligned(sizeof(long))));
/*
* On most architectures that alignment is already the case; but
@@ -2158,6 +2159,7 @@ extern loff_t vfs_llseek(struct file *file, loff_t offset, int origin);
extern int inode_init_always(struct super_block *, struct inode *);
extern void inode_init_once(struct inode *);
+extern void address_space_init_once(struct address_space *mapping);
extern void inode_add_to_lists(struct super_block *, struct inode *);
extern void iput(struct inode *);
extern struct inode * igrab(struct inode *);
diff --git a/mm/memory.c b/mm/memory.c
index 53c1da0d04a6..6c836d36f2f0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2454,6 +2454,7 @@ void unmap_mapping_range(struct address_space *mapping,
details.last_index = ULONG_MAX;
details.i_mmap_lock = &mapping->i_mmap_lock;
+ mutex_lock(&mapping->unmap_mutex);
spin_lock(&mapping->i_mmap_lock);
/* Protect against endless unmapping loops */
@@ -2470,6 +2471,7 @@ void unmap_mapping_range(struct address_space *mapping,
if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
spin_unlock(&mapping->i_mmap_lock);
+ mutex_unlock(&mapping->unmap_mutex);
}
EXPORT_SYMBOL(unmap_mapping_range);