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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 05:31:27 +0200
commit7cf46ba5d43e2596e559df7988eaf7ada966a6c8 (patch)
treefe3821f8073717f0613c5566e808e05873280c2c
parentfae5c27e842fef2c59ea3ab4a9afaf903cbd267e (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 03dfeb2e3928..4405e8804599 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -246,6 +246,20 @@ 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
@@ -257,13 +271,7 @@ 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 471e269536ae..3c18687e8c74 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 07da83f07712..fa2f1e68f4d1 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 *);
struct buffer_head *nilfs_btnode_create_block(struct address_space *btnc,
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 4d3ddcca305a..84dffd85b4c6 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 899a4d6985d4..d6b2ab57e54b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -637,6 +637,7 @@ 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
@@ -2148,6 +2149,7 @@ 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 e298c6f499bc..5df9a03087f5 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2459,6 +2459,7 @@ 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 */
@@ -2475,6 +2476,7 @@ 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);