From ffdd12eabed263a487ddc05fdf65be6e4fc717b4 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 23 Feb 2011 13:49:47 +0100 Subject: [PATCH] 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 Reported-by: Michael Leun Reported-by: Gurudas Pai Tested-by: Gurudas Pai Acked-by: Hugh Dickins Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/inode.c | 22 +++++++++++++++------- fs/nilfs2/btnode.c | 13 ------------- fs/nilfs2/btnode.h | 1 - fs/nilfs2/super.c | 2 +- include/linux/fs.h | 2 ++ mm/memory.c | 2 ++ 6 files changed, 20 insertions(+), 22 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 4d8e3be5597..8bbe00541e7 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 84c25382f8e..8dff3176111 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 3e2275172ed..067913ea2b0 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 63e7b108ff8..93c11af3562 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 1ff096263b5..1b9a47abb01 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 53c1da0d04a..6c836d36f2f 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); -- 2.11.4.GIT