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| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2019-08-21 18:05:55 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2019-09-09 15:59:14 +0300 |
| commit | 3acd48507dc43eeeb0a1fe965b8bad91cab904a7 (patch) | |
| tree | 5dd3e0e79f99ed6e28f36dc267ae7c22dbcba542 /fs/btrfs/inode.c | |
| parent | 62fdaa52a3d00a875da771719b6dc537ca79fce1 (diff) | |
| download | linux-3acd48507dc43eeeb0a1fe965b8bad91cab904a7.tar.xz | |
btrfs: fix allocation of free space cache v1 bitmap pages
Various notifications of type "BUG kmalloc-4096 () : Redzone
overwritten" have been observed recently in various parts of the kernel.
After some time, it has been made a relation with the use of BTRFS
filesystem and with SLUB_DEBUG turned on.
[ 22.809700] BUG kmalloc-4096 (Tainted: G W ): Redzone overwritten
[ 22.810286] INFO: 0xbe1a5921-0xfbfc06cd. First byte 0x0 instead of 0xcc
[ 22.810866] INFO: Allocated in __load_free_space_cache+0x588/0x780 [btrfs] age=22 cpu=0 pid=224
[ 22.811193] __slab_alloc.constprop.26+0x44/0x70
[ 22.811345] kmem_cache_alloc_trace+0xf0/0x2ec
[ 22.811588] __load_free_space_cache+0x588/0x780 [btrfs]
[ 22.811848] load_free_space_cache+0xf4/0x1b0 [btrfs]
[ 22.812090] cache_block_group+0x1d0/0x3d0 [btrfs]
[ 22.812321] find_free_extent+0x680/0x12a4 [btrfs]
[ 22.812549] btrfs_reserve_extent+0xec/0x220 [btrfs]
[ 22.812785] btrfs_alloc_tree_block+0x178/0x5f4 [btrfs]
[ 22.813032] __btrfs_cow_block+0x150/0x5d4 [btrfs]
[ 22.813262] btrfs_cow_block+0x194/0x298 [btrfs]
[ 22.813484] commit_cowonly_roots+0x44/0x294 [btrfs]
[ 22.813718] btrfs_commit_transaction+0x63c/0xc0c [btrfs]
[ 22.813973] close_ctree+0xf8/0x2a4 [btrfs]
[ 22.814107] generic_shutdown_super+0x80/0x110
[ 22.814250] kill_anon_super+0x18/0x30
[ 22.814437] btrfs_kill_super+0x18/0x90 [btrfs]
[ 22.814590] INFO: Freed in proc_cgroup_show+0xc0/0x248 age=41 cpu=0 pid=83
[ 22.814841] proc_cgroup_show+0xc0/0x248
[ 22.814967] proc_single_show+0x54/0x98
[ 22.815086] seq_read+0x278/0x45c
[ 22.815190] __vfs_read+0x28/0x17c
[ 22.815289] vfs_read+0xa8/0x14c
[ 22.815381] ksys_read+0x50/0x94
[ 22.815475] ret_from_syscall+0x0/0x38
Commit 69d2480456d1 ("btrfs: use copy_page for copying pages instead of
memcpy") changed the way bitmap blocks are copied. But allthough bitmaps
have the size of a page, they were allocated with kzalloc().
Most of the time, kzalloc() allocates aligned blocks of memory, so
copy_page() can be used. But when some debug options like SLAB_DEBUG are
activated, kzalloc() may return unaligned pointer.
On powerpc, memcpy(), copy_page() and other copying functions use
'dcbz' instruction which provides an entire zeroed cacheline to avoid
memory read when the intention is to overwrite a full line. Functions
like memcpy() are writen to care about partial cachelines at the start
and end of the destination, but copy_page() assumes it gets pages. As
pages are naturally cache aligned, copy_page() doesn't care about
partial lines. This means that when copy_page() is called with a
misaligned pointer, a few leading bytes are zeroed.
To fix it, allocate bitmaps through kmem_cache instead of using kzalloc()
The cache pool is created with PAGE_SIZE alignment constraint.
Reported-by: Erhard F. <erhard_f@mailbox.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204371
Fixes: 69d2480456d1 ("btrfs: use copy_page for copying pages instead of memcpy")
Cc: stable@vger.kernel.org # 4.19+
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: David Sterba <dsterba@suse.com>
[ rename to btrfs_free_space_bitmap ]
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/inode.c')
| -rw-r--r-- | fs/btrfs/inode.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b52282df8c4d..d79ad5abd06e 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -74,6 +74,7 @@ static struct kmem_cache *btrfs_inode_cachep; struct kmem_cache *btrfs_trans_handle_cachep; struct kmem_cache *btrfs_path_cachep; struct kmem_cache *btrfs_free_space_cachep; +struct kmem_cache *btrfs_free_space_bitmap_cachep; static int btrfs_setsize(struct inode *inode, struct iattr *attr); static int btrfs_truncate(struct inode *inode, bool skip_writeback); @@ -9409,6 +9410,7 @@ void __cold btrfs_destroy_cachep(void) kmem_cache_destroy(btrfs_trans_handle_cachep); kmem_cache_destroy(btrfs_path_cachep); kmem_cache_destroy(btrfs_free_space_cachep); + kmem_cache_destroy(btrfs_free_space_bitmap_cachep); } int __init btrfs_init_cachep(void) @@ -9438,6 +9440,12 @@ int __init btrfs_init_cachep(void) if (!btrfs_free_space_cachep) goto fail; + btrfs_free_space_bitmap_cachep = kmem_cache_create("btrfs_free_space_bitmap", + PAGE_SIZE, PAGE_SIZE, + SLAB_RED_ZONE, NULL); + if (!btrfs_free_space_bitmap_cachep) + goto fail; + return 0; fail: btrfs_destroy_cachep(); |