Hi Filipe, any luck with this patch?:) Alex. On Wed, Oct 23, 2013 at 5:26 PM, Filipe David Manana <fdmanana@xxxxxxxxx> wrote: > On Wed, Oct 23, 2013 at 3:14 PM, Alex Lyakas > <alex.btrfs@xxxxxxxxxxxxxxxxx> wrote: >> Hello, >> >> On Wed, Oct 23, 2013 at 4:35 PM, Filipe David Manana <fdmanana@xxxxxxxxx> wrote: >>> On Wed, Oct 23, 2013 at 2:33 PM, Alex Lyakas >>> <alex.btrfs@xxxxxxxxxxxxxxxxx> wrote: >>>> Hi Filipe, >>>> >>>> >>>> On Tue, Aug 20, 2013 at 2:52 AM, Filipe David Borba Manana >>>> <fdmanana@xxxxxxxxx> wrote: >>>>> >>>>> This issue is simple to reproduce and observe if kmemleak is enabled. >>>>> Two simple ways to reproduce it: >>>>> >>>>> ** 1 >>>>> >>>>> $ mkfs.btrfs -f /dev/loop0 >>>>> $ mount /dev/loop0 /mnt/btrfs >>>>> $ btrfs balance start /mnt/btrfs >>>>> $ umount /mnt/btrfs >> >> So here it seems that the leak can only happen in case the block-group >> has a free-space inode. This is what the orphan item is added for. >> Yes, here kmemleak reports. >> But: if space_cache option is disabled (and nospace_cache) enabled, it >> seems that btrfs still creates the FREE_SPACE inodes, although they >> are empty because in cache_save_setup: >> >> inode = lookup_free_space_inode(root, block_group, path); >> if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) { >> ret = PTR_ERR(inode); >> btrfs_release_path(path); >> goto out; >> } >> >> if (IS_ERR(inode)) { >> ... >> ret = create_free_space_inode(root, trans, block_group, path); >> >> and only later it actually sets BTRFS_DC_WRITTEN if space_cache option >> is disabled. Amazing! >> Although this is a different issue, do you know perhaps why these >> empty inodes are needed? > > Don't know if they are needed. But you have a point, it seems odd to > create the free space cache inode if mount option nospace_cache was > supplied. Thanks Alex. Testing the following patch: > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index c43ee8a..eb1b7da 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -3162,6 +3162,9 @@ static int cache_save_setup(struct > btrfs_block_group_cache *block_group, > int retries = 0; > int ret = 0; > > + if (!btrfs_test_opt(root, SPACE_CACHE)) > + return 0; > + > /* > * If this block group is smaller than 100 megs don't bother caching the > * block group. > > >> >> Thanks! >> Alex. >> >> >> >>>>> >>>>> ** 2 >>>>> >>>>> $ mkfs.btrfs -f /dev/loop0 >>>>> $ mount /dev/loop0 /mnt/btrfs >>>>> $ touch /mnt/btrfs/foobar >>>>> $ rm -f /mnt/btrfs/foobar >>>>> $ umount /mnt/btrfs >>>> >>>> >>>> I tried the second repro script on kernel 3.8.13, and kmemleak does >>>> not report a leak (even if I force the kmemleak scan). I did not try >>>> the balance-repro script, though. Am I missing something? >>> >>> Maybe it's not an issue on 3.8.13 and older releases. >>> This was on btrfs-next from August 19. >>> >>> thanks for testing >>> >>>> >>>> Thanks, >>>> Alex. >>>> >>>> >>>>> >>>>> >>>>> After a while, kmemleak reports the leak: >>>>> >>>>> $ cat /sys/kernel/debug/kmemleak >>>>> unreferenced object 0xffff880402b13e00 (size 128): >>>>> comm "btrfs", pid 19621, jiffies 4341648183 (age 70057.844s) >>>>> hex dump (first 32 bytes): >>>>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >>>>> 00 fc c6 b1 04 88 ff ff 04 00 04 00 ad 4e ad de .............N.. >>>>> backtrace: >>>>> [<ffffffff817275a6>] kmemleak_alloc+0x26/0x50 >>>>> [<ffffffff8117832b>] kmem_cache_alloc_trace+0xeb/0x1d0 >>>>> [<ffffffffa04db499>] btrfs_alloc_block_rsv+0x39/0x70 [btrfs] >>>>> [<ffffffffa04f8bad>] btrfs_orphan_add+0x13d/0x1b0 [btrfs] >>>>> [<ffffffffa04e2b13>] btrfs_remove_block_group+0x143/0x500 [btrfs] >>>>> [<ffffffffa0518158>] btrfs_relocate_chunk.isra.63+0x618/0x790 [btrfs] >>>>> [<ffffffffa051bc27>] btrfs_balance+0x8f7/0xe90 [btrfs] >>>>> [<ffffffffa05240a0>] btrfs_ioctl_balance+0x250/0x550 [btrfs] >>>>> [<ffffffffa05269ca>] btrfs_ioctl+0xdfa/0x25f0 [btrfs] >>>>> [<ffffffff8119c936>] do_vfs_ioctl+0x96/0x570 >>>>> [<ffffffff8119cea1>] SyS_ioctl+0x91/0xb0 >>>>> [<ffffffff81750242>] system_call_fastpath+0x16/0x1b >>>>> [<ffffffffffffffff>] 0xffffffffffffffff >>>>> >>>>> This affects btrfs-next, revision be8e3cd00d7293dd177e3f8a4a1645ce09ca3acb >>>>> (Btrfs: separate out tests into their own directory). >>>>> >>>>> Signed-off-by: Filipe David Borba Manana <fdmanana@xxxxxxxxx> >>>>> --- >>>>> >>>>> V2: removed atomic_t member in struct btrfs_block_rsv, as suggested by >>>>> Josef Bacik, and use instead the condition reserved == 0 to decide >>>>> when to free the block. >>>>> V3: simplified patch, just kfree() (and not btrfs_free_block_rsv) the >>>>> root's orphan_block_rsv when free'ing the root. Thanks Josef for >>>>> the suggestion. >>>>> V4: use btrfs_free_block_rsv() instead of kfree(). The error I was getting >>>>> in xfstests when using btrfs_free_block_rsv() was unrelated, Josef just >>>>> pointed it to me (separate issue). >>>>> V5: move the free call below the iput() call, so that btrfs_evict_node() >>>>> can process the orphan_block_rsv first to do some needed cleanup before >>>>> we free it. >>>>> V6: free the root's orphan_block_rsv in close_ctree() too. After a balance >>>>> the orphan_block_rsv of the tree of tree roots was being leaked, because >>>>> free_fs_root() is only called for filesystem trees. >>>>> >>>>> fs/btrfs/disk-io.c | 5 +++++ >>>>> 1 file changed, 5 insertions(+) >>>>> >>>>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c >>>>> index 3b12c26..5d17163 100644 >>>>> --- a/fs/btrfs/disk-io.c >>>>> +++ b/fs/btrfs/disk-io.c >>>>> @@ -3430,6 +3430,8 @@ static void free_fs_root(struct btrfs_root *root) >>>>> { >>>>> iput(root->cache_inode); >>>>> WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree)); >>>>> + btrfs_free_block_rsv(root, root->orphan_block_rsv); >>>>> + root->orphan_block_rsv = NULL; >>>>> if (root->anon_dev) >>>>> free_anon_bdev(root->anon_dev); >>>>> free_extent_buffer(root->node); >>>>> @@ -3582,6 +3584,9 @@ int close_ctree(struct btrfs_root *root) >>>>> >>>>> btrfs_free_stripe_hash_table(fs_info); >>>>> >>>>> + btrfs_free_block_rsv(root, root->orphan_block_rsv); >>>>> + root->orphan_block_rsv = NULL; >>>>> + >>>>> return 0; >>>>> } >>>>> >>>>> -- >>>>> 1.7.9.5 >>>>> >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> >>> >>> -- >>> Filipe David Manana, >>> >>> "Reasonable men adapt themselves to the world. >>> Unreasonable men adapt the world to themselves. >>> That's why all progress depends on unreasonable men." > > > > -- > Filipe David Manana, > > "Reasonable men adapt themselves to the world. > Unreasonable men adapt the world to themselves. > That's why all progress depends on unreasonable men." -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html