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Message-ID: <20100105004741.GD3252@quack.suse.cz>
Date: Tue, 5 Jan 2010 01:47:42 +0100
From: Jan Kara <jack@...e.cz>
To: Greg Kroah-Hartman <gregkh@...e.de>, Theodore Ts'o <tytso@....edu>
Cc: linux-kernel@...r.kernel.org, stable@...nel.org,
stable-review@...nel.org, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
Dmitry Monakhov <dmonakhov@...nvz.org>, Jan Kara <jack@...e.cz>
Subject: Re: [PATCH 83/97] ext4: Fix potential quota deadlock
On Mon 04-01-10 16:33:36, Greg Kroah-Hartman wrote:
> From: Dmitry Monakhov <dmonakhov@...nvz.org>
>
> commit d21cd8f163ac44b15c465aab7306db931c606908 upstream.
Ted has found a serious bug in this patch over Christmas and fixed it.
Ted, do you prefer to just discard this patch or will you add your fixes?
Honza
> We have to delay vfs_dq_claim_space() until allocation context destruction.
> Currently we have following call-trace:
> ext4_mb_new_blocks()
> /* task is already holding ac->alloc_semp */
> ->ext4_mb_mark_diskspace_used
> ->vfs_dq_claim_space() /* acquire dqptr_sem here. Possible deadlock */
> ->ext4_mb_release_context() /* drop ac->alloc_semp here */
>
> Let's move quota claiming to ext4_da_update_reserve_space()
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.32-rc7 #18
> -------------------------------------------------------
> write-truncate-/3465 is trying to acquire lock:
> (&s->s_dquot.dqptr_sem){++++..}, at: [<c025e73b>] dquot_claim_space+0x3b/0x1b0
>
> but task is already holding lock:
> (&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #3 (&meta_group_info[i]->alloc_sem){++++..}:
> [<c017d04b>] __lock_acquire+0xd7b/0x1260
> [<c017d5ea>] lock_acquire+0xba/0xd0
> [<c0527191>] down_read+0x51/0x90
> [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
> [<c02d0c1c>] ext4_mb_free_blocks+0x46c/0x870
> [<c029c9d3>] ext4_free_blocks+0x73/0x130
> [<c02c8cfc>] ext4_ext_truncate+0x76c/0x8d0
> [<c02a8087>] ext4_truncate+0x187/0x5e0
> [<c01e0f7b>] vmtruncate+0x6b/0x70
> [<c022ec02>] inode_setattr+0x62/0x190
> [<c02a2d7a>] ext4_setattr+0x25a/0x370
> [<c022ee81>] notify_change+0x151/0x340
> [<c021349d>] do_truncate+0x6d/0xa0
> [<c0221034>] may_open+0x1d4/0x200
> [<c022412b>] do_filp_open+0x1eb/0x910
> [<c021244d>] do_sys_open+0x6d/0x140
> [<c021258e>] sys_open+0x2e/0x40
> [<c0103100>] sysenter_do_call+0x12/0x32
>
> -> #2 (&ei->i_data_sem){++++..}:
> [<c017d04b>] __lock_acquire+0xd7b/0x1260
> [<c017d5ea>] lock_acquire+0xba/0xd0
> [<c0527191>] down_read+0x51/0x90
> [<c02a5787>] ext4_get_blocks+0x47/0x450
> [<c02a74c1>] ext4_getblk+0x61/0x1d0
> [<c02a7a7f>] ext4_bread+0x1f/0xa0
> [<c02bcddc>] ext4_quota_write+0x12c/0x310
> [<c0262d23>] qtree_write_dquot+0x93/0x120
> [<c0261708>] v2_write_dquot+0x28/0x30
> [<c025d3fb>] dquot_commit+0xab/0xf0
> [<c02be977>] ext4_write_dquot+0x77/0x90
> [<c02be9bf>] ext4_mark_dquot_dirty+0x2f/0x50
> [<c025e321>] dquot_alloc_inode+0x101/0x180
> [<c029fec2>] ext4_new_inode+0x602/0xf00
> [<c02ad789>] ext4_create+0x89/0x150
> [<c0221ff2>] vfs_create+0xa2/0xc0
> [<c02246e7>] do_filp_open+0x7a7/0x910
> [<c021244d>] do_sys_open+0x6d/0x140
> [<c021258e>] sys_open+0x2e/0x40
> [<c0103100>] sysenter_do_call+0x12/0x32
>
> -> #1 (&sb->s_type->i_mutex_key#7/4){+.+...}:
> [<c017d04b>] __lock_acquire+0xd7b/0x1260
> [<c017d5ea>] lock_acquire+0xba/0xd0
> [<c0526505>] mutex_lock_nested+0x65/0x2d0
> [<c0260c9d>] vfs_load_quota_inode+0x4bd/0x5a0
> [<c02610af>] vfs_quota_on_path+0x5f/0x70
> [<c02bc812>] ext4_quota_on+0x112/0x190
> [<c026345a>] sys_quotactl+0x44a/0x8a0
> [<c0103100>] sysenter_do_call+0x12/0x32
>
> -> #0 (&s->s_dquot.dqptr_sem){++++..}:
> [<c017d361>] __lock_acquire+0x1091/0x1260
> [<c017d5ea>] lock_acquire+0xba/0xd0
> [<c0527191>] down_read+0x51/0x90
> [<c025e73b>] dquot_claim_space+0x3b/0x1b0
> [<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
> [<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
> [<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
> [<c02a5966>] ext4_get_blocks+0x226/0x450
> [<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
> [<c02a6ed6>] ext4_da_writepages+0x506/0x790
> [<c01de272>] do_writepages+0x22/0x50
> [<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
> [<c01d7b9b>] filemap_flush+0x2b/0x30
> [<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
> [<c029e595>] ext4_release_file+0x75/0xb0
> [<c0216b59>] __fput+0xf9/0x210
> [<c0216c97>] fput+0x27/0x30
> [<c02122dc>] filp_close+0x4c/0x80
> [<c014510e>] put_files_struct+0x6e/0xd0
> [<c01451b7>] exit_files+0x47/0x60
> [<c0146a24>] do_exit+0x144/0x710
> [<c0147028>] do_group_exit+0x38/0xa0
> [<c0159abc>] get_signal_to_deliver+0x2ac/0x410
> [<c0102849>] do_notify_resume+0xb9/0x890
> [<c01032d2>] work_notifysig+0x13/0x21
>
> other info that might help us debug this:
>
> 3 locks held by write-truncate-/3465:
> #0: (jbd2_handle){+.+...}, at: [<c02e1f8f>] start_this_handle+0x38f/0x5c0
> #1: (&ei->i_data_sem){++++..}, at: [<c02a57f6>] ext4_get_blocks+0xb6/0x450
> #2: (&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
>
> stack backtrace:
> Pid: 3465, comm: write-truncate- Not tainted 2.6.32-rc7 #18
> Call Trace:
> [<c0524cb3>] ? printk+0x1d/0x22
> [<c017ac9a>] print_circular_bug+0xca/0xd0
> [<c017d361>] __lock_acquire+0x1091/0x1260
> [<c016bca2>] ? sched_clock_local+0xd2/0x170
> [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
> [<c017d5ea>] lock_acquire+0xba/0xd0
> [<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
> [<c0527191>] down_read+0x51/0x90
> [<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
> [<c025e73b>] dquot_claim_space+0x3b/0x1b0
> [<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
> [<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
> [<c02c601d>] ? ext4_ext_find_extent+0x25d/0x280
> [<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
> [<c016bca2>] ? sched_clock_local+0xd2/0x170
> [<c016be60>] ? sched_clock_cpu+0x120/0x160
> [<c016beef>] ? cpu_clock+0x4f/0x60
> [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
> [<c052712c>] ? down_write+0x8c/0xa0
> [<c02a5966>] ext4_get_blocks+0x226/0x450
> [<c016be60>] ? sched_clock_cpu+0x120/0x160
> [<c016beef>] ? cpu_clock+0x4f/0x60
> [<c017908b>] ? trace_hardirqs_off+0xb/0x10
> [<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
> [<c01d69cc>] ? find_get_pages_tag+0x16c/0x180
> [<c01d6860>] ? find_get_pages_tag+0x0/0x180
> [<c02a73bd>] ? __mpage_da_writepage+0x16d/0x1a0
> [<c01dfc4e>] ? pagevec_lookup_tag+0x2e/0x40
> [<c01ddf1b>] ? write_cache_pages+0xdb/0x3d0
> [<c02a7250>] ? __mpage_da_writepage+0x0/0x1a0
> [<c02a6ed6>] ext4_da_writepages+0x506/0x790
> [<c016beef>] ? cpu_clock+0x4f/0x60
> [<c016bca2>] ? sched_clock_local+0xd2/0x170
> [<c016be60>] ? sched_clock_cpu+0x120/0x160
> [<c016be60>] ? sched_clock_cpu+0x120/0x160
> [<c02a69d0>] ? ext4_da_writepages+0x0/0x790
> [<c01de272>] do_writepages+0x22/0x50
> [<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
> [<c01d7b9b>] filemap_flush+0x2b/0x30
> [<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
> [<c029e595>] ext4_release_file+0x75/0xb0
> [<c0216b59>] __fput+0xf9/0x210
> [<c0216c97>] fput+0x27/0x30
> [<c02122dc>] filp_close+0x4c/0x80
> [<c014510e>] put_files_struct+0x6e/0xd0
> [<c01451b7>] exit_files+0x47/0x60
> [<c0146a24>] do_exit+0x144/0x710
> [<c017b163>] ? lock_release_holdtime+0x33/0x210
> [<c0528137>] ? _spin_unlock_irq+0x27/0x30
> [<c0147028>] do_group_exit+0x38/0xa0
> [<c017babb>] ? trace_hardirqs_on+0xb/0x10
> [<c0159abc>] get_signal_to_deliver+0x2ac/0x410
> [<c0102849>] do_notify_resume+0xb9/0x890
> [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
> [<c017b163>] ? lock_release_holdtime+0x33/0x210
> [<c0165b50>] ? autoremove_wake_function+0x0/0x50
> [<c017ba54>] ? trace_hardirqs_on_caller+0x134/0x190
> [<c017babb>] ? trace_hardirqs_on+0xb/0x10
> [<c0300ba4>] ? security_file_permission+0x14/0x20
> [<c0215761>] ? vfs_write+0x131/0x190
> [<c0214f50>] ? do_sync_write+0x0/0x120
> [<c0103115>] ? sysenter_do_call+0x27/0x32
> [<c01032d2>] work_notifysig+0x13/0x21
>
> CC: Theodore Ts'o <tytso@....edu>
> Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
> Signed-off-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> ---
> fs/ext4/inode.c | 9 +++++++--
> fs/ext4/mballoc.c | 6 ------
> 2 files changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 374d38c..9fc624d 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1088,7 +1088,7 @@ static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
> static void ext4_da_update_reserve_space(struct inode *inode, int used)
> {
> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> - int total, mdb, mdb_free;
> + int total, mdb, mdb_free, mdb_claim = 0;
>
> spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
> /* recalculate the number of metablocks still need to be reserved */
> @@ -1101,7 +1101,9 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
>
> if (mdb_free) {
> /* Account for allocated meta_blocks */
> - mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
> + mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks;
> + BUG_ON(mdb_free < mdb_claim);
> + mdb_free -= mdb_claim;
>
> /* update fs dirty blocks counter */
> percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
> @@ -1112,8 +1114,11 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
> /* update per-inode reservations */
> BUG_ON(used > EXT4_I(inode)->i_reserved_data_blocks);
> EXT4_I(inode)->i_reserved_data_blocks -= used;
> + percpu_counter_sub(&sbi->s_dirtyblocks_counter, used + mdb_claim);
> spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
>
> + vfs_dq_claim_block(inode, used + mdb_claim);
> +
> /*
> * free those over-booking quota for metadata blocks
> */
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 7d71148..82b9778 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2755,12 +2755,6 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
> if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED))
> /* release all the reserved blocks if non delalloc */
> percpu_counter_sub(&sbi->s_dirtyblocks_counter, reserv_blks);
> - else {
> - percpu_counter_sub(&sbi->s_dirtyblocks_counter,
> - ac->ac_b_ex.fe_len);
> - /* convert reserved quota blocks to real quota blocks */
> - vfs_dq_claim_block(ac->ac_inode, ac->ac_b_ex.fe_len);
> - }
>
> if (sbi->s_log_groups_per_flex) {
> ext4_group_t flex_group = ext4_flex_group(sbi,
> --
> 1.6.6
>
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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