From 5d3ee20855e28169d711b394857ee608a5023094 Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Wed, 3 Apr 2013 22:08:52 -0400 Subject: [PATCH] ext4: fix journal callback list traversal It is incorrect to use list_for_each_entry_safe() for journal callback traversial because ->next may be removed by other task: ->ext4_mb_free_metadata() ->ext4_mb_free_metadata() ->ext4_journal_callback_del() This results in the following issue: WARNING: at lib/list_debug.c:62 __list_del_entry+0x1c0/0x250() Hardware name: list_del corruption. prev->next should be ffff88019a4ec198, but was 6b6b6b6b6b6b6b6b Modules linked in: cpufreq_ondemand acpi_cpufreq freq_table mperf coretemp kvm_intel kvm crc32c_intel ghash_clmulni_intel microcode sg xhci_hcd button sd_mod crc_t10dif aesni_intel ablk_helper cryptd lrw aes_x86_64 xts gf128mul ahci libahci pata_acpi ata_generic dm_mirror dm_region_hash dm_log dm_mod Pid: 16400, comm: jbd2/dm-1-8 Tainted: G W 3.8.0-rc3+ #107 Call Trace: [] warn_slowpath_common+0xad/0xf0 [] warn_slowpath_fmt+0x46/0x50 [] ? ext4_journal_commit_callback+0x99/0xc0 [] __list_del_entry+0x1c0/0x250 [] ext4_journal_commit_callback+0x6f/0xc0 [] jbd2_journal_commit_transaction+0x23a6/0x2570 [] ? try_to_del_timer_sync+0x82/0xa0 [] ? del_timer_sync+0x91/0x1e0 [] kjournald2+0x19f/0x6a0 [] ? wake_up_bit+0x40/0x40 [] ? bit_spin_lock+0x80/0x80 [] kthread+0x10e/0x120 [] ? __init_kthread_worker+0x70/0x70 [] ret_from_fork+0x7c/0xb0 [] ? __init_kthread_worker+0x70/0x70 This patch fix the issue as follows: - ext4_journal_commit_callback() make list truly traversial safe simply by always starting from list_head - fix race between two ext4_journal_callback_del() and ext4_journal_callback_try_del() Signed-off-by: Dmitry Monakhov Signed-off-by: "Theodore Ts'o" Reviewed-by: Jan Kara Cc: stable@vger.kernel.com --- fs/ext4/ext4_jbd2.h | 6 +++++- fs/ext4/mballoc.c | 8 ++++---- fs/ext4/super.c | 7 +++++-- 3 files changed, 14 insertions(+), 7 deletions(-) diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h index 4c216b1bf20c..aeed0bac693b 100644 --- a/fs/ext4/ext4_jbd2.h +++ b/fs/ext4/ext4_jbd2.h @@ -194,16 +194,20 @@ static inline void ext4_journal_callback_add(handle_t *handle, * ext4_journal_callback_del: delete a registered callback * @handle: active journal transaction handle on which callback was registered * @jce: registered journal callback entry to unregister + * Return true if object was sucessfully removed */ -static inline void ext4_journal_callback_del(handle_t *handle, +static inline bool ext4_journal_callback_try_del(handle_t *handle, struct ext4_journal_cb_entry *jce) { + bool deleted; struct ext4_sb_info *sbi = EXT4_SB(handle->h_transaction->t_journal->j_private); spin_lock(&sbi->s_md_lock); + deleted = !list_empty(&jce->jce_list); list_del_init(&jce->jce_list); spin_unlock(&sbi->s_md_lock); + return deleted; } int diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 36c82a39d03f..580aada3d1bb 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4423,11 +4423,11 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b, node = rb_prev(new_node); if (node) { entry = rb_entry(node, struct ext4_free_data, efd_node); - if (can_merge(entry, new_entry)) { + if (can_merge(entry, new_entry) && + ext4_journal_callback_try_del(handle, &entry->efd_jce)) { new_entry->efd_start_cluster = entry->efd_start_cluster; new_entry->efd_count += entry->efd_count; rb_erase(node, &(db->bb_free_root)); - ext4_journal_callback_del(handle, &entry->efd_jce); kmem_cache_free(ext4_free_data_cachep, entry); } } @@ -4435,10 +4435,10 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b, node = rb_next(new_node); if (node) { entry = rb_entry(node, struct ext4_free_data, efd_node); - if (can_merge(new_entry, entry)) { + if (can_merge(new_entry, entry) && + ext4_journal_callback_try_del(handle, &entry->efd_jce)) { new_entry->efd_count += entry->efd_count; rb_erase(node, &(db->bb_free_root)); - ext4_journal_callback_del(handle, &entry->efd_jce); kmem_cache_free(ext4_free_data_cachep, entry); } } diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 5d6d53578124..67ae9e332d42 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -353,10 +353,13 @@ static void ext4_journal_commit_callback(journal_t *journal, transaction_t *txn) struct super_block *sb = journal->j_private; struct ext4_sb_info *sbi = EXT4_SB(sb); int error = is_journal_aborted(journal); - struct ext4_journal_cb_entry *jce, *tmp; + struct ext4_journal_cb_entry *jce; + BUG_ON(txn->t_state == T_FINISHED); spin_lock(&sbi->s_md_lock); - list_for_each_entry_safe(jce, tmp, &txn->t_private_list, jce_list) { + while (!list_empty(&txn->t_private_list)) { + jce = list_entry(txn->t_private_list.next, + struct ext4_journal_cb_entry, jce_list); list_del_init(&jce->jce_list); spin_unlock(&sbi->s_md_lock); jce->jce_func(sb, jce, error);