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Date:   Mon, 21 Feb 2022 20:02:04 +0100
From:   Jan Kara <jack@suse.cz>
To:     Byungchul Park <byungchul.park@lge.com>
Cc:     torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com,
        linux-ide@vger.kernel.org, adilger.kernel@dilger.ca,
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        hamohammed.sa@gmail.com
Subject: Re: Report 2 in ext4 and journal based on v5.17-rc1
Message-ID: <20220221190204.q675gtsb6qhylywa@quack3.lan>
References: <1645095472-26530-1-git-send-email-byungchul.park@lge.com>
 <1645096204-31670-1-git-send-email-byungchul.park@lge.com>
 <1645096204-31670-2-git-send-email-byungchul.park@lge.com>
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In-Reply-To: <1645096204-31670-2-git-send-email-byungchul.park@lge.com>
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So I was trying to understand what this report is about for some time but
honestly I have failed...

On Thu 17-02-22 20:10:04, Byungchul Park wrote:
> [    9.008161] ===================================================
> [    9.008163] DEPT: Circular dependency has been detected.
> [    9.008164] 5.17.0-rc1-00015-gb94f67143867-dirty #2 Tainted: G        W
> [    9.008166] ---------------------------------------------------
> [    9.008167] summary
> [    9.008167] ---------------------------------------------------
> [    9.008168] *** DEADLOCK ***
> [    9.008168]
> [    9.008168] context A
> [    9.008169]     [S] (unknown)(&(&journal->j_wait_transaction_locked)->dmap:0)
> [    9.008171]     [W] wait(&(&journal->j_wait_commit)->dmap:0)
> [    9.008172]     [E] event(&(&journal->j_wait_transaction_locked)->dmap:0)
> [    9.008173]
> [    9.008173] context B
> [    9.008174]     [S] down_write(mapping.invalidate_lock:0)
> [    9.008175]     [W] wait(&(&journal->j_wait_transaction_locked)->dmap:0)
> [    9.008176]     [E] up_write(mapping.invalidate_lock:0)
> [    9.008177]
> [    9.008178] context C
> [    9.008179]     [S] (unknown)(&(&journal->j_wait_commit)->dmap:0)
> [    9.008180]     [W] down_write(mapping.invalidate_lock:0)
> [    9.008181]     [E] event(&(&journal->j_wait_commit)->dmap:0)
> [    9.008181]
> [    9.008182] [S]: start of the event context
> [    9.008183] [W]: the wait blocked
> [    9.008183] [E]: the event not reachable

So what situation is your tool complaining about here? Can you perhaps show
it here in more common visualization like:

TASK1				TASK2
				does foo, grabs Z
does X, grabs lock Y
blocks on Z
				blocks on Y

or something like that? Because I was not able to decipher this from the
report even after trying for some time...

								Honza

				
> [    9.008184] ---------------------------------------------------
> [    9.008184] context A's detail
> [    9.008185] ---------------------------------------------------
> [    9.008186] context A
> [    9.008186]     [S] (unknown)(&(&journal->j_wait_transaction_locked)->dmap:0)
> [    9.008187]     [W] wait(&(&journal->j_wait_commit)->dmap:0)
> [    9.008188]     [E] event(&(&journal->j_wait_transaction_locked)->dmap:0)
> [    9.008189]
> [    9.008190] [S] (unknown)(&(&journal->j_wait_transaction_locked)->dmap:0):
> [    9.008191] (N/A)
> [    9.008191]
> [    9.008192] [W] wait(&(&journal->j_wait_commit)->dmap:0):
> [    9.008193] prepare_to_wait (kernel/sched/wait.c:275) 
> [    9.008197] stacktrace:
> [    9.008198] __schedule (kernel/sched/sched.h:1318 kernel/sched/sched.h:1616 kernel/sched/core.c:6213) 
> [    9.008200] schedule (kernel/sched/core.c:6373 (discriminator 1)) 
> [    9.008201] kjournald2 (fs/jbd2/journal.c:250) 
> [    9.008203] kthread (kernel/kthread.c:377) 
> [    9.008206] ret_from_fork (arch/x86/entry/entry_64.S:301) 
> [    9.008209]
> [    9.008209] [E] event(&(&journal->j_wait_transaction_locked)->dmap:0):
> [    9.008210] __wake_up_common (kernel/sched/wait.c:108) 
> [    9.008212] stacktrace:
> [    9.008213] dept_event (kernel/dependency/dept.c:2337) 
> [    9.008215] __wake_up_common (kernel/sched/wait.c:109) 
> [    9.008217] __wake_up_common_lock (./include/linux/spinlock.h:428 (discriminator 1) kernel/sched/wait.c:141 (discriminator 1)) 
> [    9.008218] jbd2_journal_commit_transaction (fs/jbd2/commit.c:583) 
> [    9.008221] kjournald2 (fs/jbd2/journal.c:214 (discriminator 3)) 
> [    9.008223] kthread (kernel/kthread.c:377) 
> [    9.008224] ret_from_fork (arch/x86/entry/entry_64.S:301) 
> [    9.008226] ---------------------------------------------------
> [    9.008226] context B's detail
> [    9.008227] ---------------------------------------------------
> [    9.008228] context B
> [    9.008228]     [S] down_write(mapping.invalidate_lock:0)
> [    9.008229]     [W] wait(&(&journal->j_wait_transaction_locked)->dmap:0)
> [    9.008230]     [E] up_write(mapping.invalidate_lock:0)
> [    9.008231]
> [    9.008232] [S] down_write(mapping.invalidate_lock:0):
> [    9.008233] ext4_da_write_begin (fs/ext4/truncate.h:21 fs/ext4/inode.c:2963) 
> [    9.008237] stacktrace:
> [    9.008237] down_write (kernel/locking/rwsem.c:1514) 
> [    9.008239] ext4_da_write_begin (fs/ext4/truncate.h:21 fs/ext4/inode.c:2963) 
> [    9.008241] generic_perform_write (mm/filemap.c:3784) 
> [    9.008243] ext4_buffered_write_iter (fs/ext4/file.c:269) 
> [    9.008245] ext4_file_write_iter (fs/ext4/file.c:677) 
> [    9.008247] new_sync_write (fs/read_write.c:504 (discriminator 1)) 
> [    9.008250] vfs_write (fs/read_write.c:590) 
> [    9.008251] ksys_write (fs/read_write.c:644) 
> [    9.008253] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) 
> [    9.008255] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113) 
> [    9.008258]
> [    9.008258] [W] wait(&(&journal->j_wait_transaction_locked)->dmap:0):
> [    9.008259] prepare_to_wait (kernel/sched/wait.c:275) 
> [    9.008261] stacktrace:
> [    9.008261] __schedule (kernel/sched/sched.h:1318 kernel/sched/sched.h:1616 kernel/sched/core.c:6213) 
> [    9.008263] schedule (kernel/sched/core.c:6373 (discriminator 1)) 
> [    9.008264] wait_transaction_locked (fs/jbd2/transaction.c:184) 
> [    9.008266] add_transaction_credits (fs/jbd2/transaction.c:248 (discriminator 3)) 
> [    9.008267] start_this_handle (fs/jbd2/transaction.c:427) 
> [    9.008269] jbd2__journal_start (fs/jbd2/transaction.c:526) 
> [    9.008271] __ext4_journal_start_sb (fs/ext4/ext4_jbd2.c:105) 
> [    9.008273] ext4_truncate (fs/ext4/inode.c:4164) 
> [    9.008274] ext4_da_write_begin (./include/linux/fs.h:827 fs/ext4/truncate.h:23 fs/ext4/inode.c:2963) 
> [    9.008276] generic_perform_write (mm/filemap.c:3784) 
> [    9.008277] ext4_buffered_write_iter (fs/ext4/file.c:269) 
> [    9.008279] ext4_file_write_iter (fs/ext4/file.c:677) 
> [    9.008281] new_sync_write (fs/read_write.c:504 (discriminator 1)) 
> [    9.008283] vfs_write (fs/read_write.c:590) 
> [    9.008284] ksys_write (fs/read_write.c:644) 
> [    9.008285] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) 
> [    9.008287]
> [    9.008288] [E] up_write(mapping.invalidate_lock:0):
> [    9.008288] ext4_da_get_block_prep (fs/ext4/inode.c:1795 fs/ext4/inode.c:1829) 
> [    9.008291] ---------------------------------------------------
> [    9.008291] context C's detail
> [    9.008292] ---------------------------------------------------
> [    9.008292] context C
> [    9.008293]     [S] (unknown)(&(&journal->j_wait_commit)->dmap:0)
> [    9.008294]     [W] down_write(mapping.invalidate_lock:0)
> [    9.008295]     [E] event(&(&journal->j_wait_commit)->dmap:0)
> [    9.008296]
> [    9.008297] [S] (unknown)(&(&journal->j_wait_commit)->dmap:0):
> [    9.008298] (N/A)
> [    9.008298]
> [    9.008299] [W] down_write(mapping.invalidate_lock:0):
> [    9.008299] ext4_da_write_begin (fs/ext4/truncate.h:21 fs/ext4/inode.c:2963) 
> [    9.008302] stacktrace:
> [    9.008302] down_write (kernel/locking/rwsem.c:1514) 
> [    9.008304] ext4_da_write_begin (fs/ext4/truncate.h:21 fs/ext4/inode.c:2963) 
> [    9.008305] generic_perform_write (mm/filemap.c:3784) 
> [    9.008307] ext4_buffered_write_iter (fs/ext4/file.c:269) 
> [    9.008309] ext4_file_write_iter (fs/ext4/file.c:677) 
> [    9.008311] new_sync_write (fs/read_write.c:504 (discriminator 1)) 
> [    9.008312] vfs_write (fs/read_write.c:590) 
> [    9.008314] ksys_write (fs/read_write.c:644) 
> [    9.008315] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) 
> [    9.008316] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113) 
> [    9.008318]
> [    9.008319] [E] event(&(&journal->j_wait_commit)->dmap:0):
> [    9.008320] __wake_up_common (kernel/sched/wait.c:108) 
> [    9.008321] stacktrace:
> [    9.008322] __wake_up_common (kernel/sched/wait.c:109) 
> [    9.008323] __wake_up_common_lock (./include/linux/spinlock.h:428 (discriminator 1) kernel/sched/wait.c:141 (discriminator 1)) 
> [    9.008324] __jbd2_log_start_commit (fs/jbd2/journal.c:508) 
> [    9.008326] jbd2_log_start_commit (fs/jbd2/journal.c:527) 
> [    9.008327] __jbd2_journal_force_commit (fs/jbd2/journal.c:560) 
> [    9.008329] jbd2_journal_force_commit_nested (fs/jbd2/journal.c:583) 
> [    9.008331] ext4_should_retry_alloc (fs/ext4/balloc.c:670 (discriminator 3)) 
> [    9.008332] ext4_da_write_begin (fs/ext4/inode.c:2965 (discriminator 1)) 
> [    9.008334] generic_perform_write (mm/filemap.c:3784) 
> [    9.008335] ext4_buffered_write_iter (fs/ext4/file.c:269) 
> [    9.008337] ext4_file_write_iter (fs/ext4/file.c:677) 
> [    9.008339] new_sync_write (fs/read_write.c:504 (discriminator 1)) 
> [    9.008341] vfs_write (fs/read_write.c:590) 
> [    9.008342] ksys_write (fs/read_write.c:644) 
> [    9.008343] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) 
> [    9.008345] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113) 
> [    9.008347] ---------------------------------------------------
> [    9.008348] information that might be helpful
> [    9.008348] ---------------------------------------------------
> [    9.008349] CPU: 0 PID: 89 Comm: jbd2/sda1-8 Tainted: G        W         5.17.0-rc1-00015-gb94f67143867-dirty #2
> [    9.008352] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> [    9.008353] Call Trace:
> [    9.008354]  <TASK>
> [    9.008355] dump_stack_lvl (lib/dump_stack.c:107) 
> [    9.008358] print_circle (./arch/x86/include/asm/atomic.h:108 ./include/linux/atomic/atomic-instrumented.h:258 kernel/dependency/dept.c:157 kernel/dependency/dept.c:762) 
> [    9.008360] ? print_circle (kernel/dependency/dept.c:1086) 
> [    9.008362] cb_check_dl (kernel/dependency/dept.c:1104) 
> [    9.008364] bfs (kernel/dependency/dept.c:860) 
> [    9.008366] add_dep (kernel/dependency/dept.c:1423) 
> [    9.008368] do_event.isra.25 (kernel/dependency/dept.c:1651) 
> [    9.008370] ? __wake_up_common (kernel/sched/wait.c:108) 
> [    9.008372] dept_event (kernel/dependency/dept.c:2337) 
> [    9.008374] __wake_up_common (kernel/sched/wait.c:109) 
> [    9.008376] __wake_up_common_lock (./include/linux/spinlock.h:428 (discriminator 1) kernel/sched/wait.c:141 (discriminator 1)) 
> [    9.008379] jbd2_journal_commit_transaction (fs/jbd2/commit.c:583) 
> [    9.008381] ? arch_stack_walk (arch/x86/kernel/stacktrace.c:24) 
> [    9.008385] ? ret_from_fork (arch/x86/entry/entry_64.S:301) 
> [    9.008387] ? dept_enable_hardirq (./arch/x86/include/asm/current.h:15 kernel/dependency/dept.c:241 kernel/dependency/dept.c:999 kernel/dependency/dept.c:1043 kernel/dependency/dept.c:1843) 
> [    9.008389] ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/irqflags.h:45 ./arch/x86/include/asm/irqflags.h:80 ./arch/x86/include/asm/irqflags.h:138 ./include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194) 
> [    9.008392] ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/preempt.h:103 ./include/linux/spinlock_api_smp.h:152 kernel/locking/spinlock.c:194) 
> [    9.008394] ? try_to_del_timer_sync (kernel/time/timer.c:1239) 
> [    9.008396] kjournald2 (fs/jbd2/journal.c:214 (discriminator 3)) 
> [    9.008398] ? prepare_to_wait_exclusive (kernel/sched/wait.c:431) 
> [    9.008400] ? commit_timeout (fs/jbd2/journal.c:173) 
> [    9.008402] kthread (kernel/kthread.c:377) 
> [    9.008404] ? kthread_complete_and_exit (kernel/kthread.c:332) 
> [    9.008407] ret_from_fork (arch/x86/entry/entry_64.S:301) 
> [    9.008410]  </TASK>
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR