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Date:   Sun, 20 Mar 2022 19:55:57 +0900
From:   Byungchul Park <byungchul.park@lge.com>
To:     Theodore Ts'o <tytso@mit.edu>
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Subject: Re: [PATCH RFC v5 00/21] DEPT(Dependency Tracker)
Message-ID: <20220320105557.GA11318@X58A-UD3R>
References: <1647397593-16747-1-git-send-email-byungchul.park@lge.com>
 <YjKtZxjIKDJqsSrP@mit.edu>
 <20220318074945.GA17484@X58A-UD3R>
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On Fri, Mar 18, 2022 at 04:49:45PM +0900, Byungchul Park wrote:
> On Wed, Mar 16, 2022 at 11:39:19PM -0400, Theodore Ts'o wrote:
> > On Wed, Mar 16, 2022 at 11:26:12AM +0900, Byungchul Park wrote:
> > > I'm gonna re-add RFC for a while at Ted's request. But hard testing is
> > > needed to find false alarms for now that there's no false alarm with my
> > > system. I'm gonna look for other systems that might produce false
> > > alarms. And it'd be appreciated if you share it when you see any alarms
> > > with yours.
> > 
> > Is dept1.18_on_v5.17-rc7 roughly equivalent to the v5 version sent to
> 
> Yes.
> 
> > the list.  The commit date is March 16th, so I assume it was.  I tried
> > merging it with the ext4 dev branch, and tried enabling CONFIG_DEPT
> > and running xfstests.  The result was nearly test failing, because a 
> > DEPT warning.
> > 
> > I assume that this is due to some misconfiguration of DEPT on my part?
> 
> I guess it was becasue of the commit b1fca27d384e8("kernel debug:
> support resetting WARN*_ONCE"). Your script seems to reset WARN*_ONCE
> repeatedly.
> 
> But, yeah. It's *too much* that Dept warns it on the lack of pools. I
> will switch it to just pr_warn_once().
> 
> Plus, I will implement a new functionality to expand pools to prevent
> facing the situation in advance.
> 
> > And I'm curious why DEPT_WARN_ONCE is apparently getting many, many
> > times?
> > 
> > [  760.990409] DEPT_WARN_ONCE: Pool(ecxt) is empty.
> > [  770.319656] DEPT_WARN_ONCE: Pool(ecxt) is empty.
> > [  772.460360] DEPT_WARN_ONCE: Pool(ecxt) is empty.
> > [  784.039676] DEPT_WARN_ONCE: Pool(ecxt) is empty.
> > 
> > (and this goes on over and over...)
> > 
> > Here's the full output of the DEPT warning from trying to run
> > generic/001.  There is a similar warning for generic/002, generic/003,
> > etc., for a total of 468 failures out of 495 tests run.
> 
> Sorry for the noise. I will prevent this as described above.
> 
> > [  760.945068] run fstests generic/001 at 2022-03-16 08:16:53
> > [  760.985440] ------------[ cut here ]------------
> > [  760.990409] DEPT_WARN_ONCE: Pool(ecxt) is empty.
> > [  760.995166] WARNING: CPU: 1 PID: 73369 at kernel/dependency/dept.c:297 from_pool+0xc2/0x110
> > [  761.003915] CPU: 1 PID: 73369 Comm: bash Tainted: G        W         5.17.0-rc7-xfstests-00649-g5456f2312272 #520
> > [  761.014389] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > [  761.024363] RIP: 0010:from_pool+0xc2/0x110
> > [  761.028598] Code: 3d 32 62 96 01 00 75 c2 48 6b db 38 48 c7 c7 00 94 f1 ad 48 89 04 24 c6 05 1a 62 96 01 01 48 8b b3 20 9a 2f ae e8 2f dd bf 00 <0f> 0b 48 8b 04 24 eb 98 48 63 c2 48 0f af 86 28 9a 2f ae 48 03 86
> > [  761.048189] RSP: 0018:ffffa7ce4425fd48 EFLAGS: 00010086
> > [  761.053617] RAX: 0000000000000000 RBX: 00000000000000a8 RCX: 0000000000000000
> > [  761.060965] RDX: 0000000000000001 RSI: ffffffffadfb95e0 RDI: 00000000ffffffff
> > [  761.068322] RBP: 00000000001dc598 R08: 0000000000000000 R09: ffffa7ce4425fb90
> > [  761.075789] R10: fffffffffffe0aa0 R11: fffffffffffe0ae8 R12: ffff9768e07f0600
> > [  761.083063] R13: 0000000000000000 R14: 0000000000000246 R15: 0000000000000000
> > [  761.090312] FS:  00007fd4ecc4c740(0000) GS:ffff976999400000(0000) knlGS:0000000000000000
> > [  761.098623] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [  761.104580] CR2: 0000563c61657eb0 CR3: 00000001328fa001 CR4: 00000000003706e0
> > [  761.111921] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [  761.119171] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > [  761.126617] Call Trace:
> > [  761.129175]  <TASK>
> > [  761.131385]  add_ecxt+0x54/0x1c0
> > [  761.134736]  ? simple_attr_write+0x87/0x100
> > [  761.139063]  dept_event+0xaa/0x1d0
> > [  761.142687]  ? simple_attr_write+0x87/0x100
> > [  761.147089]  __mutex_unlock_slowpath+0x60/0x2d0
> > [  761.151866]  simple_attr_write+0x87/0x100
> > [  761.155997]  debugfs_attr_write+0x40/0x60
> > [  761.160124]  vfs_write+0xec/0x390
> > [  761.163557]  ksys_write+0x68/0xe0
> > [  761.167004]  do_syscall_64+0x43/0x90
> > [  761.170782]  entry_SYSCALL_64_after_hwframe+0x44/0xae
> > [  761.176204] RIP: 0033:0x7fd4ecd3df33
> > [  761.180010] Code: 8b 15 61 ef 0c 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 48 89 54 24 18
> > [  761.199551] RSP: 002b:00007ffe772d4808 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> > [  761.207240] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fd4ecd3df33
> > [  761.214583] RDX: 0000000000000002 RSI: 0000563c61657eb0 RDI: 0000000000000001
> > [  761.221835] RBP: 0000563c61657eb0 R08: 000000000000000a R09: 0000000000000001
> > [  761.229537] R10: 0000563c61902240 R11: 0000000000000246 R12: 0000000000000002
> > [  761.237239] R13: 00007fd4ece0e6a0 R14: 0000000000000002 R15: 00007fd4ece0e8a0
> > [  761.245283]  </TASK>
> > [  761.247586] ---[ end trace 0000000000000000 ]---
> > [  761.761829] EXT4-fs (dm-0): mounted filesystem with ordered data mode. Quota mode: none.
> > [  769.903489] EXT4-fs (dm-0): mounted filesystem with ordered data mode. Quota mode: none.
> > 
> > Let me know what I should do in order to fix this DEPT_WARN_ONCE?
> 
> I will let you know on all works done.

I have yet to decide the design for expanding pool on demand. I should
be careful in it because Dept is working in a very low layer. I will
have it done later.

However, I temporarily sized up the pools for heavy loaded system.
Besides that, all works have been done. I've just updated the same
branch.

https://github.com/lgebyungchulpark/linux-dept/commits/dept1.18_on_v5.17-rc7

This is just for your information.

Thanks,
Byungchul