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Date:   Mon, 15 May 2023 14:02:50 +0300
From:   Ido Schimmel <idosch@idosch.org>
To:     Angus Chen <angus.chen@jaguarmicro.com>
Cc:     davem@davemloft.net, dsahern@kernel.org, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] net: Remove low_thresh in ip defrag
Message-ID: <ZGIRWjNcfqI8yY8W@shredder>
References: <20230512010152.1602-1-angus.chen@jaguarmicro.com>
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In-Reply-To: <20230512010152.1602-1-angus.chen@jaguarmicro.com>
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On Fri, May 12, 2023 at 09:01:52AM +0800, Angus Chen wrote:
> As low_thresh has no work in fragment reassembles,del it.
> And Mark it deprecated in sysctl Document.
> 
> Signed-off-by: Angus Chen <angus.chen@jaguarmicro.com>

Getting the following traces with this patch when creating a netns:

[   10.186564] ------------[ cut here ]------------                                                                                                                                                                                                                                                                    
[   10.186596] sysctl net/ipv4/ipfrag_low_thresh: data points to kernel global data: ipfrag_low_thresh_unused                                              
[   10.186648] WARNING: CPU: 1 PID: 193 at net/sysctl_net.c:155 register_net_sysctl+0xaf/0x150
[   10.186659] Modules linked in:                                                                                                                                                                                                                                                                                      
[   10.186667] CPU: 1 PID: 193 Comm: ip Not tainted 6.4.0-rc1-custom-gd1e4632b304c #57
[   10.186672] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc37 04/01/2014
[   10.186681] RIP: 0010:register_net_sysctl+0xaf/0x150                                                                                                    
[   10.186691] Code: 00 a3 72 b9 48 81 fd 00 00 20 a3 73 b0 48 c7 c1 0b 7b dc a1 48 8b 13 4c 8b 43 08 4c 89 ee 48 c7 c7 d0 c2 eb a1 e8 41 66 44 ff <0f> 0b 66 81 63 14 6d ff 48 8b 53 40 48 83 c3 40 48 85 d2 75 8b 5b
[   10.186696] RSP: 0018:ffffaca28031bd98 EFLAGS: 00010282                                                                                                 
[   10.186705] RAX: 0000000000000000 RBX: ffff9daa80846640 RCX: 00000000ffffdfff
[   10.186711] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
[   10.186714] RBP: ffffffffa3162b28 R08: 00000000ffffdfff R09: 00000000ffffdfff
[   10.186717] R10: ffffffffa2670880 R11: ffffffffa2670880 R12: ffff9daa83100000
[   10.186720] R13: ffffffffa1e19fc9 R14: ffff9daa80846600 R15: 0000000000000000                                 
[   10.186728] FS:  00007fe0e810d740(0000) GS:ffff9dabb7c80000(0000) knlGS:0000000000000000   
[   10.186732] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033                                                                                                                                                                                                                                                       
[   10.186735] CR2: 000056387c867530 CR3: 000000010318d005 CR4: 0000000000170ee0                       
[   10.186739] Call Trace:                                                                                                                                 
[   10.186766]  <TASK>                                                                                                                                     
[   10.186807]  ipv4_frags_init_net+0xe1/0x180                                                                                                                                                                                                                                                                         
[   10.186817]  ops_init+0x37/0x120                                                                                                                        
[   10.186826]  setup_net+0x12a/0x290                                                                                                                      
[   10.186831]  copy_net_ns+0xd8/0x180                                                                                                                     
[   10.186836]  create_new_namespaces+0x123/0x300                                                                                                          
[   10.186849]  unshare_nsproxy_namespaces+0x60/0xa0                                                                                                       
[   10.186857]  ksys_unshare+0x181/0x360                                                                                                                   
[   10.186869]  __x64_sys_unshare+0x12/0x20                                                                                                                
[   10.186876]  do_syscall_64+0x38/0x80                         
[   10.186885]  entry_SYSCALL_64_after_hwframe+0x63/0xcd                                                                                                   
[   10.186897] RIP: 0033:0x7fe0e82f23cb
[   10.186908] Code: 73 01 c3 48 8b 0d 65 5a 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 10 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 35 5a 0c 00 f7 d8 64 89 01 48
[   10.186912] RSP: 002b:00007ffe0513ec08 EFLAGS: 00000217 ORIG_RAX: 0000000000000110
[   10.186918] RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fe0e82f23cb
[   10.186921] RDX: 0000000000000000 RSI: 000056387c863113 RDI: 0000000040000000
[   10.186924] RBP: 000056387c862c3a R08: 0000000000000000 R09: 0000000000000073
[   10.186927] R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000000000
[   10.186930] R13: 00007fe0e810d6b8 R14: 00007ffe05140e10 R15: 000056387c864fe5
[   10.186934]  </TASK>
[   10.186936] ---[ end trace 0000000000000000 ]---
[   10.187912] ------------[ cut here ]------------
[   10.187917] sysctl net/ipv6/ip6frag_low_thresh: data points to kernel global data: ip6_frags_low_thresh_unused
[   10.187955] WARNING: CPU: 0 PID: 193 at net/sysctl_net.c:155 register_net_sysctl+0xaf/0x150
[   10.187966] Modules linked in:
[   10.187970] CPU: 0 PID: 193 Comm: ip Tainted: G        W          6.4.0-rc1-custom-gd1e4632b304c #57
[   10.187980] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc37 04/01/2014
[   10.187982] RIP: 0010:register_net_sysctl+0xaf/0x150
[   10.187989] Code: 00 a3 72 b9 48 81 fd 00 00 20 a3 73 b0 48 c7 c1 0b 7b dc a1 48 8b 13 4c 8b 43 08 4c 89 ee 48 c7 c7 d0 c2 eb a1 e8 41 66 44 ff <0f> 0b 66 81 63 14 6d ff 48 8b 53 40 48 83 c3 40 48 85 d2 75 8b 5b
[   10.187993] RSP: 0018:ffffaca28031bd98 EFLAGS: 00010282
[   10.187998] RAX: 0000000000000000 RBX: ffff9daa822d8240 RCX: 00000000ffffdfff
[   10.188002] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
[   10.188004] RBP: ffffffffa28ade80 R08: 00000000ffffdfff R09: 00000000ffffdfff
[   10.188008] R10: ffffffffa2670880 R11: ffffffffa2670880 R12: ffff9daa83100000
[   10.188010] R13: ffffffffa1e1c4fc R14: ffff9daa822d8200 R15: 0000000000000000
[   10.188017] FS:  00007fe0e810d740(0000) GS:ffff9dabb7c00000(0000) knlGS:0000000000000000
[   10.188021] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   10.188024] CR2: 00007f1a0e26ece0 CR3: 000000010318d003 CR4: 0000000000170ef0
[   10.188027] Call Trace:
[   10.188031]  <TASK>
[   10.188035]  ipv6_frags_init_net+0xbd/0x150
[   10.188046]  ops_init+0x37/0x120
[   10.188051]  setup_net+0x12a/0x290
[   10.188057]  copy_net_ns+0xd8/0x180
[   10.188062]  create_new_namespaces+0x123/0x300
[   10.188071]  unshare_nsproxy_namespaces+0x60/0xa0
[   10.188078]  ksys_unshare+0x181/0x360
[   10.188087]  __x64_sys_unshare+0x12/0x20
[   10.188094]  do_syscall_64+0x38/0x80
[   10.188100]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   10.188108] RIP: 0033:0x7fe0e82f23cb
[   10.188113] Code: 73 01 c3 48 8b 0d 65 5a 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 10 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 35 5a 0c 00 f7 d8 64 89 01 48
[   10.188117] RSP: 002b:00007ffe0513ec08 EFLAGS: 00000217 ORIG_RAX: 0000000000000110
[   10.188122] RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fe0e82f23cb
[   10.188125] RDX: 0000000000000000 RSI: 000056387c863113 RDI: 0000000040000000
[   10.188128] RBP: 000056387c862c3a R08: 0000000000000000 R09: 0000000000000073
[   10.188131] R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000000000
[   10.188133] R13: 00007fe0e810d6b8 R14: 00007ffe05140e10 R15: 000056387c864fe5
[   10.188138]  </TASK>
[   10.188140] ---[ end trace 0000000000000000 ]---